Home » Biology » AP Biology » AP Biology Practice Exam: Section I, Part A, Multiple Choice Questions 1-31

Dr. Carleen Eaton

Dr. Carleen Eaton

AP Biology Practice Exam: Section I, Part A, Multiple Choice Questions 1-31

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Table of Contents

Section 1: Chemistry of Life
Elements, Compounds, and Chemical Bonds

56m 18s

Intro
0:00
Elements
0:09
Elements
0:48
Matter
0:55
Naturally Occurring Elements
1:12
Atomic Number and Atomic Mass
2:39
Compounds
3:06
Molecule
3:07
Compounds
3:14
Examples
3:20
Atoms
4:53
Atoms
4:56
Protons, Neutrons, and Electrons
5:29
Isotopes
10:42
Energy Levels of Electrons
13:01
Electron Shells
13:13
Valence Shell
13:22
Example: Electron Shells and Potential Energy
13:28
Covalent Bonds
19:52
Covalent Bonds
19:54
Examples
20:03
Polar and Nonpolar Covalent Bonds
23:54
Polar Bond
24:07
Nonpolar Bonds
24:17
Examples
24:25
Ionic Bonds
29:04
Ionic Bond, Cations, Anions
29:19
Example: NaCl
29:30
Hydrogen Bond
33:18
Hydrogen Bond
33:20
Chemical Reactions
35:36
Example: Reactants, Products and Chemical Reactions
35:45
Molecular Mass and Molar Concentration
38:45
Avogadro's Number and Mol
39:12
Examples: Molecular Mass and Molarity
42:10
Example 1: Proton, Neutrons and Electrons
47:05
Example 2: Reactants and Products
49:35
Example 3: Bonding
52:39
Example 4: Mass
53:59
Properties of Water

50m 23s

Intro
0:00
Molecular Structure of Water
0:21
Molecular Structure of Water
0:27
Properties of Water
4:30
Cohesive
4:55
Transpiration
5:29
Adhesion
6:20
Surface Tension
7:17
Properties of Water, cont.
9:14
Specific Heat
9:25
High Heat Capacity
13:24
High Heat of Evaporation
16:42
Water as a Solvent
21:13
Solution
21:28
Solvent
21:48
Example: Water as a Solvent
22:22
Acids and Bases
25:40
Example
25:41
pH
36:30
pH Scale: Acidic, Neutral, and Basic
36:35
Example 1: Molecular Structure and Properties of Water
41:18
Example 2: Special Properties of Water
42:53
Example 3: pH Scale
44:46
Example 4: Acids and Bases
46:19
Organic Compounds

53m 54s

Intro
0:00
Organic Compounds
0:09
Organic Compounds
0:11
Inorganic Compounds
0:15
Examples: Organic Compounds
1:15
Isomers
5:52
Isomers
5:55
Structural Isomers
6:23
Geometric Isomers
8:14
Enantiomers
9:55
Functional Groups
12:46
Examples: Functional Groups
12:59
Amino Group
13:51
Carboxyl Group
14:38
Hydroxyl Group
15:22
Methyl Group
16:14
Carbonyl Group
16:30
Phosphate Group
17:51
Carbohydrates
18:26
Carbohydrates
19:07
Example: Monosaccharides
21:12
Carbohydrates, cont.
24:11
Disaccharides, Polysaccharides and Examples
24:21
Lipids
35:52
Examples of Lipids
36:04
Saturated and Unsaturated
38:57
Phospholipids
43:26
Phospholipids
43:29
Example
43:34
Steroids
46:24
Cholesterol
46:28
Example 1: Isomers
48:11
Example 2: Functional Groups
50:45
Example 3: Galactose, Ketose, and Aldehyde Sugar
52:24
Example 4: Class of Molecules
53:06
Nucleic Acids and Proteins

37m 23s

Intro
0:00
Nucleic Acids
0:09
Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA)
0:29
Nucleic Acids, cont.
2:56
Purines
3:10
Pyrimidines
3:32
Double Helix
4:59
Double Helix and Example
5:01
Proteins
12:33
Amino Acids and Polypeptides
12:39
Examples: Amino Acid
13:25
Polypeptide Formation
18:09
Peptide Bonds
18:14
Primary Structure
18:35
Protein Structure
23:19
Secondary Structure
23:22
Alpha Helices and Beta Pleated Sheets
23:34
Protein Structure
25:43
Tertiary Structure
25:44
5 Types of Interaction
26:56
Example 1: Complementary DNA Strand
31:45
Example 2: Differences Between DNA and RNA
33:19
Example 3: Amino Acids
34:32
Example 4: Tertiary Structure of Protein
35:46
Section 2: Cell Structure and Function
Cell Types (Prokaryotic and Eukaryotic)

45m 50s

Intro
0:00
Cell Theory and Cell Types
0:12
Cell Theory
0:13
Prokaryotic and Eukaryotic Cells
0:36
Endosymbiotic Theory
1:13
Study of Cells
4:07
Tools and Techniques
4:08
Light Microscopes
5:08
Light vs. Electron Microscopes: Magnification
5:18
Light vs. Electron Microscopes: Resolution
6:26
Light vs. Electron Microscopes: Specimens
7:53
Electron Microscopes: Transmission and Scanning
8:28
Cell Fractionation
10:01
Cell Fractionation Step 1: Homogenization
10:33
Cell Fractionation Step 2: Spin
11:24
Cell Fractionation Step 3: Differential Centrifugation
11:53
Comparison of Prokaryotic and Eukaryotic Cells
14:12
Prokaryotic vs. Eukaryotic Cells: Domains
14:43
Prokaryotic vs. Eukaryotic Cells: Plasma Membrane
15:40
Prokaryotic vs. Eukaryotic Cells: Cell Walls
16:15
Prokaryotic vs. Eukaryotic Cells: Genetic Materials
16:38
Prokaryotic vs. Eukaryotic Cells: Structures
17:28
Prokaryotic vs. Eukaryotic Cells: Unicellular and Multicellular
18:19
Prokaryotic vs. Eukaryotic Cells: Size
18:31
Plasmids
18:52
Prokaryotic vs. Eukaryotic Cells
19:22
Nucleus
19:24
Organelles
19:48
Cytoskeleton
20:02
Cell Wall
20:35
Ribosomes
20:57
Size
21:37
Comparison of Plant and Animal Cells
22:15
Plasma Membrane
22:55
Plant Cells Only: Cell Walls
23:12
Plant Cells Only: Central Vacuole
25:08
Animal Cells Only: Centrioles
26:40
Animal Cells Only: Lysosomes
27:43
Plant vs. Animal Cells
29:16
Overview of Plant and Animal Cells
29:17
Evidence for the Endosymbiotic Theory
30:52
Characteristics of Mitochondria and Chloroplasts
30:54
Example 1: Prokaryotic vs. Eukaryotic Cells
35:44
Example 2: Endosymbiotic Theory and Evidence
38:38
Example 3: Plant and Animal Cells
41:49
Example 4: Cell Fractionation
43:44
Subcellular Structure

59m 38s

Intro
0:00
Prokaryotic Cells
0:09
Shapes of Prokaryotic Cells
0:22
Cell Wall
1:19
Capsule
3:23
Pili/Fimbria
3:54
Flagella
4:35
Nucleoid
6:16
Plasmid
6:37
Ribosomes
7:09
Eukaryotic Cells (Animal Cell Structure)
8:01
Plasma Membrane
8:13
Microvilli
8:48
Nucleus
9:47
Nucleolus
11:06
Ribosomes: Free and Bound
12:26
Rough Endoplasmic Reticulum (RER)
13:43
Eukaryotic Cells (Animal Cell Structure), cont.
14:51
Endoplasmic Reticulum: Smooth and Rough
15:08
Golgi Apparatus
17:55
Vacuole
20:43
Lysosome
22:01
Mitochondria
25:40
Peroxisomes
28:18
Cytoskeleton
30:41
Cytoplasm and Cytosol
30:53
Microtubules: Centrioles, Spindel Fibers, Clagell, Cillia
32:06
Microfilaments
36:39
Intermediate Filaments and Kerotin
38:52
Eukaryotic Cells (Plant Cell Structure)
40:08
Plasma Membrane, Primary Cell Wall, and Secondary Cell Wall
40:30
Middle Lamella
43:21
Central Cauole
44:12
Plastids: Leucoplasts, Chromoplasts, Chrloroplasts
45:35
Chloroplasts
47:06
Example 1: Structures and Functions
48:46
Example 2: Cell Walls
51:19
Example 3: Cytoskeleton
52:53
Example 4: Antibiotics and the Endosymbiosis Theory
56:55
Cell Membranes and Transport

53m 10s

Intro
0:00
Cell Membrane Structure
0:09
Phospholipids Bilayer
0:11
Chemical Structure: Amphipathic and Fatty Acids
0:25
Cell Membrane Proteins
2:44
Fluid Mosaic Model
2:45
Peripheral Proteins and Integral Proteins
3:19
Transmembrane Proteins
4:34
Cholesterol
4:48
Functions of Membrane Proteins
6:39
Transport Across Cell Membranes
9:52
Transport Across Cell Membranes
9:53
Methods of Passive Transport
12:07
Passive and Active Transport
12:08
Simple Diffusion
12:45
Facilitated Diffusion
15:20
Osmosis
17:17
Definition and Example of Osmosis
17:18
Hypertonic, Hypotonic, and Isotonic
21:47
Active Transport
27:57
Active Transport
28:17
Sodium and Potassium Pump
29:45
Cotransport
34:38
2 Types of Active Transport
37:09
Endocytosis and Exocytosis
37:38
Endocytosis and Exocytosis
37:51
Types of Endocytosis: Pinocytosis
40:39
Types of Endocytosis: Phagocytosis
41:02
Receptor Mediated Endocytosis
41:27
Receptor Mediated Endocytosis
41:28
Example 1: Cell Membrane and Permeable Substances
43:59
Example 2: Osmosis
45:20
Example 3: Active Transport, Cotransport, Simple and Facilitated Diffusion
47:36
Example 4: Match Terms with Definition
50:55
Cellular Communication

57m 9s

Intro
0:00
Extracellular Matrix
0:28
The Extracellular Matrix (ECM)
0:29
ECM in Animal Cells
0:55
Fibronectin and Integrins
1:34
Intercellular Communication in Plants
2:48
Intercellular Communication in Plants: Plasmodesmata
2:50
Cell to Cell Communication in Animal Cells
3:39
Cell Junctions
3:42
Desmosomes
3:54
Tight Junctions
5:07
Gap Junctions
7:00
Cell Signaling
8:17
Cell Signaling: Ligand and Signal Transduction Pathway
8:18
Direct Contact
8:48
Over Distances Contact and Hormones
10:09
Stages of Cell Signaling
11:53
Reception Phase
11:54
Transduction Phase
13:49
Response Phase
14:45
Cell Membrane Receptors
15:37
G-Protein Coupled Receptor
15:38
Cell Membrane Receptor, Cont.
21:37
Receptor Tyrosine Kinases (RTKs)
21:38
Autophosphorylation, Monomer, and Dimer
22:57
Cell Membrane Receptor, Cont.
27:01
Ligand-Gated Ion Channels
27:02
Intracellular Receptors
29:43
Intracellular Receptor and Receptor -Ligand Complex
29:44
Signal Transduction
32:57
Signal Transduction Pathways
32:58
Adenylyl Cyclase and cAMP
35:53
Second Messengers
39:18
cGMP, Inositol Trisphosphate, and Diacylglycerol
39:20
Cell Response
45:15
Cell Response
45:16
Apoptosis
46:57
Example 1: Tight Junction and Gap Junction
48:29
Example 2: Three Phases of Cell Signaling
51:48
Example 3: Ligands and Binding of Hormone
54:03
Example 4: Signal Transduction
56:06
Section 3: Cell Division
The Cell Cycle

37m 49s

Intro
0:00
Functions of Cell Division
0:09
Overview of Cell Division: Reproduction, Growth, and Repair
0:11
Important Term: Daughter Cells
2:25
Chromosome Structure
3:36
Chromosome Structure: Sister Chromatids and Centromere
3:37
Chromosome Structure: Chromatin
4:31
Chromosome with One Chromatid or Two Chromatids
5:25
Chromosome Structure: Long and Short Arm
6:49
Mitosis and Meiosis
7:00
Mitosis
7:41
Meiosis
8:40
The Cell Cycle
10:43
Mitotic Phase and Interphase
10:44
Cytokinesis
15:51
Cytokinesis in Animal Cell: Cleavage Furrow
15:52
Cytokinesis in Plant Cell: Cell Plate
17:28
Control of the Cell Cycle
18:28
Cell Cycle Control System and Checkpoints
18:29
Cyclins and Cyclin Dependent Kinases
21:18
Cyclins and Cyclin Dependent Kinases (CDKSs)
21:20
MPF
23:17
Internal Factor Regulating Cell Cycle
24:00
External Factor Regulating Cell Cycle
24:53
Contact Inhibition and Anchorage Dependent
25:53
Cancer and the Cell Cycle
27:42
Cancer Cells
27:46
Example1: Parts of the Chromosome
30:15
Example 2: Cell Cycle
31:50
Example 3: Control of the Cell Cycle
33:32
Example 4: Cancer and the Cell
35:01
Mitosis

35m 1s

Intro
0:00
Review of the Cell Cycle
0:09
Interphase: G1 Phase
0:34
Interphase: S Phase
0:56
Interphase: G2 Phase
1:31
M Phase: Mitosis and Cytokinesis
1:47
Overview of Mitosis
3:08
What is Mitosis?
3:10
Overview of Mitosis
3:17
Diploid and Haploid
5:37
Homologous Chromosomes
6:04
The Spindle Apparatus
11:57
The Spindle Apparatus
12:00
Centrosomes and Centrioles
12:40
Microtubule Organizing Center
13:03
Spindle Fiber of Spindle Microtubules
13:23
Kinetochores
14:06
Asters
15:45
Prophase
16:47
First Phase of Mitosis: Prophase
16:54
Metaphase
20:05
Second Phase of Mitosis: Metaphase
20:10
Anaphase
22:52
Third Phase of Mitosis: Anaphase
22:53
Telophase and Cytokinesis
24:34
Last Phase of Mitosis: Telophase and Cytokinesis
24:35
Summary of Mitosis
27:46
Summary of Mitosis
27:47
Example 1: Spindle Apparatus
28:50
Example 2: Last Phase of Mitosis
30:39
Example 3: Prophase
32:41
Example 4: Identify the Phase
33:52
Meiosis

1h 58s

Intro
0:00
Haploid and Diploid Cells
0:09
Diploid and Somatic Cells
0:29
Haploid and Gametes
1:20
Example: Human Cells and Chromosomes
1:41
Sex Chromosomes
6:00
Comparison of Mitosis and Meiosis
10:42
Mitosis Vs. Meiosis: Cell Division
10:59
Mitosis Vs. Meiosis: Daughter Cells
12:31
Meiosis: Pairing of Homologous Chromosomes
13:40
Mitosis and Meiosis
14:21
Process of Mitosis
14:27
Process of Meiosis
16:12
Synapsis and Crossing Over
19:14
Prophase I: Synapsis and Crossing Over
19:15
Chiasmata
22:33
Meiosis I
25:49
Prophase I: Crossing Over
25:50
Metaphase I: Homologs Line Up
26:00
Anaphase I: Homologs Separate
28:16
Telophase I and Cytokinesis
29:15
Independent Assortment
30:58
Meiosis II
32:17
Propphase II
33:50
Metaphase II
34:06
Anaphase II
34:50
Telophase II
36:09
Cytokinesis
37:00
Summary of Meiosis
38:15
Summary of Meiosis
38:16
Cell Division Mechanism in Plants
41:57
Example 1: Cell Division and Meiosis
46:15
Example 2: Phases of Meiosis
50:22
Example 3: Label the Figure
54:29
Example 4: Four Differences Between Mitosis and Meiosis
56:37
Section 4: Cellular Energetics
Enzymes

51m 3s

Intro
0:00
Law of Thermodynamics
0:08
Thermodynamics
0:09
The First Law of Thermodynamics
0:37
The Second Law of Thermodynamics
1:24
Entropy
1:35
The Gibbs Free Energy Equation
3:07
The Gibbs Free Energy Equation
3:08
ATP
8:23
Adenosine Triphosphate (ATP)
8:24
Cellular Respiration
11:32
Catabolic Pathways
12:28
Anabolic Pathways
12:54
Enzymes
14:31
Enzymes
14:32
Enzymes and Exergonic Reaction
14:40
Enzymes and Endergonic Reaction
16:36
Enzyme Specificity
21:29
Substrate
21:41
Induced Fit
23:04
Factors Affecting Enzyme Activity
25:55
Substrate Concentration
26:07
pH
27:10
Temperature
29:14
Presence of Cofactors
29:57
Regulation of Enzyme Activity
31:12
Competitive Inhibitors
32:13
Noncompetitive Inhibitors
33:52
Feedback Inhibition
35:22
Allosteric Interactions
36:56
Allosteric Regulators
37:00
Example 1: Is the Inhibitor Competitive or Noncompetitive?
40:49
Example 2: Thermophiles
44:18
Example 3: Exergonic or Endergonic
46:09
Example 4: Energy Vs. Reaction Progress Graph
48:47
Glycolysis and Anaerobic Respiration

38m 1s

Intro
0:00
Cellular Respiration Overview
0:13
Cellular Respiration
0:14
Anaerobic Respiration vs. Aerobic Respiration
3:50
Glycolysis Overview
4:48
Overview of Glycolysis
4:50
Glycolysis Involves a Redox Reaction
7:02
Redox Reaction
7:04
Glycolysis
15:04
Important Facts About Glycolysis
15:07
Energy Invested Phase
16:12
Splitting of Fructose 1,6-Phosphate and Energy Payoff Phase
17:50
Substrate Level Phophorylation
22:12
Aerobic Versus Anaerobic Respiration
23:57
Aerobic Versus Anaerobic Respiration
23:58
Cellular Respiration Overview
27:15
When Cellular Respiration is Anaerobic
27:17
Glycolysis
28:26
Alcohol Fermentation
28:45
Lactic Acid Fermentation
29:58
Example 1: Glycolysis
31:04
Example 2: Glycolysis, Fermentation and Anaerobic Respiration
33:44
Example 3: Aerobic Respiration Vs. Anaerobic Respiration
35:25
Example 4: Exergonic Reaction and Endergonic Reaction
36:42
Aerobic Respiration

51m 6s

Intro
0:00
Aerobic Vs. Anaerobic Respiration
0:06
Aerobic and Anaerobic Comparison
0:07
Review of Glycolysis
1:48
Overview of Glycolysis
2:06
Glycolysis: Energy Investment Phase
2:25
Glycolysis: Energy Payoff Phase
2:58
Conversion of Pyruvate to Acetyl CoA
4:55
Conversion of Pyruvate to Acetyl CoA
4:56
Energy Formation
8:06
Mitochondrial Structure
8:58
Endosymbiosis Theory
9:23
Matrix
10:00
Outer Membrane, Inner Membrane, and Intermembrane Space
10:43
Cristae
11:47
The Citric Acid Cycle
12:11
The Citric Acid Cycle (Also Called Krebs Cycle)
12:12
Substrate Level Phosphorylation
18:47
Summary of ATP, NADH, and FADH2 Production
23:13
Process: Glycolysis
23:28
Process: Acetyl CoA Production
23:36
Process: Citric Acid Cycle
23:52
The Electron Transport Chain
24:24
Oxidative Phosphorylation
24:28
The Electron Transport Chain and ATP Synthase
25:20
Carrier Molecules: Cytochromes
27:18
Carrier Molecules: Flavin Mononucleotide (FMN)
28:05
Chemiosmosis
32:46
The Process of Chemiosmosis
32:47
Summary of ATP Produced by Aerobic Respiration
38:24
ATP Produced by Aerobic Respiration
38:27
Example 1: Aerobic Respiration
43:38
Example 2: Label the Location for Each Process and Structure
45:08
Example 3: The Electron Transport Chain
47:06
Example 4: Mitochondrial Inner Membrane
48:38
Photosynthesis

1h 2m 52s

Intro
0:00
Photosynthesis
0:09
Introduction to Photosynthesis
0:10
Autotrophs and Heterotrophs
0:25
Overview of Photosynthesis Reaction
1:05
Leaf Anatomy and Chloroplast Structure
2:54
Chloroplast
2:55
Cuticle
3:16
Upper Epidermis
3:27
Mesophyll
3:40
Stomates
4:00
Guard Cells
4:45
Transpiration
5:01
Vascular Bundle
5:20
Stroma and Double Membrane
6:20
Grana
7:17
Thylakoids
7:30
Dark Reaction and Light Reaction
7:46
Light Reactions
8:43
Light Reactions
8:47
Pigments: Chlorophyll a, Chlorophyll b, and Carotenoids
9:19
Wave and Particle
12:10
Photon
12:34
Photosystems
13:24
Photosystems
13:28
Reaction-Center Complex and Light Harvesting Complexes
14:01
Noncyclic Photophosphorylation
17:46
Noncyclic Photophosphorylation Overview
17:47
What is Photophosphorylation?
18:25
Noncyclic Photophosphorylation Process
19:07
Photolysis and The Rest of Noncyclic Photophosphorylation
21:33
Cyclic Photophosphorylation
31:45
Cyclic Photophosphorylation
31:46
Light Independent Reactions
34:34
The Calvin Cycle
34:35
C3 Plants and Photorespiration
40:31
C3 Plants and Photorespiration
40:32
C4 Plants
45:32
C4 Plants: Structures and Functions
45:33
CAM Plants
50:25
CAM Plants: Structures and Functions
50:35
Example 1: Calvin Cycle
54:34
Example 2: C4 Plant
55:48
Example 3: Photosynthesis and Photorespiration
58:35
Example 4: CAM Plants
1:00:41
Section 5: Molecular Genetics
DNA Synthesis

38m 45s

Intro
0:00
Review of DNA Structure
0:09
DNA Molecules
0:10
Nitrogenous Base: Pyrimidines and Purines
1:25
DNA Double Helix
3:03
Complementary Strands of DNA
3:12
5' to 3' & Antiparallel
4:55
Overview of DNA Replication
7:10
DNA Replication & Semiconservative
7:11
DNA Replication
10:26
Origin of Replication
10:28
Helicase
11:10
Single-Strand Binding Protein
12:05
Topoisomerases
13:14
DNA Polymerase
14:26
Primase
15:55
Leading and Lagging Strands
16:51
Leading Strand and Lagging Strand
16:52
Okazaki Fragments
18:10
DNA Polymerase I
20:11
Ligase
21:12
Proofreading and Mismatch Repair
22:18
Proofreading
22:19
Mismatch
23:33
Telomeres
24:58
Telomeres
24:59
Example 1: Function of Enzymes During DNA Synthesis
28:09
Example 2: Accuracy of the DNA Sequence
31:42
Example 3: Leading Strand and Lagging Strand
32:38
Example 4: Telomeres
35:40
Transcription and Translation

1h 17m 1s

Intro
0:00
Transcription and Translation Overview
0:07
From DNA to RNA to Protein
0:09
Structure and Types of RNA
3:14
Structure and Types of RNA
3:33
mRNA
6:19
rRNA
7:02
tRNA
7:28
Transcription
7:54
Initiation Phase
8:11
Elongation Phase
12:12
Termination Phase
14:51
RNA Processing
16:11
Types of RNA Processing
16:12
Exons and Introns
16:35
Splicing & Spliceosomes
18:27
Addition of a 5' Cap and a Poly A tail
20:41
Alternative Splicing
21:43
Translation
23:41
Nucleotide Triplets or Codons
23:42
Start Codon
25:24
Stop Codons
25:38
Coding of Amino Acids and Wobble Position
25:57
Translation Cont.
28:29
Transfer RNA (tRNA): Structures and Functions
28:30
Ribosomes
35:15
Peptidyl, Aminoacyl, and Exit Site
35:23
Steps of Translation
36:58
Initiation Phase
37:12
Elongation Phase
43:12
Termination Phase
45:28
Mutations
49:43
Types of Mutations
49:44
Substitutions: Silent
51:11
Substitutions: Missense
55:27
Substitutions: Nonsense
59:37
Insertions and Deletions
1:01:10
Example 1: Three Types of Processing that are Performed on pre-mRNA
1:06:53
Example 2: The Process of Translation
1:09:10
Example 3: Transcription
1:12:04
Example 4: Three Types of Substitution Mutations
1:14:09
Viral Structure and Genetics

43m 12s

Intro
0:00
Structure of Viruses
0:09
Structure of Viruses: Capsid and Envelope
0:10
Bacteriophage
1:48
Other Viruses
2:28
Overview of Viral Reproduction
3:15
Host Range
3:48
Step 1: Bind to Host Cell
4:39
Step 2: Viral Nuclei Acids Enter the Cell
5:15
Step 3: Viral Nucleic Acids & Proteins are Synthesized
5:54
Step 4: Virus Assembles
6:34
Step 5: Virus Exits the Cell
6:55
The Lytic Cycle
7:37
Steps in the Lytic Cycle
7:38
The Lysogenic Cycle
11:27
Temperate Phage
11:34
Steps in the Lysogenic Cycle
12:09
RNA Viruses
16:57
Types of RNA Viruses
17:15
Positive Sense
18:16
Negative Sense
18:48
Reproductive Cycle of RNA Viruses
19:32
Retroviruses
25:48
Complementary DNA (cDNA) & Reverse Transcriptase
25:49
Life Cycle of a Retrovirus
28:22
Prions
32:42
Prions: Definition and Examples
32:45
Viroids
34:46
Example 1: The Lytic Cycle
35:37
Example 2: Retrovirus
38:03
Example 3: Positive Sense RNA vs. Negative Sense RNA
39:10
Example 4: The Lysogenic Cycle
40:42
Bacterial Genetics and Gene Regulation

49m 45s

Intro
0:00
Bacterial Genomes
0:09
Structure of Bacterial Genomes
0:16
Transformation
1:22
Transformation
1:23
Vector
2:49
Transduction
3:32
Process of Transduction
3:38
Conjugation
8:06
Conjugation & F factor
8:07
Operons
14:02
Definition and Example of Operon
14:52
Structural Genes
16:23
Promoter Region
17:04
Regulatory Protein & Operators
17:53
The lac Operon
20:09
The lac Operon: Inducible System
20:10
The trp Operon
28:02
The trp Operon: Repressible System
28:03
Corepressor
31:37
Anabolic & Catabolic
33:12
Positive Regulation of the lac Operon
34:39
Positive Regulation of the lac Operon
34:40
Example 1: The Process of Transformation
39:07
Example 2: Operon & Terms
43:29
Example 3: Inducible lac Operon and Repressible trp Operon
45:15
Example 4: lac Operon
47:10
Eukaryotic Gene Regulation and Mobile Genetic Elements

54m 26s

Intro
0:00
Mechanism of Gene Regulation
0:11
Differential Gene Expression
0:13
Levels of Regulation
2:24
Chromatin Structure and Modification
4:35
Chromatin Structure
4:36
Levels of Packing
5:50
Euchromatin and Heterochromatin
8:58
Modification of Chromatin Structure
9:58
Epigenetic
12:49
Regulation of Transcription
14:20
Promoter Region, Exon, and Intron
14:26
Enhancers: Control Element
15:31
Enhancer & DNA-Bending Protein
17:25
Coordinate Control
21:23
Silencers
23:01
Post-Transcriptional Regulation
24:05
Post-Transcriptional Regulation
24:07
Alternative Splicing
27:19
Differences in mRNA Stability
28:02
Non-Coding RNA Molecules: micro RNA & siRNA
30:01
Regulation of Translation and Post-Translational Modifications
32:31
Regulation of Translation and Post-Translational Modifications
32:55
Ubiquitin
35:21
Proteosomes
36:04
Transposons
37:50
Mobile Genetic Elements
37:56
Barbara McClintock
38:37
Transposons & Retrotransposons
40:38
Insertion Sequences
43:14
Complex Transposons
43:58
Example 1: Four Mechanisms that Decrease Production of Protein
45:13
Example 2: Enhancers and Gene Expression
49:09
Example 3: Primary Transcript
50:41
Example 4: Retroviruses and Retrotransposons
52:11
Biotechnology

49m 26s

Intro
0:00
Definition of Biotechnology
0:08
Biotechnology
0:09
Genetic Engineering
1:05
Example: Golden Corn
1:57
Recombinant DNA
2:41
Recombinant DNA
2:42
Transformation
3:24
Transduction
4:24
Restriction Enzymes, Restriction Sites, & DNA Ligase
5:32
Gene Cloning
13:48
Plasmids
14:20
Gene Cloning: Step 1
17:35
Gene Cloning: Step 2
17:57
Gene Cloning: Step 3
18:53
Gene Cloning: Step 4
19:46
Gel Electrophoresis
27:25
What is Gel Electrophoresis?
27:26
Gel Electrophoresis: Step 1
28:13
Gel Electrophoresis: Step 2
28:24
Gel Electrophoresis: Step 3 & 4
28:39
Gel Electrophoresis: Step 5
29:55
Southern Blotting
31:25
Polymerase Chain Reaction (PCR)
32:11
Polymerase Chain Reaction (PCR)
32:12
Denaturing Phase
35:40
Annealing Phase
36:07
Elongation/ Extension Phase
37:06
DNA Sequencing and the Human Genome Project
39:19
DNA Sequencing and the Human Genome Project
39:20
Example 1: Gene Cloning
40:40
Example 2: Recombinant DNA
43:04
Example 3: Match Terms With Descriptions
45:43
Example 4: Polymerase Chain Reaction
47:36
Section 6: Heredity
Mendelian Genetics

1h 32m 8s

Intro
0:00
Background
0:40
Gregory Mendel & Mendel's Law
0:41
Blending Hypothesis
1:04
Particulate Inheritance
2:08
Terminology
2:55
Gene
3:05
Locus
3:57
Allele
4:37
Dominant Allele
5:48
Recessive Allele
7:38
Genotype
9:22
Phenotype
10:01
Homozygous
10:44
Heterozygous
11:39
Penetrance
11:57
Expressivity
14:15
Mendel's Experiments
15:31
Mendel's Experiments: Pea Plants
15:32
The Law of Segregation
21:16
Mendel's Conclusions
21:17
The Law of Segregation
22:57
Punnett Squares
28:27
Using Punnet Squares
28:30
The Law of Independent Assortment
32:35
Monohybrid
32:38
Dihybrid
33:29
The Law of Independent Assortment
34:00
The Law of Independent Assortment, cont.
38:13
The Law of Independent Assortment: Punnet Squares
38:29
Meiosis and Mendel's Laws
43:38
Meiosis and Mendel's Laws
43:39
Test Crosses
49:07
Test Crosses Example
49:08
Probability: Multiplication Rule and the Addition Rule
53:39
Probability Overview
53:40
Independent Events & Multiplication Rule
55:40
Mutually Exclusive Events & Addition Rule
1:00:25
Incomplete Dominance, Codominance and Multiple Alleles
1:02:55
Incomplete Dominance
1:02:56
Incomplete Dominance, Codominance and Multiple Alleles
1:07:06
Codominance and Multiple Alleles
1:07:08
Polygenic Inheritance and Pleoitropy
1:10:19
Polygenic Inheritance and Pleoitropy
1:10:26
Epistasis
1:12:51
Example of Epistasis
1:12:52
Example 1: Genetic of Eye Color and Height
1:17:39
Example 2: Blood Type
1:21:57
Example 3: Pea Plants
1:25:09
Example 4: Coat Color
1:28:34
Linked Genes and Non-Mendelian Modes of Inheritance

39m 38s

Intro
0:00
Review of the Law of Independent Assortment
0:14
Review of the Law of Independent Assortment
0:24
Linked Genes
6:06
Linked Genes
6:07
Bateson & Pannett: Pea Plants
8:00
Crossing Over and Recombination
15:17
Crossing Over and Recombination
15:18
Extranuclear Genes
20:50
Extranuclear Genes
20:51
Cytoplasmic Genes
21:31
Genomic Imprinting
23:45
Genomic Imprinting
23:58
Methylation
24:43
Example 1: Recombination Frequencies & Linkage Map
27:07
Example 2: Linked Genes
28:39
Example 3: Match Terms to Correct Descriptions
36:46
Example 4: Leber's Optic Neuropathy
38:40
Sex-Linked Traits and Pedigree Analysis

43m 39s

Intro
0:00
Sex-Linked Traits
0:09
Human Chromosomes, XY, and XX
0:10
Thomas Morgan's Drosophila
1:44
X-Inactivation and Barr Bodies
14:48
X-Inactivation Overview
14:49
Calico Cats Example
17:04
Pedigrees
19:24
Definition and Example of Pedigree
19:25
Autosomal Dominant Inheritance
20:51
Example: Huntington's Disease
20:52
Autosomal Recessive Inheritance
23:04
Example: Cystic Fibrosis, Tay-Sachs Disease, and Phenylketonuria
23:05
X-Linked Recessive Inheritance
27:06
Example: Hemophilia, Duchene Muscular Dystrohpy, and Color Blindess
27:07
Example 1: Colorblind
29:48
Example 2: Pedigree
37:07
Example 3: Inheritance Pattern
39:54
Example 4: X-inactivation
41:17
Section 7: Evolution
Natural Selection

1h 3m 28s

Intro
0:00
Background
0:09
Work of Other Scientists
0:15
Aristotle
0:43
Carl Linnaeus
1:32
George Cuvier
2:47
James Hutton
4:10
Thomas Malthus
5:05
Jean-Baptiste Lamark
5:45
Darwin's Theory of Natural Selection
7:50
Evolution
8:00
Natural Selection
8:43
Charles Darwin & The Galapagos Islands
10:20
Genetic Variation
20:37
Mutations
20:38
Independent Assortment
21:04
Crossing Over
24:40
Random Fertilization
25:26
Natural Selection and the Peppered Moth
26:37
Natural Selection and the Peppered Moth
26:38
Types of Natural Selection
29:52
Directional Selection
29:55
Stabilizing Selection
32:43
Disruptive Selection
34:21
Sexual Selection
36:18
Sexual Dimorphism
37:30
Intersexual Selection
37:57
Intrasexual Selection
39:20
Evidence for Evolution
40:55
Paleontology: Fossil Record
41:30
Biogeography
45:35
Continental Drift
46:06
Pangaea
46:28
Marsupials
47:11
Homologous and Analogous Structure
50:10
Homologous Structure
50:12
Analogous Structure
53:21
Example 1: Genetic Variation & Natural Selection
56:15
Example 2: Types of Natural Selection
58:07
Example 3: Mechanisms By Which Genetic Variation is Maintained Within a Population
1:00:12
Example 4: Difference Between Homologous and Analogous Structures
1:01:28
Population Genetic and Evolution

53m 22s

Intro
0:00
Review of Natural Selection
0:12
Review of Natural Selection
0:13
Genetic Drift and Gene Flow
4:40
Definition of Genetic Drift
4:41
Example of Genetic Drift: Cholera Epidemic
5:15
Genetic Drift: Founder Effect
7:28
Genetic Drift: Bottleneck Effect
10:27
Gene Flow
13:00
Quantifying Genetic Variation
14:32
Average Heterozygosity
15:08
Nucleotide Variation
17:05
Maintaining Genetic Variation
18:12
Heterozygote Advantage
19:45
Example of Heterozygote Advantage: Sickle Cell Anemia
20:21
Diploidy
23:44
Geographic Variation
26:54
Frequency Dependent Selection and Outbreeding
28:15
Neutral Traits
30:55
The Hardy-Weinberg Equilibrium
31:11
The Hardy-Weinberg Equilibrium
31:49
The Hardy-Weinberg Conditions
32:42
The Hardy-Weinberg Equation
34:05
The Hardy-Weinberg Example
36:33
Example 1: Match Terms to Descriptions
42:28
Example 2: The Hardy-Weinberg Equilibrium
44:31
Example 3: The Hardy-Weinberg Equilibrium
49:10
Example 4: Maintaining Genetic Variation
51:30
Speciation and Patterns of Evolution

51m 2s

Intro
0:00
Early Life on Earth
0:08
Early Earth
0:09
1920's Oparin & Haldane
0:58
Abiogenesis
2:15
1950's Miller & Urey
2:45
Ribozymes
5:34
3.5 Billion Years Ago
6:39
2.5 Billion Years Ago
7:14
1.5 Billion Years Ago
7:41
Endosymbiosis
8:00
540 Million Years Ago: Cambrian Explosion
9:57
Gradualism and Punctuated Equilibrium
11:46
Gradualism
11:47
Punctuated Equilibrium
12:45
Adaptive Radiation
15:08
Adaptive Radiation
15:09
Example of Adaptive Radiation: Galapogos Islands
17:11
Convergent Evolution, Divergent Evolution, and Coevolution
18:30
Convergent Evolution
18:39
Divergent Evolution
21:30
Coevolution
23:49
Speciation
26:27
Definition and Example of Species
26:29
Reproductive Isolation: Prezygotive
27:49
Reproductive Isolation: Post zygotic
29:28
Allopatric Speciation
30:21
Allopatric Speciation & Geographic Isolation
30:28
Genetic Drift
31:31
Sympatric Speciation
34:10
Sympatric Speciation
34:11
Polyploidy & Autopolyploidy
35:12
Habitat Isolation
39:17
Temporal Isolation
41:27
Selection Selection
41:40
Example 1: Pattern of Evolution
42:53
Example 2: Sympatric Speciation
45:16
Example 3: Patterns of Evolution
48:08
Example 4: Patterns of Evolution
49:27
Section 8: Diversity of Life
Classification

1h 51s

Intro
0:00
Systems of Classification
0:07
Taxonomy
0:08
Phylogeny
1:04
Phylogenetics Tree
1:44
Cladistics
3:37
Classification of Organisms
5:31
Example of Carl Linnaeus System
5:32
Domains
9:26
Kingdoms: Monera, Protista, Plantae, Fungi, Animalia
9:27
Monera
10:06
Phylogentics Tree: Eurkarya, Bacteria, Archaea
11:58
Domain Eukarya
12:50
Domain Bacteria
15:43
Domain Bacteria
15:46
Pathogens
16:41
Decomposers
18:00
Domain Archaea
19:43
Extremophiles Archaea: Thermophiles and Halophiles
19:44
Methanogens
20:58
Phototrophs, Autotrophs, Chemotrophs and Heterotrophs
24:40
Phototrophs and Chemotrophs
25:02
Autotrophs and Heterotrophs
26:54
Photoautotrophs
28:50
Photoheterotrophs
29:28
Chemoautotrophs
30:06
Chemoheterotrophs
31:37
Domain Eukarya
32:40
Domain Eukarya
32:43
Plant Kingdom
34:28
Protists
35:48
Fungi Kingdom
37:06
Animal Kingdom
38:35
Body Symmetry
39:25
Lack Symetry
39:40
Radial Symmetry: Sea Aneome
40:15
Bilateral Symmetry
41:55
Cephalization
43:29
Germ Layers
44:54
Diploblastic Animals
45:18
Triploblastic Animals
45:25
Ectoderm
45:36
Endoderm
46:07
Mesoderm
46:41
Coelomates
47:14
Coelom
47:15
Acoelomate
48:22
Pseudocoelomate
48:59
Coelomate
49:31
Protosomes
50:46
Deuterosomes
51:20
Example 1: Domains
53:01
Example 2: Match Terms with Descriptions
56:00
Example 3: Kingdom Monera and Domain Archaea
57:50
Example 4: System of Classification
59:37
Bacteria

36m 46s

Intro
0:00
Comparison of Domain Archaea and Domain Bacteria
0:08
Overview of Archaea and Bacteria
0:09
Archaea vs. Bacteria: Nucleus, Organelles, and Organization of Genetic Material
1:45
Archaea vs. Bacteria: Cell Walls
2:20
Archaea vs. Bacteria: Number of Types of RNA Pol
2:29
Archaea vs. Bacteria: Membrane Lipids
2:53
Archaea vs. Bacteria: Introns
3:33
Bacteria: Pathogen
4:03
Bacteria: Decomposers and Fix Nitrogen
5:18
Bacteria: Aerobic, Anaerobic, Strict Anaerobes & Facultative Anaerobes
6:02
Phototrophs, Autotrophs, Heterotrophs and Chemotrophs
7:14
Phototrophs and Chemotrophs
7:50
Autotrophs and Heterotrophs
8:53
Photoautotrophs and Photoheterotrophs
10:15
Chemoautotroph and Chemoheterotrophs
11:07
Structure of Bacteria
12:21
Shapes: Cocci, Bacilli, Vibrio, and Spirochetes
12:26
Structures: Plasma Membrane and Cell Wall
14:23
Structures: Nucleoid Region, Plasmid, and Capsule Basal Apparatus, and Filament
15:30
Structures: Flagella, Basal Apparatus, Hook, and Filament
16:36
Structures: Pili, Fimbrae and Ribosome
18:00
Peptidoglycan: Gram + and Gram -
18:50
Bacterial Genomes and Reproduction
21:14
Bacterial Genomes
21:21
Reproduction of Bacteria
22:13
Transformation
23:26
Vector
24:34
Competent
25:15
Conjugation
25:53
Conjugation: F+ and R Plasmids
25:55
Example 1: Species
29:41
Example 2: Bacteria and Exchange of Genetic Material
32:31
Example 3: Ways in Which Bacteria are Beneficial to Other Organisms
33:48
Example 4: Domain Bacteria vs. Domain Archaea
34:53
Protists

1h 18m 48s

Intro
0:00
Classification of Protists
0:08
Classification of Protists
0:09
'Plant-like' Protists
2:06
'Animal-like' Protists
3:19
'Fungus-like' Protists
3:57
Serial Endosymbiosis Theory
5:15
Endosymbiosis Theory
5:33
Photosynthetic Protists
7:33
Life Cycles with a Diploid Adult
13:35
Life Cycles with a Diploid Adult
13:56
Life Cycles with a Haploid Adult
15:31
Life Cycles with a Haploid Adult
15:32
Alternation of Generations
17:22
Alternation of Generations: Multicellular Haploid & Diploid Phase
17:23
Plant-Like Protists
19:58
Euglenids
20:43
Dino Flagellates
22:57
Diatoms
26:07
Plant-Like Protists
28:44
Golden Algae
28:45
Brown Algeas
30:05
Plant-Like Protists
33:38
Red Algae
33:39
Green Algae
35:36
Green Algae: Chlamydomonus
37:44
Animal-Like Protists
40:04
Animal-Like Protists Overview
40:05
Sporozoans (Apicomplexans)
40:32
Alveolates
41:41
Sporozoans (Apicomplexans): Plasmodium & Malaria
42:59
Animal-Like Protists
48:44
Kinetoplastids
48:50
Example of Kinetoplastids: Trypanosomes & African Sleeping Sickness
49:30
Ciliate
50:42
Conjugation
53:16
Conjugation
53:26
Animal-Like Protists
57:08
Parabasilids
57:31
Diplomonads
59:06
Rhizopods
1:00:13
Forams
1:02:25
Radiolarians
1:03:28
Fungus-Like Protists
1:04:25
Fungus-Like Protists Overview
1:04:26
Slime Molds
1:05:15
Cellular Slime Molds: Feeding Stage
1:09:21
Oomycetes
1:11:15
Example 1: Alternation of Generations and Sexual Life Cycles
1:13:05
Example 2: Match Protists to Their Descriptions
1:14:12
Example 3: Three Structures that Protists Use for Motility
1:16:22
Example 4: Paramecium
1:17:04
Fungi

35m 24s

Intro
0:00
Introduction to Fungi
0:09
Introduction to Fungi
0:10
Mycologist
0:34
Examples of Fungi
0:45
Hyphae, Mycelia, Chitin, and Coencytic Fungi
2:26
Ancestral Protists
5:00
Role of Fungi in the Environment
5:35
Fungi as Decomposers
5:36
Mycorrrhiza
6:19
Lichen
8:52
Life Cycle of Fungi
11:32
Asexual Reproduction
11:33
Sexual Reproduction & Dikaryotic Cell
13:16
Chytridiomycota
18:12
Phylum Chytridiomycota
18:17
Zoospores
18:50
Zygomycota
19:07
Coenocytic & Zygomycota Life Cycle
19:08
Basidiomycota
24:27
Basidiomycota Overview
24:28
Basidiomycota Life Cycle
26:11
Ascomycota
28:00
Ascomycota Overview
28:01
Ascomycota Reproduction
28:50
Example 1: Fungi Fill in the Blank
31:02
Example 2: Name Two Roles Played by Fungi in the Environment
32:09
Example 3: Difference Between Diploid Cell and Dikaryon Cell
33:42
Example 4: Phylum of Fungi, Flagellated Spore, Coencytic
34:36
Invertebrates

1h 3m 3s

Intro
0:00
Porifera (Sponges)
0:33
Chordata
0:56
Porifera (Sponges): Sessile, Layers, Aceolomates, and Filter Feeders
1:24
Amoebocytes Cell
4:47
Choanocytes Cell
5:56
Sexual Reproduction
6:28
Cnidaria
8:05
Cnidaria Overview
8:06
Polyp & Medusa: Gastrovasular Cavity
8:29
Cnidocytes
9:42
Anthozoa
10:40
Cubozoa
11:23
Hydrozoa
11:53
Scyphoza
13:25
Platyhelminthes (Flatworms)
13:58
Flatworms: Tribloblastic, Bilateral Symmetry, and Cephalization
13:59
GI System
15:33
Excretory System
16:07
Nervous System
17:00
Turbellarians
17:36
Trematodes
18:42
Monageneans
21:32
Cestoda
21:55
Rotifera (Rotifers)
23:45
Rotifers: Digestive Tract, Pseudocoelem, and Stuctures
23:46
Reproduction: Parthenogenesis
25:33
Nematoda (Roundworms)
26:44
Nematoda (Roundworms)
26:45
Parasites: Pinworms & Hookworms
27:26
Annelida
28:36
Annelida Overview
28:37
Open Circulatory
29:21
Closed Circulatory
30:18
Nervous System
31:19
Excretory System
31:43
Oligochaete
32:07
Leeches
33:22
Polychaetes
34:42
Mollusca
35:26
Mollusca Features
35:27
Major Part 1: Visceral Mass
36:21
Major Part 2: Head-foot Region
36:49
Major Part 3: Mantle
37:13
Radula
37:49
Circulatory, Reproductive, Excretory, and Nervous System
38:14
Major Classes of Molluscs
39:12
Gastropoda
39:17
Polyplacophora
40:15
Bivales
40:41
Cephalopods
41:42
Arthropoda
43:35
Arthropoda Overview
43:36
Segmented Bodies
44:14
Exoskeleton
44:52
Jointed Appendages
45:28
Hemolyph, Excretory & Respiratory System
45:41
Myriapoda & Centipedes
47:15
Cheliceriforms
48:20
Crustcea
49:31
Herapoda
50:03
Echinodermata
52:59
Echinodermata
53:00
Watrer Vascular System
54:20
Selected Characteristics of Invertebrates
57:11
Selected Characteristics of Invertebrates
57:12
Example 1: Phylum Description
58:43
Example 2: Complex Animals
59:50
Example 3: Match Organisms to the Correct Phylum
1:01:03
Example 4: Phylum Arthropoda
1:02:01
Vertebrates

1h 7s

Intro
0:00
Phylum Chordata
0:06
Chordates Overview
0:07
Notochord and Dorsal Hollow Nerve Chord
1:24
Pharyngeal Clefts, Arches, and Post-anal Tail
3:41
Invertebrate Chordates
6:48
Lancelets
7:13
Tunicates
8:02
Hagfishes: Craniates
8:55
Vertebrate Chordates
10:41
Veterbrates Overview
10:42
Lampreys
11:00
Gnathostomes
12:20
Six Major Classes of Vertebrates
12:53
chondrichthyes
14:23
Chondrichthyes Overview
14:24
Ectothermic and Endothermic
14:42
Sharks: Lateral Line System, Neuromastsn, and Gills
15:27
Oviparous and Viviparous
17:23
Osteichthyes (Bony Fishes)
18:12
Osteichythes (Bony Fishes) Overview
18:13
Operculum
19:05
Swim Bladder
19:53
Ray-Finned Fishes
20:34
Lobe-Finned Fishes
20:58
Tetrapods
22:36
Tetrapods: Definition and Examples
22:37
Amphibians
23:53
Amphibians Overview
23:54
Order Urodela
25:51
Order Apoda
27:03
Order Anura
27:55
Reptiles
30:19
Reptiles Overview
30:20
Amniotes
30:37
Examples of Reptiles
32:46
Reptiles: Ectotherms, Gas Exchange, and Heart
33:40
Orders of Reptiles
34:17
Sphenodontia, Squamata, Testudines, and Crocodilia
34:21
Birds
36:09
Birds and Dinosaurs
36:18
Theropods
38:00
Birds: High Metabolism, Respiratory System, Lungs, and Heart
39:04
Birds: Endothermic, Bones, and Feathers
40:15
Mammals
42:33
Mammals Overview
42:35
Diaphragm and Heart
42:57
Diphydont
43:44
Synapsids
44:41
Monotremes
46:36
Monotremes
46:37
Marsupials
47:12
Marsupials: Definition and Examples
47:16
Convergent Evolution
48:09
Eutherians (Placental Mammals)
49:42
Placenta
49:43
Order Carnivora
50:48
Order Raodentia
51:00
Order Cetaceans
51:14
Primates
51:41
Primates Overview
51:42
Nails and Hands
51:58
Vision
52:51
Social Care for Young
53:28
Brain
53:43
Example 1: Distinguishing Characteristics of Chordates
54:33
Example 2: Match Description to Correct Term
55:56
Example 3: Bird's Anatomy
57:38
Example 4: Vertebrate Animal, Marine Environment, and Ectothermic
59:14
Section 9: Plants
Seedless Plants

34m 31s

Intro
0:00
Origin and Classification of Plants
0:06
Origin and Classification of Plants
0:07
Non-Vascular vs. Vascular Plants
1:29
Seedless Vascular & Seed Plants
2:28
Angiosperms & Gymnosperms
2:50
Alternation of Generations
3:54
Alternation of Generations
3:55
Bryophytes
7:58
Overview of Bryrophytes
7:59
Example: Moss Gametophyte
9:29
Example: Moss Sporophyte
9:50
Moss Life Cycle
10:12
Moss Life Cycle
10:13
Seedless Vascular Plants
13:23
Vascular Structures: Cell Walls, and Lignin
13:24
Homosporous
17:11
Heterosporous
17:48
Adaptations to Life on land
21:10
Adaptation 1: Cell Walls
21:38
Adaptation 2: Vascular Plants
21:59
Adaptation 3 : Xylem & Phloem
22:31
Adaptation 4: Seeds
23:07
Adaptation 5: Pollen
23:35
Adaptation 6: Stomata
24:45
Adaptation 7: Reduced Gametophyte Generation
25:32
Example 1: Bryophytes
26:39
Example 2: Sporangium, Lignin, Gametophyte, and Antheridium
28:34
Example 3: Adaptations to Life on Land
29:47
Example 4: Life Cycle of Plant
32:06
Plant Structure

1h 1m 21s

Intro
0:00
Plant Tissue
0:05
Dermal Tissue
0:15
Vascular Tissue
0:39
Ground Tissue
1:31
Cell Types in Plants
2:14
Parenchyma Cells
2:24
Collenchyma Cells
3:21
Sclerenchyma Cells
3:59
Xylem
5:04
Xylem: Tracheids and Vessel Elements
6:12
Gymnosperms vs. Angiosperms
7:53
Phloem
8:37
Phloem: Structures and Function
8:38
Sieve-Tube Elements
8:45
Companion Cells & Sieve Plates
9:11
Roots
10:08
Taproots & Fibrous
10:09
Aerial Roots & Prop Roots
11:41
Structures and Functions of Root: Dicot & Monocot
13:00
Pericyle
16:57
The Nitrogen Cylce
18:05
The Nitrogen Cycle
18:06
Mycorrhizae
24:20
Mycorrhizae
24:23
Ectomycorrhiza
26:03
Endomycorrhiza
26:25
Stems
26:53
Stems
26:54
Vascular Bundles of Monocots and Dicots
28:18
Leaves
29:48
Blade & Petiole
30:13
Upper Epidermis, Lower Epidermis & Cuticle
30:39
Ground Tissue, Palisade Mesophyll, Spongy Mesophyll
31:35
Stomata Pores
33:23
Guard Cells
34:15
Vascular Tissues: Vascular Bundles and Bundle Sheath
34:46
Stomata
36:12
Stomata & Gas Exchange
36:16
Guard Cells, Flaccid, and Turgid
36:43
Water Potential
38:03
Factors for Opening Stoma
40:35
Factors Causing Stoma to Close
42:44
Overview of Plant Growth
44:23
Overview of Plant Growth
44:24
Primary Plant Growth
46:19
Apical Meristems
46:25
Root Growth: Zone of Cell Division
46:44
Root Growth: Zone of Cell Elongation
47:35
Root Growth: Zone of Cell Differentiation
47:55
Stem Growth: Leaf Primodia
48:16
Secondary Plant Growth
48:48
Secondary Plant Growth Overview
48:59
Vascular Cambium: Secondary Xylem and Phloem
49:38
Cork Cambium: Periderm and Lenticels
51:10
Example 1: Leaf Structures
53:30
Example 2: List Three Types of Plant Tissue and their Major Functions
55:13
Example 3: What are Two Factors that Stimulate the Opening or Closing of Stomata?
56:58
Example 4: Plant Growth
59:18
Gymnosperms and Angiosperms

1h 1m 51s

Intro
0:00
Seed Plants
0:22
Sporopollenin
0:58
Heterosporous: Megasporangia
2:49
Heterosporous: Microsporangia
3:19
Gymnosperms
5:20
Gymnosperms
5:21
Gymnosperm Life Cycle
7:30
Gymnosperm Life Cycle
7:31
Flower Structure
15:15
Petal & Pollination
15:48
Sepal
16:52
Stamen: Anther, Filament
17:05
Pistill: Stigma, Style, Ovule, Ovary
17:55
Complete Flowers
20:14
Angiosperm Gametophyte Formation
20:47
Male Gametophyte: Microsporocytes, Microsporangia & Meiosis
20:57
Female Gametophyte: Megasporocytes & Meiosis
24:22
Double Fertilization
25:43
Double Fertilization: Pollen Tube and Endosperm
25:44
Angiosperm Life Cycle
29:43
Angiosperm Life Cycle
29:48
Seed Structure and Development
33:37
Seed Structure and Development
33:38
Pollen Dispersal
37:53
Abiotic
38:28
Biotic
39:30
Prevention of Self-Pollination
40:48
Mechanism 1
41:08
Mechanism 2: Dioecious
41:37
Mechanism 3
42:32
Self-Incompatibility
43:08
Gametophytic Self-Incompatibility
44:38
Sporophytic Self-Incompatibility
46:50
Asexual Reproduction
48:33
Asexual Reproduction & Vegetative Propagation
48:34
Graftiry
50:19
Monocots and Dicots
51:34
Monocots vs.Dicots
51:35
Example 1: Double Fertilization
54:43
Example 2: Mechanisms of Self-Fertilization
56:02
Example 3: Monocots vs. Dicots
58:11
Example 4: Flower Structures
1:00:11
Transport of Nutrients and Water in Plants

40m 30s

Intro
0:00
Review of Plant Cell Structure
0:14
Cell Wall, Plasma Membrane, Middle lamella, and Cytoplasm
0:15
Plasmodesmata, Chloroplasts, and Central Vacuole
3:24
Water Absorption by Plants
4:28
Root Hairs and Mycorrhizae
4:30
Osmosis and Water Potential
5:41
Apoplast and Symplast Pathways
10:01
Apoplast and Symplast Pathways
10:02
Xylem Structure
21:02
Tracheids and Vessel Elements
21:03
Bulk Flow
23:00
Transpiration
23:26
Cohesion
25:10
Adhesion
26:10
Phloem Structure
27:25
Pholem
27:26
Sieve-Tube Elements
27:48
Companion Cells
28:17
Translocation
28:42
Sugar Source and Sugar Sink Overview
28:43
Example of Sugar Sink
30:01
Example of Sugar Source
30:48
Example 1: Match the Following Terms to their Description
33:17
Example 2: Water Potential
34:58
Example 3: Bulk Flow
36:56
Example 4: Sugar Sink and Sugar Source
38:33
Plant Hormones and Tropisms

48m 10s

Intro
0:00
Plant Cell Signaling
0:17
Plant Cell Signaling Overview
0:18
Step 1: Reception
1:03
Step 2: Transduction
2:32
Step 3: Response
2:58
Second Messengers
3:52
Protein Kinases
4:42
Auxins
6:14
Auxins
6:18
Indoleacetic Acid (IAA)
7:23
Cytokinins and Gibberellins
11:10
Cytokinins: Apical Dominance & Delay of Aging
11:16
Gibberellins: 'Bolting'
13:51
Ethylene
15:33
Ethylene
15:34
Positive Feedback
15:46
Leaf Abscission
18:05
Mechanical Stress: Triple Response
19:36
Abscisic Acid
21:10
Abscisic Acid
21:15
Tropisms
23:11
Positive Tropism
23:50
Negative Tropism
24:07
Statoliths
26:21
Phytochromes and Photoperiodism
27:48
Phytochromes: PR and PFR
27:56
Circadian Rhythms
32:06
Photoperiod
33:13
Photoperiodism
33:38
Gerner & Allard
34:35
Short-Day Plant
35:22
Long-Day Plant
37:00
Example 1: Plant Hormones
41:28
Example 2: Cytokinins & Gibberellins
43:00
Example 3: Match the Following Terms to their Description
44:46
Example 4: Hormones & Cell Response
46:14
Section 10: Animal Structure and Physiology
The Respiratory System

48m 14s

Intro
0:00
Gas Exchange in Animals
0:17
Respiration
0:19
Ventilation
1:09
Characteristics of Respiratory Surfaces
1:53
Gas Exchange in Aquatic Animals
3:05
Simple Aquatic Animals
3:06
Gills & Gas Exchange in Complex Aquatic Animals
3:49
Countercurrent Exchange
6:12
Gas Exchange in Terrestrial Animals
13:46
Earthworms
14:07
Internal Respiratory
15:35
Insects
16:55
Circulatory Fluid
19:06
The Human Respiratory System
21:21
Nasal Cavity, Pharynx, Larynx, and Epiglottis
21:50
Bronchus, Bronchiole, Trachea, and Alveoli
23:38
Pulmonary Surfactants
28:05
Circulatory System: Hemoglobin
29:13
Ventilation
30:28
Inspiration/Expiration: Diaphragm, Thorax, and Abdomen
30:33
Breathing Control Center: Regulation of pH
34:34
Example 1: Tracheal System in Insects
39:08
Example 2: Countercurrent Exchange
42:09
Example 3: Respiratory System
44:10
Example 4: Diaphragm, Ventilation, pH, and Regulation of Breathing
45:31
The Circulatory System

1h 20m 21s

Intro
0:00
Types of Circulatory Systems
0:07
Circulatory System Overview
0:08
Open Circulatory System
3:19
Closed Circulatory System
5:58
Blood Vessels
7:51
Arteries
8:16
Veins
10:01
Capillaries
12:35
Vasoconstriction and Vasodilation
13:10
Vasoconstriction
13:11
Vasodilation
13:47
Thermoregulation
14:32
Blood
15:53
Plasma
15:54
Cellular Component: Red Blood Cells
17:41
Cellular Component: White Blood Cells
20:18
Platelets
21:14
Blood Types
21:35
Clotting
27:04
Blood, Fibrin, and Clotting
27:05
Hemophilia
30:26
The Heart
31:09
Structures and Functions of the Heart
31:19
Pulmonary and Systemic Circulation
40:20
Double Circuit: Pulmonary Circuit and Systemic Circuit
40:21
The Cardiac Cycle
42:35
The Cardiac Cycle
42:36
Autonomic Nervous System
50:00
Hemoglobin
51:25
Hemoglobin & Hemocyanin
51:26
Oxygen-Hemoglobin Dissociation Curve
55:30
Oxygen-Hemoglobin Dissociation Curve
55:44
Transport of Carbon Dioxide
1:06:31
Transport of Carbon Dioxide
1:06:37
Example 1: Pathway of Blood
1:12:48
Example 2: Oxygenated Blood, Pacemaker, and Clotting
1:15:24
Example 3: Vasodilation and Vasoconstriction
1:16:19
Example 4: Oxygen-Hemoglobin Dissociation Curve
1:18:13
The Digestive System

56m 11s

Intro
0:00
Introduction to Digestion
0:07
Digestive Process
0:08
Intracellular Digestion
0:45
Extracellular Digestion
1:44
Types of Digestive Tracts
2:08
Gastrovascular Cavity
2:09
Complete Gastrointestinal Tract (Alimentary Canal)
3:54
'Crop'
4:43
The Human Digestive System
5:41
Structures of the Human Digestive System
5:47
The Oral Cavity and Esophagus
7:47
Mechanical & Chemical Digestion
7:48
Salivary Glands
8:55
Pharynx and Epigloltis
9:43
Peristalsis
11:35
The Stomach
12:57
Lower Esophageal Sphincter
13:00
Gastric Gland, Parietal Cells, and Pepsin
14:32
Mucus Cell
15:48
Chyme & Pyloric Sphincter
17:32
The Pancreas
18:31
Endocrine and Exocrine
19:03
Amylase
20:05
Proteases
20:51
Lipases
22:20
The Liver
23:08
The Liver & Production of Bile
23:09
The Small Intestine
24:37
The Small Intestine
24:38
Duodenum
27:44
Intestinal Enzymes
28:41
Digestive Enzyme
33:30
Site of Production: Mouth
33:43
Site of Production: Stomach
34:03
Site of Production: Pancreas
34:16
Site of Production: Small Intestine
36:18
Absorption of Nutrients
37:51
Absorption of Nutrients: Jejunum and Ileum
37:52
The Large Intestine
44:52
The Large Intestine: Colon, Cecum, and Rectum
44:53
Regulation of Digestion by Hormones
46:55
Gastrin
47:21
Secretin
47:50
Cholecystokinin (CCK)
48:00
Example 1: Intestinal Cell, Bile, and Digestion of Fats
48:29
Example 2: Matching
51:06
Example 3: Digestion and Absorption of Starch
52:18
Example 4: Large Intestine and Gastric Fluids
54:52
The Excretory System

1h 12m 14s

Intro
0:00
Nitrogenous Wastes
0:08
Nitrogenous Wastes Overview
0:09
NH3
0:39
Urea
2:43
Uric Acid
3:31
Osmoregulation
4:56
Osmoregulation
5:05
Saltwater Fish vs. Freshwater Fish
8:58
Types of Excretory Systems
13:42
Protonephridia
13:50
Metanephridia
16:15
Malpighian Tubule
19:05
The Human Excretory System
20:45
Kidney, Ureter, bladder, Urethra, Medula, and Cortex
20:53
Filtration, Reabsorption and Secretion
22:53
Filtration
22:54
Reabsorption
24:16
Secretion
25:20
The Nephron
26:23
The Nephron
26:24
The Nephron, cont.
41:45
Descending Loop of Henle
41:46
Ascending Loop of Henle
45:45
Antidiuretic Hormone
54:30
Antidiuretic Hormone (ADH)
54:31
Aldosterone
58:58
Aldosterone
58:59
Example 1: Nephron of an Aquatic Mammal
1:04:21
Example 2: Uric Acid & Saltwater Fish
1:06:36
Example 3: Nephron
1:09:14
Example 4: Gastrointestinal Infection
1:10:41
The Endocrine System

51m 12s

Intro
0:00
The Endocrine System Overview
0:07
Thyroid
0:08
Exocrine
1:56
Pancreas
2:44
Paracrine Signaling
4:06
Pheromones
5:15
Mechanisms of Hormone Action
6:06
Reception, Transduction, and Response
7:06
Classes of Hormone
10:05
Negative Feedback: Testosterone Example
12:16
The Pancreas
15:11
The Pancreas & islets of Langerhan
15:12
Insulin
16:02
Glucagon
17:28
The Anterior Pituitary
19:25
Thyroid Stimulating Hormone
20:24
Adrenocorticotropic Hormone
21:16
Follide Stimulating Hormone
22:04
Luteinizing Hormone
22:45
Growth Hormone
23:45
Prolactin
24:24
Melanocyte Stimulating Hormone
24:55
The Hypothalamus and Posterior Pituitary
25:45
Hypothalamus, Oxytocin, Antidiuretic Hormone (ADH), and Posterior Pituitary
25:46
The Adrenal Glands
31:20
Adrenal Cortex
31:56
Adrenal Medulla
34:29
The Thyroid
35:54
Thyroxine
36:09
Calcitonin
40:27
The Parathyroids
41:44
Parathyroids Hormone (PTH)
41:45
The Ovaries and Testes
43:32
Estrogen, Progesterone, and Testosterone
43:33
Example 1: Match the Following Hormones with their Descriptions
45:38
Example 2: Pancreas, Endocrine Organ & Exocrine Organ
47:06
Example 3: Insulin and Glucagon
48:28
Example 4: Increased Level of Cortisol in Blood
50:25
The Nervous System

1h 10m 38s

Intro
0:00
Types of Nervous Systems
0:28
Nerve Net
0:37
Flatworm
1:07
Cephalization
1:52
Arthropods
2:44
Echinoderms
3:11
Nervous System Organization
3:40
Nervous System Organization Overview
3:41
Automatic Nervous System: Sympathetic & Parasympathetic
4:42
Neuron Structure
6:57
Cell Body & Dendrites
7:16
Axon & Axon Hillock
8:20
Synaptic Terminals, Mylenin, and Nodes of Ranvier
9:01
Pre-synaptic and Post-synaptic Cells
10:16
Pre-synaptic Cells
10:17
Post-synaptic Cells
11:05
Types of Neurons
11:50
Sensory Neurons
11:54
Motor Neurons
13:12
Interneurons
14:24
Resting Potential
15:14
Membrane Potential
15:25
Resting Potential: Chemical Gradient
16:06
Resting Potential: Electrical Gradient
19:18
Gated Ion Channels
24:40
Voltage-Gated & Ligand-Gated Ion Channels
24:48
Action Potential
30:09
Action Potential Overview
30:10
Step 1
32:07
Step 2
32:17
Step 3
33:12
Step 4
35:14
Step 5
36:39
Action Potential Transmission
39:04
Action Potential Transmission
39:05
Speed of Conduction
41:19
Saltatory Conduction
42:58
The Synapse
44:17
The Synapse: Presynaptic & Postsynaptic Cell
44:31
Examples of Neurotransmitters
50:05
Brain Structure
51:57
Meniges
52:19
Cerebrum
52:56
Corpus Callosum
53:13
Gray & White Matter
53:38
Cerebral Lobes
55:35
Cerebellum
56:00
Brainstem
56:30
Medulla
56:51
Pons
57:22
Midbrain
57:55
Thalamus
58:25
Hypothalamus
58:58
Ventricles
59:51
The Spinal Cord
1:00:29
Sensory Stimuli
1:00:30
Reflex Arc
1:01:41
Example 1: Automatic Nervous System
1:04:38
Example 2: Synaptic Terminal and the Release of Neurotransmitters
1:06:22
Example 3: Volted-Gated Ion Channels
1:08:00
Example 4: Neuron Structure
1:09:26
Musculoskeletal System

39m 29s

Intro
0:00
Skeletal System Types and Function
0:30
Skeletal System
0:31
Exoskeleton
1:34
Endoskeleton
2:32
Skeletal System Components
2:55
Bone
3:06
Cartilage
5:04
Tendons
6:18
Ligaments
6:34
Skeletal Muscle
6:52
Skeletal Muscle
7:24
Sarcomere
9:50
The Sliding Filament Theory
13:12
The Sliding Filament Theory: Muscle Contraction
13:13
The Neuromuscular Junction
17:24
The Neuromuscular Junction: Motor Neuron & Muscle Fiber
17:26
Sarcolemma, Sarcoplasmic
21:54
Tropomyosin & Troponin
23:35
Summation and Tetanus
25:26
Single Twitch, Summation of Two Twitches, and Tetanus
25:27
Smooth Muscle
28:50
Smooth Muscle
28:58
Cardiac Muscle
30:40
Cardiac Muscle
30:42
Summary of Muscle Types
32:07
Summary of Muscle Types
32:08
Example 1: Contraction and Skeletal Muscle
33:15
Example 2: Skeletal Muscle and Smooth Muscle
36:23
Example 3: Muscle Contraction, Bone, and Nonvascularized Connective Tissue
37:31
Example 4: Sarcomere
38:17
The Immune System

1h 24m 28s

Intro
0:00
The Lymphatic System
0:16
The Lymphatic System Overview
0:17
Function 1
1:23
Function 2
2:27
Barrier Defenses
3:41
Nonspecific vs. Specific Immune Defenses
3:42
Barrier Defenses
5:12
Nonspecific Cellular Defenses
7:50
Nonspecific Cellular Defenses Overview
7:53
Phagocytes
9:29
Neutrophils
11:43
Macrophages
12:15
Natural Killer Cells
12:55
Inflammatory Response
14:19
Complement
18:16
Interferons
18:40
Specific Defenses - Acquired Immunity
20:12
T lymphocytes and B lymphocytes
20:13
B Cells
23:35
B Cells & Humoral Immunity
23:41
Clonal Selection
29:50
Clonal Selection
29:51
Primary Immune Response
34:28
Secondary Immune Response
35:31
Cytotoxic T Cells
38:41
Helper T Cells
39:20
Major Histocompatibility Complex Molecules
40:44
Major Histocompatibility Complex Molecules
40:55
Helper T Cells
52:36
Helper T Cells
52:37
Mechanisms of Antibody Action
59:00
Mechanisms of Antibody Action
59:01
Opsonization
1:00:01
Complement System
1:01:57
Classes of Antibodies
1:02:45
IgM
1:03:01
IgA
1:03:17
IgG
1:03:53
IgE
1:04:10
Passive and Active Immunity
1:05:00
Passive Immunity
1:05:01
Active Immunity
1:07:49
Recognition of Self and Non-Self
1:09:32
Recognition of Self and Non-Self
1:09:33
Self-Tolerance & Autoimmune Diseases
1:10:50
Immunodeficiency
1:13:27
Immunodeficiency
1:13:28
Chemotherapy
1:13:56
AID
1:14:27
Example 1: Match the Following Terms with their Descriptions
1:15:26
Example 2: Three Components of Non-specific Immunity
1:17:59
Example 3: Immunodeficient
1:21:19
Example 4: Self-tolerance and Autoimmune Diseases
1:23:07
Section 11: Animal Reproduction and Development
Reproduction

1h 1m 41s

Intro
0:00
Asexual Reproduction
0:17
Fragmentation
0:53
Fission
1:54
Parthenogenesis
2:38
Sexual Reproduction
4:00
Sexual Reproduction
4:01
Hermaphrodite
8:08
The Male Reproduction System
8:54
Seminiferous Tubules & Leydig Cells
8:55
Epididymis
9:48
Seminal Vesicle
11:19
Bulbourethral
12:37
The Female Reproductive System
13:25
Ovaries
13:28
Fallopian
14:50
Endometrium, Uterus, Cilia, and Cervix
15:03
Mammary Glands
16:44
Spermatogenesis
17:08
Spermatogenesis
17:09
Oogenesis
21:01
Oogenesis
21:02
The Menstrual Cycle
27:56
The Menstrual Cycle: Ovarian and Uterine Cycle
27:57
Summary of the Ovarian and Uterine Cycles
42:54
Ovarian
42:55
Uterine
44:51
Oxytocin and Prolactin
46:33
Oxytocin
46:34
Prolactin
47:00
Regulation of the Male Reproductive System
47:28
Hormones: GnRH, LH, FSH, and Testosterone
47:29
Fertilization
50:11
Fertilization
50:12
Structures of Egg
50:28
Acrosomal Reaction
51:36
Cortical Reaction
53:09
Example 1: List Three Differences between Spermatogenesis and oogenesis
55:36
Example 2: Match the Following Terms to their Descriptions
57:34
Example 3: Pregnancy and the Ovarian Cycle
58:44
Example 4: Hormone
1:00:43
Development

50m 5s

Intro
0:00
Cleavage
0:31
Cleavage
0:32
Meroblastic
2:06
Holoblastic Cleavage
3:23
Protostomes
4:34
Deuterostomes
5:13
Totipotent
5:52
Blastula Formation
6:42
Blastula
6:46
Gastrula Formation
8:12
Deuterostomes
11:02
Protostome
11:44
Ectoderm
12:17
Mesoderm
12:55
Endoderm
13:40
Cytoplasmic Determinants
15:19
Cytoplasmic Determinants
15:23
The Bird Embryo
22:52
Cleavage
23:35
Blastoderm
23:55
Primitive Streak
25:38
Migration and Differentiation
27:09
Extraembryonic Membranes
28:33
Extraembryonic Membranes
28:34
Chorion
30:02
Yolk Sac
30:36
Allantois
31:04
The Mammalian Embryo
32:18
Cleavage
32:28
Blastocyst
32:44
Trophoblast
34:37
Following Implantation
35:48
Organogenesis
37:04
Organogenesis, Notochord and Neural Tube
37:05
Induction
40:15
Induction
40:39
Fate Mapping
41:40
Example 1: Processes and Stages of Embryological Development
42:49
Example 2: Transplanted Cells
44:33
Example 3: Germ Layer
46:41
Example 4: Extraembryonic Membranes
47:28
Section 12: Animal Behavior
Animal Behavior

47m 48s

Intro
0:00
Introduction to Animal Behavior
0:05
Introduction to Animal Behavior
0:06
Ethology
1:04
Proximate Cause & Ultimate Cause
1:46
Fixed Action Pattern
3:07
Sign Stimulus
3:40
Releases and Example
3:55
Exploitation and Example
7:23
Learning
8:56
Habituation, Associative Learning, and Imprinting
8:57
Habituation
10:03
Habituation: Definition and Example
10:04
Associative Learning
11:47
Classical
12:19
Operant Conditioning
13:40
Positive & Negative Reinforcement
14:59
Positive & Negative Punishment
16:13
Extinction
17:28
Imprinting
17:47
Imprinting: Definition and Example
17:48
Social Behavior
20:12
Cooperation
20:38
Agonistic
21:37
Dorminance Heirarchies
23:23
Territoriality
24:08
Altruism
24:55
Communication
26:56
Communication
26:57
Mating
32:38
Mating Overview
32:40
Promiscuous
33:13
Monogamous
33:32
Polygamous
33:48
Intrasexual
34:22
Intersexual Selection
35:08
Foraging
36:08
Optimal Foraging Model
36:39
Foraging
37:47
Movement
39:12
Kinesis
39:20
Taxis
40:17
Migration
40:54
Lunar Cycles
42:02
Lunar Cycles
42:08
Example 1: Types of Conditioning
43:19
Example 2: Match the Following Terms to their Descriptions
44:12
Example 3: How is the Optimal Foraging Model Used to Explain Foraging Behavior
45:47
Example 4: Learning
46:54
Section 13: Ecology
Biomes

58m 49s

Intro
0:00
Ecology
0:08
Ecology
0:14
Environment
0:22
Integrates
1:41
Environment Impacts
2:20
Population and Distribution
3:20
Population
3:21
Range
4:50
Potential Range
5:10
Abiotic
5:46
Biotic
6:22
Climate
7:55
Temperature
8:40
Precipitation
10:00
Wind
10:37
Sunlight
10:54
Macroclimates & Microclimates
11:31
Other Abiotic Factors
12:20
Geography
12:28
Water
13:17
Soil and Rocks
13:48
Sunlight
14:42
Sunlight
14:43
Seasons
15:43
June Solstice, December Solstice, March Equinox, and September Equinox
15:44
Tropics
19:00
Seasonability
19:39
Wind and Weather Patterns
20:44
Vertical Circulation
20:51
Surface Wind Patterns
25:18
Local Climate Effects
26:51
Local Climate Effects
26:52
Terrestrial Biomes
30:04
Biome
30:05
Forest
31:02
Tropical Forest
32:00
Tropical Forest
32:01
Temperate Broadleaf Forest
32:55
Temperate Broadleaf Forest
32:56
Coniferous/Taiga Forest
34:10
Coniferous/Taiga Forest
34:11
Desert
36:05
Desert
36:06
Grassland
37:45
Grassland
37:46
Tundra
40:09
Tundra
40:10
Freshwater Biomes
42:25
Freshwater Biomes: Zones
42:27
Eutrophic Lakes
44:24
Oligotrophic Lakes
45:01
Lakes Turnover
46:03
Rivers
46:51
Wetlands
47:40
Estuary
48:11
Marine Biomes
48:45
Marine Biomes: Zones
48:46
Example 1: Diversity of Life
52:18
Example 2: Marine Biome
53:08
Example 3: Season
54:20
Example 4: Biotic vs. Abiotic
55:54
Population

41m 16s

Intro
0:00
Population
0:07
Size 'N'
0:16
Density
0:41
Dispersion
1:01
Measure Population: Count Individuals, Sampling, and Proxymeasure
2:26
Mortality
7:29
Mortality and Survivorship
7:30
Age Structure Diagrams
11:52
Expanding with Rapid Growth, Expanding, and Stable
11:58
Population Growth
15:39
Biotic Potential & Exponential Growth
15:43
Logistic Population Growth
19:07
Carrying Capacity (K)
19:18
Limiting Factors
20:55
Logistic Model and Oscillation
22:55
Logistic Model and Oscillation
22:56
Changes to the Carrying Capacity
24:36
Changes to the Carrying Capacity
24:37
Growth Strategies
26:07
'r-selected' or 'r-strategist'
26:23
'K-selected' or 'K-strategist'
27:47
Human Population
30:15
Human Population and Exponential Growth
30:21
Case Study - Lynx and Hare
31:54
Case Study - Lynx and Hare
31:55
Example 1: Estimating Population Size
34:35
Example 2: Population Growth
36:45
Example 3: Carrying Capacity
38:17
Example 4: Types of Dispersion
40:15
Communities

1h 6m 26s

Intro
0:00
Community
0:07
Ecosystem
0:40
Interspecific Interactions
1:14
Competition
2:45
Competition Overview
2:46
Competitive Exclusion
3:57
Resource Partitioning
4:45
Character Displacement
6:22
Predation
7:46
Predation
7:47
True Predation
8:05
Grazing/ Herbivory
8:39
Predator Adaptation
10:13
Predator Strategies
10:22
Physical Features
11:02
Prey Adaptation
12:14
Prey Adaptation
12:23
Aposematic Coloration
13:35
Batesian Mimicry
14:32
Size
15:42
Parasitism
16:48
Symbiotic Relationship
16:54
Ectoparasites
18:31
Endoparasites
18:53
Hyperparisitism
19:21
Vector
20:08
Parasitoids
20:54
Mutualism
21:23
Resource - Resource mutualism
21:34
Service - Resource Mutualism
23:31
Service - Service Mutualism: Obligate & Facultative
24:23
Commensalism
26:01
Commensalism
26:03
Symbiosis
27:31
Trophic Structure
28:35
Producers & Consumers: Autotrophs & Heterotrophs
28:36
Food Chain
33:26
Producer & Consumers
33:38
Food Web
39:01
Food Web
39:06
Significant Species within Communities
41:42
Dominant Species
41:50
Keystone Species
42:44
Foundation Species
43:41
Community Dynamics and Disturbances
44:31
Disturbances
44:33
Duration
47:01
Areal Coverage
47:22
Frequency
47:48
Intensity
48:04
Intermediate Level of Disturbance
48:20
Ecological Succession
50:29
Primary and Secondary Ecological Succession
50:30
Example 1: Competition Situation & Outcome
57:18
Example 2: Food Chains
1:00:08
Example 3: Ecological Units
1:02:44
Example 4: Disturbances & Returning to the Original Climax Community
1:04:30
Energy and Ecosystems

57m 42s

Intro
0:00
Ecosystem: Biotic & Abiotic Components
0:15
First Law of Thermodynamics & Energy Flow
0:40
Gross Primary Productivity (GPP)
3:52
Net Primary Productivity (NPP)
4:50
Biogeochemical Cycles
7:16
Law of Conservation of Mass & Biogeochemical Cycles
7:17
Water Cycle
10:55
Water Cycle
10:57
Carbon Cycle
17:52
Carbon Cycle
17:53
Nitrogen Cycle
22:40
Nitrogen Cycle
22:41
Phosphorous Cycle
29:34
Phosphorous Cycle
29:35
Climate Change
33:20
Climate Change
33:21
Eutrophication
39:38
Nitrogen
40:34
Phosphorous
41:29
Eutrophication
42:55
Example 1: Energy and Ecosystems
45:28
Example 2: Atmospheric CO2
48:44
Example 3: Nitrogen Cycle
51:22
Example 4: Conversion of a Forest near a Lake to Farmland
53:20
Section 14: Laboratory Review
Laboratory Review

2h 4m 30s

Intro
0:00
Lab 1: Diffusion and Osmosis
0:09
Lab 1: Diffusion and Osmosis
0:10
Lab 1: Water Potential
11:55
Lab 1: Water Potential
11:56
Lab 2: Enzyme Catalysis
18:30
Lab 2: Enzyme Catalysis
18:31
Lab 3: Mitosis and Meiosis
27:40
Lab 3: Mitosis and Meiosis
27:41
Lab 3: Mitosis and Meiosis
31:50
Ascomycota Life Cycle
31:51
Lab 4: Plant Pigments and Photosynthesis
40:36
Lab 4: Plant Pigments and Photosynthesis
40:37
Lab 5: Cell Respiration
49:56
Lab 5: Cell Respiration
49:57
Lab 6: Molecular Biology
55:06
Lab 6: Molecular Biology & Transformation 1st Part
55:07
Lab 6: Molecular Biology
1:01:16
Lab 6: Molecular Biology 2nd Part
1:01:17
Lab 7: Genetics of Organisms
1:07:32
Lab 7: Genetics of Organisms
1:07:33
Lab 7: Chi-square Analysis
1:13:00
Lab 7: Chi-square Analysis
1:13:03
Lab 8: Population Genetics and Evolution
1:20:41
Lab 8: Population Genetics and Evolution
1:20:42
Lab 9: Transpiration
1:24:02
Lab 9: Transpiration
1:24:03
Lab 10: Physiology of the Circulatory System
1:31:05
Lab 10: Physiology of the Circulatory System
1:31:06
Lab 10: Temperature and Metabolism in Ectotherms
1:38:25
Lab 10: Temperature and Metabolism in Ectotherms
1:38:30
Lab 11: Animal Behavior
1:40:52
Lab 11: Animal Behavior
1:40:53
Lab 12: Dissolved Oxygen & Aquatic Primary Productivity
1:45:36
Lab 12: Dissolved Oxygen & Aquatic Primary Productivity
1:45:37
Lab 12: Primary Productivity
1:49:06
Lab 12: Primary Productivity
1:49:07
Example 1: Chi-square Analysis
1:56:31
Example 2: Mitosis
1:59:28
Example 3: Transpiration of Plants
2:00:27
Example 4: Population Genetic
2:01:16
Section 15: The AP Biology Test
Understanding the Basics

13m 2s

Intro
0:00
AP Biology Structure
0:18
Section I
0:31
Section II
1:16
Scoring
2:04
The Four 'Big Ideas'
3:51
Process of Evolution
4:37
Biological Systems Utilize
4:44
Living Systems
4:55
Biological Systems Interact
5:03
Items to Bring to the Test
7:56
Test Taking Tips
9:53
Section 16: Practice Test (Barron's 4th Edition)
AP Biology Practice Exam: Section I, Part A, Multiple Choice Questions 1-31

1h 4m 29s

Intro
0:00
AP Biology Practice Exam
0:14
Multiple Choice 1
0:40
Multiple Choice 2
2:27
Multiple Choice 3
4:30
Multiple Choice 4
6:43
Multiple Choice 5
9:27
Multiple Choice 6
11:32
Multiple Choice 7
12:54
Multiple Choice 8
14:42
Multiple Choice 9
17:06
Multiple Choice 10
18:42
Multiple Choice 11
20:49
Multiple Choice 12
23:23
Multiple Choice 13
26:20
Multiple Choice 14
27:52
Multiple Choice 15
28:44
Multiple Choice 16
33:07
Multiple Choice 17
35:31
Multiple Choice 18
39:43
Multiple Choice 19
40:37
Multiple Choice 20
42:47
Multiple Choice 21
45:58
Multiple Choice 22
49:49
Multiple Choice 23
53:44
Multiple Choice 24
55:12
Multiple Choice 25
55:59
Multiple Choice 26
56:50
Multiple Choice 27
58:08
Multiple Choice 28
59:54
Multiple Choice 29
1:01:36
Multiple Choice 30
1:02:31
Multiple Choice 31
1:03:50
AP Biology Practice Exam: Section I, Part A, Multiple Choice Questions 32-63

50m 44s

Intro
0:00
AP Biology Practice Exam
0:14
Multiple Choice 32
0:27
Multiple Choice 33
4:14
Multiple Choice 34
5:12
Multiple Choice 35
6:51
Multiple Choice 36
10:46
Multiple Choice 37
11:27
Multiple Choice 38
12:17
Multiple Choice 39
13:49
Multiple Choice 40
17:02
Multiple Choice 41
18:27
Multiple Choice 42
19:35
Multiple Choice 43
21:10
Multiple Choice 44
23:35
Multiple Choice 45
25:00
Multiple Choice 46
26:20
Multiple Choice 47
28:40
Multiple Choice 48
30:14
Multiple Choice 49
31:24
Multiple Choice 50
32:45
Multiple Choice 51
33:41
Multiple Choice 52
34:40
Multiple Choice 53
36:12
Multiple Choice 54
38:06
Multiple Choice 55
38:37
Multiple Choice 56
40:00
Multiple Choice 57
41:18
Multiple Choice 58
43:12
Multiple Choice 59
44:25
Multiple Choice 60
45:02
Multiple Choice 61
46:10
Multiple Choice 62
47:54
Multiple Choice 63
49:01
AP Biology Practice Exam: Section I, Part B, Grid In

21m 52s

Intro
0:00
AP Biology Practice Exam
0:17
Grid In Question 1
0:29
Grid In Question 2
3:49
Grid In Question 3
11:04
Grid In Question 4
13:18
Grid In Question 5
17:01
Grid In Question 6
19:30
AP Biology Practice Exam: Section II, Long Free Response Questions

31m 22s

Intro
0:00
AP Biology Practice Exam
0:18
Free Response 1
0:29
Free Response 2
20:47
AP Biology Practice Exam: Section II, Short Free Response Questions

24m 41s

Intro
0:00
AP Biology Practice Exam
0:15
Free Response 3
0:26
Free Response 4
5:21
Free Response 5
8:25
Free Response 6
11:38
Free Response 7
14:48
Free Response 8
22:14
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Lecture Comments (4)

0 answers

Post by Helen He on April 9, 2021

I have Barron's 7th Edition.  Does it have the same practice exam please?

1 answer

Last reply by: Chrystal Wang
Mon Oct 7, 2019 8:41 PM

Post by Kunj Kashyap on May 12, 2017

where can I find the questions?????????

0 answers

Post by Connor McRobert on May 9, 2015

Could you please be better prepared in each lecture for the future?

AP Biology Practice Exam: Section I, Part A, Multiple Choice Questions 1-31

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • AP Biology Practice Exam 0:14
  • Multiple Choice 1 0:40
  • Multiple Choice 2 2:27
  • Multiple Choice 3 4:30
  • Multiple Choice 4 6:43
  • Multiple Choice 5 9:27
  • Multiple Choice 6 11:32
  • Multiple Choice 7 12:54
  • Multiple Choice 8 14:42
  • Multiple Choice 9 17:06
  • Multiple Choice 10 18:42
  • Multiple Choice 11 20:49
  • Multiple Choice 12 23:23
  • Multiple Choice 13 26:20
  • Multiple Choice 14 27:52
  • Multiple Choice 15 28:44
  • Multiple Choice 16 33:07
  • Multiple Choice 17 35:31
  • Multiple Choice 18 39:43
  • Multiple Choice 19 40:37
  • Multiple Choice 20 42:47
  • Multiple Choice 21 45:58
  • Multiple Choice 22 49:49
  • Multiple Choice 23 53:44
  • Multiple Choice 24 55:12
  • Multiple Choice 25 55:59
  • Multiple Choice 26 56:50
  • Multiple Choice 27 58:08
  • Multiple Choice 28 59:54
  • Multiple Choice 29 1:01:36
  • Multiple Choice 30 1:02:31
  • Multiple Choice 31 1:03:50

Transcription: AP Biology Practice Exam: Section I, Part A, Multiple Choice Questions 1-31

Welcome to Educator.com. I am Dr. Carleen Eaton.0000

In today's lesson, I am going to be reviewing a practice AP Biology Exam.0005

And I will be starting with section 1, part A, multiple choice questions.0010

You can find the questions written out in Barron's AP Biology, 4th Edition by Deborah Goldberg, and I will be reviewing model test 1.0016

So, I am not going to read out each question. You can follow along in the book.0030

But I am going to review the information and explain it and how to get to the correct answer.0033

Question 1 discusses chemical messengers, hormones, specifically, testosterone which is a steroid hormone.0045

And you are given a sketch of the structure of this hormone, and because it is a steroid hormone, it is a derivative of cholesterol.0053

And cholesterol has a characteristic structure of four linked hydrocarbon rings.0061

And then, in this question, you are supposed to pick the statement that explains an action from testosterone.0067

So, looking at the first answer A, it discusses binding to a cell surface receptor.0077

However, because testosterone is a steroid hormone, it is actually able to enter the cell.0084

It is soluble to the cell membrane, and because it can enter the cell, the receptor for testosterone is in the cytoplasm.0092

It is a cytoplasmic receptor.0101

So, what happens is testosterone enters the target cell, binds to its receptor.0103

And the receptor hormone complex travels to the nucleus where that complex can turn genes on or off.0108

So, it can act directly on the DNA because it is able to enter the cell.0115

Therefore, A and B are both incorrect because they discuss binding to a cell surface receptor.0121

C is correct. It describes the action of testosterone.0128

Again, D is incorrect. It is talking about the binding cyclic-AMP.0133

Cyclic-AMP often acts as the second messenger within the cell, so the correct answer for 1 is C.0137

This second question talks about the difference between ectotherms and endotherms regarding the control of body temperature.0147

And recall that like a mouse or a human being or a horse, endotherms maintain a constant internal temperature despite changes in the environmental temperature,0156

whereas ectotherms such as lizards have body temperature that changes based on the surrounding temperature.0168

So, looking at these different graphs, in the first graph, the mouse is shown to have a constant0175

body temperature, stable body temperature despite changes in the environmental temperature.0185

What is happening with the lizard though is that as the temperature is increasing, in answer A, the lizard's0191

body temperature is decreasing which does not make sense because I would expect the lizard's temperature0199

to increase as environmental temperature increased, and that is actually what is happening in answer B.0204

In answer B, as the surrounding temperature, the ambient temperature is increasing, the lizard's temperature is increasing as well.0211

The mouse has a stable body temperature across a wide environmental temperature range which is expected, so that is the correct answer.0222

In C, again, the mouse has a stable body temperature.0230

However, it is showing that the lizard is able to maintain its body temperature across a certain temperature range.0234

And then, it goes up with the surrounding temperature, but that is not accurate depiction of the situation.0239

And then, in the final answer, the mouse has some control of its body temperature.0245

But at higher temperatures, the mouse's body temperature starts increasing, and then, the lizard's temperature is changing in sort of a stepwise fashion.0250

So, it is showing periods of stability which would be inaccurate.0258

I would not expect the lizard to be able to maintain its body temperature than have a jump-up, maintain and then a jump-up, so again, the answer is 2.0261

This next question is talking about depolarization with a presynaptic membrane.0270

So, what we are really talking about here is action potentials and the various steps in an action potential.0279

So, looking at a presynaptic cell and a postsynaptic cell, depolarization is a very early step in the generation of an action potential.0285

And what happens is when the presynaptic cell is depolarized, calcium channels open up and calcium enters the cell.0310

When calcium enters the cell, that triggers the fusion of vesicles containing neurotransmitters with the cell membrane.0324

And when those vesicles fuse, the neurotransmitters are released into the synaptic cleft.0333

So, here is the neurotransmitter, and the postsynaptic cell will contain receptors. For this neurotransmitter, the receptors will bind.0341

And that binding can stimulate the cell, trigger depolarization and the postsynaptic cell and an action potential.0353

So, I have gone through all these various steps, but what this question is asking about is really the next step after depolarization.0360

And as I mentioned, that next step would be the opening of calcium channels, voltage-gated calcium channels0367

causing in the influx of calcium into the presynaptic cell, and that is what answer C is describing.0374

The other answers, A, B and D are all describing various steps that occur in the action potential0384

and the stimulation of post synaptic cell, but they are the later steps, so the next step, again, is answer C.0393

Going on to question 4. Here is a system involving an enzyme succinate dehydrogenase and an inhibitor, malonate.0405

But we do not know what kind of inhibitor it is, and recall that there are two kinds of inhibitors.0416

In the competitive inhibitor, you have got an enzyme. So, here is the enzyme, and its active site is right here.0426

And the substrate combines the active site.0439

However, there is also an inhibitor and I will call it C for competitive inhibitor that can bind that site as well, that active site.0442

And binding by the competitive inhibitor would block binding of the substrate.0451

Non-competitive inhibitor, recall, works differently.0457

There are multiple sites on this enzyme, so there is the active site. This is where the substrate binds.0462

Then, there is the second site wherein an inhibitor combines, so N for non-competitive, and it can bind in here.0471

Binding of a non-competitive inhibitor, it causes a conformational change in the enzyme that could block binding of the substrate.0480

So, to determine what type of inhibitor malonate is, one thing that you could do would be to add a very high level of substrate.0493

So, since these two, the substrate and the inhibitor, are directly competing for the active site, if you add a lot of substrate,0505

you can look at it as it is diluting out the inhibitor, and the chances are that the substrate is going to bind rather than the competitive inhibitor.0513

So, what I would expect to happen, or the correct statement here is actually A, that if concentration of0524

substrate is increased, the rate of reaction will increase if malonate is a competitive inhibitor.0533

Now, if I were to increase substrate concentration, and it was a non-competitive inhibitor,0542

it would not affect the reaction rate because there is no competition for this site.0547

Adding substrate is not going to affect the binding of a non-competitive inhibitor over here at this distant site.0551

So, the only one that is an accurate statement here is A.0558

Question 5 gives you various graphs showing temperature and precipitation by month.0568

And try to figure out which of these various climates is going to be best for plant growth.0576

And a climate that is warm for more of the year is going to have a longer growing season, so that is one thing I am going to look for.0584

Also, since, we are given that precipitation is a limiting factor, I am going to look for a climate that has a high level of precipitation.0596

Looking at this first climate that is described, it has a cold winter.0606

So, there are some cold months in there, and plant growth is going to be very slow or minimal during those months.0611

In addition, there are some very dry months in there where precipitation drops down to zero.0619

So, A is not an optimal climate out of these. Looking at B, just right away, I am seeing that precipitation is very low throughout the year in this climate.0625

C: looking at the graph, this temperature actually goes all the way down to -10°C. Again, some cold winter months.0640

And precipitation is low during certain months, higher during others.0649

But compare that to D, D is actually the best answer because if you are looking for what is going to give a good growing season, there is a stable0655

relatively warm temperature about 25 or so degree Celsius throughout the year and high levels of precipitation ranging from about a 100 all the way up to 400.0664

So, those are both very good to allow for plant growth, the warm stable temperature throughout the year and high levels of precipitation.0679

So, the answer to 5 is D.0688

Another graph in question 6, and in this one, we are being asked about photosynthesis.0692

And in the graph, what you can see is that as light intensity increases, the rate of photosynthesis increases to a certain point.0700

After a certain point, even if you increase the intensity of the light, the rate of photosynthesis remains stable.0709

So, let's figure out the explanation for this.0717

Really, looking at the graph, the only one that fits is D because the explanation0723

here is fitting an idea of the rate increasing as light increases and then, levelling off.0731

And that levelling off can be explained by the fact that the light harvesting apparatus is maxed out.0738

It has been saturated so that even if you provide greater light intensity, the cell machinery cannot work any faster, so it is D.0743

These other answers are referring to photosynthesis stopping or slowing down.0756

And it is actually not stopping nor is the rate decreasing. The rate is actually just levelling off, so D fits with that scenario.0764

The lac operon is a group of genes found in E. coli that are responsible for synthesizing0776

the enzymes that metabolize lactose sugar, that allow E. coli to break down lactose sugar.0783

The lac operon is turned off when a repressor protein is bound to it.0790

However, when lactose is present, the repressor is blocked from binding, so the repressor cannot0797

bind to the lac operon, and because the repressor is not bound, transcription can take place.0803

And this is a very well-studied set of genes, and the correct answer is A.0811

It is studied because it allows us to look at one model of the regulation of transcription.0818

Looking at answer B, that is scaling way up talking about what is going on in a mammal with utilization of lactose, E. coli or bacteria.0829

So, we are just looking at a very basic molecular mechanism when we study this.0840

RNA processing occurs after transcription.0845

The lac operon is studied to really see how transcription itself is regulated not necessarily processing that takes place after the transcript is created.0850

Cell cycle is related to cancer. However, this model, this lac operon is not really giving us insight into the cell cycle.0861

So, remember that this regulation of the cell cycle can cause out of control growth in cells, and that is one cause of cancer.0870

Question 8 provides you with an equation for photosynthesis.0884

And recall that in photosynthesis, carbon dioxide and water are used by plants to generate glucose using light energy.0889

Other product are water and oxygen, so those are other products of photosynthesis.0901

And we are asked to follow an atom and see where this atom is going to end up in the products.0908

The first three answers all are indicating an oxygen atom on water.0917

Now, in the light-dependent reaction...remember that there is light-dependent reactions and light-independent reactions in photosynthesis.0924

In the first set of reactions, the light-dependent reactions, water is split, so that process is called photolysis.0933

Recall the splitting of water using light. In this, water is split into two hydrogen ions plus one half of an O2 molecule.0942

Splitting water provides a source of electrons that are needed for the light-dependent reactions.0961

And what ends up happening when water is spit is that this one half O2 combines with another oxygen molecule to create O2 gas0968

which is released from the plant into the atmosphere, and the only one that is describing that is B.0978

B is indicating that the oxygen on water, on this twelve water molecules is oxygen as part of water will end up being released as oxygen gas.0986

A and C both show the oxygen on water, but they show it ending up...1000

In A, it ends up in the glucose, and in C, it ends up in water again. That is not correct.1007

D shows the oxygen from CO2 as being the source of oxygen released in the plant, which is not correct.1013

No. 9 is talking about transport across cell membranes and various molecules or mechanisms of transport.1030

So, we have to look at which one of these is correct.1041

The statement in A is inaccurate. Carbon is actually a symmetrical molecule that is non-polar, and it is non-polar because the electrons are equally shared.1043

And because it is a small non-polar molecule, it is permeable to the cell membrane. However, answer A is stating that carbon dioxide is polar.1055

B, starch is a large molecule, so it cannot diffuse across the cell membrane. C is the correct answer.1065

While water can diffuse across cell membranes also across many species of organisms, their cells contain aquaporins.1073

Or they are also called water channels to allow much more rapid uptake of water that the cell may need.1084

D is also inaccurate. Cristae are infoldings of the inner mitochondrial membrane.1094

And these infoldings actually increase the surface area of the inner mitochondrial membrane.1100

Protons can go through ATP synthase channels, so protons can pass through the cristae. However, oxygen does not.1107

So, the only accurate answer here is C which discusses the function of aquaporins or water channels.1115

Talking a little bit more about transport across cell membranes, recall that active transport requires the input of energy.1124

It transports molecules against their concentration gradients.1134

So, it requires energy transport protein, and it moves molecules against their concentration gradients.1142

So, a few things to think about as you are looking at these answers.1147

Glucose transport in A, glucose transport occurs by diffusion, and diffusion is a passive transport process. It does not require the input of energy.1154

Facilitated diffusion indicates that there is a carrier protein but facilitated diffusion is still a passive process1164

in which as this answer says, the molecules being moved down or along its concentration gradient.1175

The correct answer B discusses pumps. Protists have vacuoles to remove water, and these pumps do require energy.1181

That is a form of active transport, B.1193

Counter current exchange is actually a passive process. It is the passive diffusion of oxygen.1197

D is describing osmosis.1208

Remember that if you place a cell in a hypotonic solution, so a solution in which the solute concentration is1211

lower than the concentration of solutes inside the cell, water is going to rush in, and the cell will increase in volume.1221

And if that continues happening, the cell will eventually lyse or burst, but that again, this process is passive.1232

So, the only active transport described here is B, so 10, the answer is B.1240

Looking at structure of an animal cell. This is the cross section of a cell, and there are1250

four different structures pointed out and statements made about each of them.1257

Structure A is actually centrioles. That is a cross section of centrioles.1263

Centrioles are composed of microtubules. They are part of the spindle apparatus, and they allow the movement of chromosomes during cell division.1270

So, A is not correct. Centrioles do not function in detoxification, so that is not a correct answer.1284

Looking at what structure B is, structure B is a series of flattened sacs known as the golgi apparatus.1293

That is the correct answer. B is the Golgi apparatus, and the Golgi apparatus is the site of modification of protein and lipids.1302

And then, these proteins or lipids can be packaged for storage or for export from the cell, and B is actually describing that export process.1311

Looking at C, what structure is being described is the lysosome. Lysosomes contain hydrolytic enzymes, and the function is to break down old organelles,1324

macromolecule structures in the cell down to their just basic building blocks, component parts that can then be reused by the cell.1337

RNA synthesis does not take place inside lysosomes.1346

And then, finally, answer D is pointing out the endoplasmic reticulum. It is not part of the cytoskeleton.1352

The endoplasmic reticulum is an organelle that is a network of tubules and sacs.1359

Remember that there are two types of endoplasmic reticulum.1364

The rough endoplasmic reticulum has ribosomes attached to it, and it can synthesize proteins.1368

The smooth endoplasmic reticulum synthesizes lipids and steroid hormones, and the smooth endoplasmic reticulum in the liver is the site of detoxification.1376

So, actually A was talking about detoxification that would actually apply to the smooth ER.1387

Therefore, the only structure in the cell that is described correctly, that the function is described correctly is B.1393

Question 12 describes Cushing syndrome.1406

So, before we talk about Cushing syndrome, let's talk about how the pituitary gland normally affects the adrenal gland and the release of cortisol.1411

Let's talk about what is happening in a normal individual.1421

So, in a normal individual, the pituitary gland is going to release adrenocorticotrophic hormone, ACTH.1425

ACTH is then going to stimulate the adrenal glands which are located right by your kidneys to release cortisol.1434

Individuals with Cushing syndrome have a high level of cortisol release, and that causes a variety of symptoms.1448

There is a test used called the dexamethasone suppression test that is being described here.1456

And it allows physicians to figure out if the cause of this over secretion of cortisol is due to a1463

problem with the pituitary over producing ACTH or a problem with the adrenal glands directly.1470

Let's look at what happens in a normal patient here. In the normal patient there is a level of cortisol on the blood, normal level.1477

They do not give what that level is, but it just shows the baseline.1486

When dexamethasone is given in a normal patient, you will see decreased levels of cortisol in the blood.1490

Now, one action of dexamethasone is actually to block ACTH.1498

So, if dexamethasone is given and ACTH is blocked then, the adrenal glands will not be stimulated, and cortisol levels will decrease.1506

That is what you would expect to happen in a normal patient, and that is what does happen.1520

Now, let's look at this patient with Cushing syndrome.1525

They have a very high level of cortisol at baseline, and when dexamethasone is given, that level remains high.1527

And what that shows is that the issue is not at the level of the pituitary. The problem is the adrenal glands.1534

The adrenal glands are not under the normal control of ACTH. So, even when ACTH is blocked, they just keep secreting cortisol.1540

So, the problem is with the adrenal glands, and that aligns with answer C, which discusses the problem1548

in this particular patient, the cause of Cushing syndrome being the adrenal.1563

Even though ACTH is being blocked, adrenals are still producing high levels of cortisol.1567

Question 13 talks about the conversion of malate to oxaloacetate and gives various statements about it, and you are trying to find a true statement.1583

So, an allosteric enzyme changes its shape after it binds to an effector molecule.1598

But from the information given, we cannot determine whether this malate dehydrogenase is an allosteric enzyme or not.1604

Looking at B, that is a correct statement.1615

This is an exergonic reaction. This is a reaction that actually releases energy.1618

C is inaccurate. Remember that oxidation is the loss of electrons, whereas reduction is the gain of electrons.1625

And what you are seeing in this overall reaction is actually an oxidation reaction, the loss of the electrons with the removal of the hydrogen atoms.1642

D is also an inaccurate statement. It is stating that NAD+ is oxidized into NADH but actually NAD+ is reduced to NADH.1651

So, the only true statement here is that what you are seeing is an exergonic reaction.1663

Thinking about DNA in a particular cell type here and looking at which statement is accurate, and this is a fairly straightforward question.1672

The correct answer is A.1686

All cells in a particular individual, skin cells, liver cells, neurons all contain the same DNA.1692

However, different genes are expressed in different cell types, so depending on the function of the cell, particular genes will be expressed.1699

They will be transcribed and proteins will be made, but that same basic genetic material is in every cell, so the correct answer for 14 is A.1709

15, this is a fairly long question if you just break down each part, and it is talking about the topic of epistasis.1725

And what epistasis refers to is one set of genes affecting phenotype that results from another set of genes.1737

You can think of this as one set of genes modifying the effect of another set of genes.1752

And it really is most easily understood through an example, and this is a really great example here, and it is coat color in Labradors.1760

So, there are two sets of genes that you need to look at here, and the first one is for the amount of melanin present.1767

And the gene that controls that has two different alleles:1775

big B which is dominant, and that codes for black fur and then, the recessive allele which codes for brown hair.1780

However, there is a second set of genes. So, this is for melanin deposition.1791

Excuse me, how much melanin is present, the amount of melanin present. That is the set of genes.1800

Now, there is a second set of genes that is epistatic to this first set.1805

So, it actually exerts an effect that will influence the phenotype, and this set of genes influences pigment deposition.1810

If big E is not present, coat color will be yellow, so no big, no dominant allele for E equals yellow.1832

Looking at the various combinations that you are given, if an animal has this combination, big B big B, big E little E...let's look at each set here.1849

Big B big B is going to code for black coat color, and since big E is present, that is expressed.1865

So, I would expect this animal to have black coat color.1876

Now, answer A states that this combination gives brown coat color, so that is incorrect.1881

Looking at the next genotype given, big B big B, so heterozygous for both loci.1889

Because black is dominant to brown, the phenotype that I would expect is black, and since big E is present, that phenotype can be expressed.1901

So, I would expect color to be black. Therefore, B is incorrect.1914

C, here, again, heterozygous for melanin production, and seeing that big B there, I would say OK dominant, coat color is going to be black.1921

However, notice that there is no big E present, and remember, if there is no big E present,1935

it does not matter what is going on over here with the big B little B that coat color is going to be yellow.1943

So, this third combination, the coat color should be yellow.1950

So, the first three are incorrect. They are all giving incorrect phenotypes for the given genotype.1952

The correct answer is D. In D, what you see is big B big B which I would expect to produce a black coat color except there is no big E present.1957

So, again, if you see little E little E, coat color is yellow, and that is what the answer says, and that is the correct statement. 15 is D.1970

16, with 16, the important thing is to keep transcription and translation straight.1983

So, remember that going from DNA to RNA is the process of transcription.1994

When mRNA is used as a template for the production of protein, what you are talking about is translation.2009

And what this question is asking about is protein synthesis using an mRNA molecule, so it is talking about translation.2021

Answer A is talking about the suppression of expression of genes. That is transcription.2033

Again, here, the question is asking about translation, so A is not correct.2039

B, again, talking about transcription factors and things...well, it mentioned...2046

Actually this answer, it is pragmatic on various levels because it is talking about initiation of transcription which is going to produce RNA.2060

And then, it is saying that, that is going to determine the protein.2069

But they are actually talking about if you have a particular mRNA molecule, what is going to happen.2075

And the accurate answer is C because if messenger RNA is more quickly broken down,2082

there will be less opportunity for ribosomes to translate that RNA into protein.2094

D says that there is just one factor here. Ribosomes are the sole factor influencing the production of protein which is not correct.2106

So, the correct answer is C.2114

If you are looking at a particular mRNA molecule, one factor that affects the amount2115

of protein you get out of it is how quickly that messenger RNA is degraded.2120

17 shows a couple different hemoglobin oxygen saturation curves.2136

And looking at the graph and thinking about your background knowledge of this topic, which one of these is true?2146

The first answer compares the affinity of hemoglobin B for oxygen with that of hemoglobin A, and it is saying that it has a greater affinity.2155

Now, let's check that out on the graph.2164

If I look at a particular PO2, I am going to look at 60. At a PO2 of 60, the curve showing A shows that hemoglobin is about 90.2166

The saturation is 90. The oxygen saturation is 90.2179

Now, If I look at B at that same PO2 of 60, so looking at PO2 of 60, hemoglobin A, the O2 sat is about 90.2183

Now, if I look at that same PO2 of 60, hemoglobin B, the O2 saturation is only about 80.2199

What that suggests is that the affinity for hemoglobin B is actually lower than for hemoglobin A.2209

That is the opposite of what answer A is saying, so answer A is incorrect.2218

B cannot be concluded from this either.2224

If an animal has evolved in a very high oxygen level, it does not need to have such a high affinity for oxygen actually.2226

If an organism in a situation where oxygen is scarce, then, it needs to have hemoglobin2236

that really is sufficient at binding and grabbing onto the oxygen that is there.2242

If anything, I would actually think the opposite.2247

D, you cannot conclude that from this graph.2250

The correct answer is C. So, let's think out the rationale for this.2256

Now, looking at pH, the curve for A shows a pH of 7.4, and then, the curve for B is showing a more acidic environment.2262

Hemoglobin B, it is showing a pH of 7.2, so this is a more acidic environment.2279

And I already mentioned that hemoglobin B has a lower affinity for oxygen. This actually makes a lot of sense.2290

So, again C is the correct answer.2301

And the idea is that you need to think about wearing your body that would be in a slightly more acidic environment.2303

In tissues and in cells that are very active, that are metabolically active, like a muscle cell when you are exercising,2311

they are going to need a lot of energy, be very metabolically active, and as a product of that, they are going to produce CO2.2323

When CO2 combines with water, it produces carbonic acid.2335

Therefore, in regions where cells, tissues are using a lot of oxygen, the environment becomes more acidic.2340

So, what the body wants to do is have the hemoglobin carrying the oxygen travel to those2350

areas of the body and release, let go, deliver the hemoglobin to those areas.2358

So, when hemoglobin is in an environment that is acidic, where the oxygen is needed, you are going to want2364

the hemoglobin to have a lower affinity so it releases it, and that is exactly what you see with curve B, so again, answer C is correct.2371

18: triploid means that there are three sets of chromosomes, and it is true that bananas plants are triploid. They are sterile.2385

And the rationale for this is that during meiosis, homologous pairs of chromosomes line up at the metaphase plate.2396

However, there cannot be correct pairing of these chromosomes if there are three sets instead of two. Therefore, answer A is correct.2409

Just pointing out something with answer C, answer C is talking about mitosis. However, gametes are produced through the process of meiosis.2422

Looking at metabolic rate per gram of body weight versus mass and looking at various animals,2438

what statement here among these four answers is correct?2449

Well, A is incorrect because if it was a direct relationship then, what would I expect is that animals with larger2454

mass would actually have a higher metabolic rate per gram of body weight, and I am seeing the opposite here.2462

Large animals like a horse or an elephant actually have lower metabolic rates, so A is not correct.2471

B is again stating that this is a direct relationship which is not true.2479

And then, it goes on to talk about that an animal with a larger body mass would have a lower respiratory rate and a higher BMR.2484

And it is not fully giving an accurate description here.2499

I mean, the main issue is that as an animal gets larger, its metabolic rate actually gets lower.2503

So, while a lower metabolic rate would translate to a lower breathing rate, it would not translate to a higher BMR.2510

C is correct. Instead of a direct relationship, the relationship we see here is that metabolic rate, BMR and body mass are inversely proportional.2520

So, as body size increases, metabolic rate decreases. Very large animal like an elephant has a low BMR.2530

D is inaccurate. Larger animals have lower metabolic rates.2541

They have lower heart rates and lower respiratory rates than very small animals2548

like mice and rabbits that have high BMR, higher respiratory rate and higher heart rate.2552

Another graph and this one dealing with the immune system's response to antigens.2567

And on first exposure to an antigen, the body will produce a response.2576

And to get to the peak of the response as this graph is showing, it takes a couple weeks.2583

However, if the body sees that it is exposed to the antigen a second time, the response is much quicker and much stronger.2589

And thinking of this in real world terms, let’s say someone who has not been vaccinated for chicken pox is exposed to chicken pox.2597

The first time their body sees that virus, they are going to mount.2606

It is going to take some time, couple of weeks, and they are going to mount in a new response, and it is going to kind of lower.2612

If they are later on in life exposed to chicken pox again, they are going to have a very immediate strong response and be able to fight that off.2617

Now, what happens with this second antigen here?2625

Again, analogous to this real world example, if the person who had chicken pox is also then exposed to influenza virus,2630

the fact that they have been exposed to chicken pox is not going to affect their body's response to influenza virus.2641

And that is because the antibody response is part of the specific immune system, so it is specific to the antigen.2647

Memory cells that have been activated by a particular and recruited by a particular antigen will remain in the body.2657

And then, if that antigen comes back again, there is a re-exposure, these memory cells are ready to go but only for that particular antigen.2664

So, immunity or exposure to chicken pox is not going to help you fight off another type of virus. That situation is accurately depicted by B.2674

What B shows is that exposure to antigen A elicits an initial immune response, and then, a second exposure elicits a quicker, larger immune response.2688

The first exposure, the primary exposure to antigen B has a similar curve to the primary exposure to antigen A2702

in terms of the response, that there will be a response, but it is going to be relatively small and take a little longer to occur.2711

These other, like A and C is showing that antibody B would be rapidly produced in large amounts upon initial exposure which is not correct.2723

This is a first exposure to antigen B.2734

And then, for some reason in D, that individual is not producing antibodies to B despite exposure2738

which there is no explanation for that in this case, so the correct answer is B.2747

This question eludes back to epistasis which we discussed in question 15.2760

So, it discusses actually two different things: incomplete dominance and epistasis.2767

So, recall that in question 15, we talked about coat color of Labs, and that is controlled by two sets of genes.2773

And those two sets of genes were big B little B, and they had to do with melanin production and big E little E which had to do with pigment deposition.2784

And the presence of big E is required in order for the big B little B genes to be expressed.2795

So, this second set of genes is exerting an effect on this first set in terms of their expression. That is epistasis.2805

Incomplete dominance is a little bit different. Before we talk about incomplete dominance, let's talk about complete dominance.2814

With complete dominance, a good example is Mendel's pea plants, and one of the traits that he studied is height.2824

And the gene for height has two alleles: big T dominant for tall and little T for short or dwarf plants.2832

Big T, tall, is completely dominant to little T, so if you have a plant that is homozygous dominant, it is going to be tall, the phenotype will be tall.2844

If the genotype is heterozygous, the plant will also be tall.2855

You are not going to end up with a medium plant because big T is completely dominant over the little T, short phenotype.2860

Little T little T, the phenotype will be short. This is complete dominance.2871

Now, let's look at incomplete dominance.2878

The example here is with flower color in snapdragons, and the gene for this has two alleles. We are going to call them big R and little R.2890

Big R codes for red flower color. Little R codes for white flower color, so let's go through and see what happens.2906

If the plant is homozygous dominant, the plant is red. That is what I would expect.2915

If the plant is homozygous recessive, I would expect a white plant, and that is what I see.2922

Something interesting happens with the heterozygote, so big R and little R, these plants are actually pink.2928

Now, if there was complete dominance of big R over little R, big R would completely mask the expression of little R.2935

And I would expect the plant to be red, but the dominance of big R over little R is incomplete so the plant is pink.2942

So, now, after that discussion of epistasis versus incomplete dominance, let's go ahead and look at this question no. 21.2952

And D describes what I just discussed, that with incomplete dominance, you are just looking at two different alleles for a single gene.2961

Whereas with epistasis, there are multiple sets of genes, and one can exert an effect on the other. Therefore, the correct answer is D.2975

22 talks about why there was this surprising finding, that scientists expected to find many more genes2995

in the human genome than they actually discovered when they sequence the genome, so what would explain this?3006

There is so many traits in a human being controlled by relatively few genes. This is more just factual knowledge-based type question.3012

And first of all A is inaccurate. When histones are modified, what we usually see is actually a decrease in the function of proteins, so that is incorrect.3026

Epigenetics is a very hot term right now, a very hot area of research.3036

Epigenetics means over or above genetics, so epigenetics over or above genetics.3042

And what this refers to is a change that can increase or decrease the expression of a gene, but it does not alter the DNA sequence.3054

One example of epigenetics is methylation. So, methylation of DNA can supress the expression of genes.3066

And epigenetics refers to changes that are not in the DNA sequence itself, but they are heritable.3074

And these factors can also be influenced by environment.3083

So, anyways, that is the description of epigenetics, but B is not an accurate statement about epigenetics.3087

Pseudogenes are closely related to genes, but they do not lead to the production of a protein. Introns are not expressed either.3094

That is inaccurate. D is correct.3103

Remember that you have got a DNA sequence, and there will be exons, parts of the DNA that code for gene.3107

And then, there are these introns. You can think of them as just sequences that just interrupt the genes.3118

And so you have these various exons and introns.3127

And transcription occurs leading to the production of pre-mRNA, and pre-mRNA is going to contain the sequence for both the exons and the introns.3132

And remember that some modifications are going to occur in order...processing will occur to convert pre-mRNA to mRNA such as the addition of a poly-A tail.3147

Another type of processing that occurs is splicing, and there are alternative ways that this transcript can be spliced.3162

One way would be to splice it like this so that you will end up with mRNA like this. However, there is another possibility.3171

Instead of splicing it like this, let's look at the same pre-mRNA and splice it a little bit differently so that this exon is removed.3188

As you can see then with the sequence, you can get different combinations through alternative splicing or differential splicing as it sometimes called.3205

Therefore, the correct answer for 22 is D.3216

23: so we are back to talking about photosynthesis and in particular, the light-dependent reactions.3224

Remember that in the light-dependent reactions, photolysis occurs, and that is the splitting of water. That is what is described in C.3231

So, overall in the light-dependent reactions, light energy is used to produce ATP.3243

As a part of this, you need a source of electrons, and water provides that source, so water is split to provide a source of electrons.3250

The other response is here referred to the light-independent processes.3258

For example A is talking about CO2 being used as a source of carbon to produce glucose.3265

Again, that happens in the second part of photosynthesis, the light-independent reactions.3273

However, remember that the light-independent reactions actually require ATP that is produced from the light-dependent reactions.3279

OK, B also describing the production of a product from the light-independent reactions.3288

And then, D, the light-independent reactions take place in the stroma. The light-dependent reactions take place in the grana, OK.3297

So, C is the only one that refers to light-dependent reactions.3308

The acrosome is found at the head of the sperm, and it releases enzymes that allow a sperm to penetrate an ovum so that fertilization can occur.3317

Now, immediately upon fertilization, cortical granules are released from the ovum.3329

And these granules actually help to form a barrier around the egg so that additional sperm cannot fertilized that egg.3336

So, what is being described here with these reactions is actually C, preventing multiple sperm from fertilizing a single egg- C.3345

25 is a very broad question. Actually, the only response here that fits is A.3359

All cells are surrounded by a cell membrane or plasma membrane that separates the cell from its surrounding environment.3371

Not all cells have a nucleus. Remember that prokaryotic cells do not contain membrane-bound organelles.3379

They do not contain a nucleus, so B is not correct.3390

Again, mitochondria, that is a membrane-bound organelle, not every cell has that.3394

And the surface to volume ratio of cells actually varies, so A is the correct response.3398

26 is talking about translation, and you are given a sequence of an mRNA and ask what would happen with a mutation occurred.3410

And you are given this table of the codons and what amino acids or what they code for.3418

Now, this refers to an alteration of bold phased A, but actually what they show here is that the mutation has already taken place.3429

So, it is showing the U which is presumably an A before, and now, post mutation is a U.3437

And if you look at the middle codon UAA, and you look at what it codes for3444

using that chart that you are given, you will see that UAA is a stop codon.3452

What this means is that when the ribosome encounters that sequence UAA, it is going to dissociate.3458

It is going to stop translation, and that polypeptide chain will be finished.3465

So, even though there are additional codons after that, those will not be translated.3470

So, this protein is going to be non-functional. This is a very serious kind of mutation, and the correct answer is C.3476

This next question talks about clear cutting, and looking at a negative consequence,3492

a bad outcome that could occur due to clear cutting in a tropical rain forest area.3501

One very negative consequence that they are discussing here is potentially less precipitation.3512

And that is because trees are an important part of the water cycle.3518

Recall that in the water cycle, water evaporates from bodies of water such as lakes, rivers and oceans, so it evaporates up into the atmosphere.3523

However, water also evaporates from trees, so it is taken up by the trees via the roots and then, evaporates in the process of transpiration.3535

So, that water that has evaporated from bodies of water or transpired back into3546

the atmosphere is actually carried higher up into the atmosphere by air currents.3550

Cooler temperatures higher up in the atmosphere cause that water vapor to form into clouds.3556

Eventually, precipitation occurs, and the water is released from the clouds.3561

It returns back to the ground, into the soil, into the bodies of water, so come full circle.3566

Clear cutting can disrupt the water cycle by eliminating trees and therefore, transpiration. Therefore, the correct answer is B.3574

OK, so, DDT is a pesticide, and we are supposed to figure out why some mosquitoes...3594

the mechanism by which an explanation for them becoming resistant to this pesticide.3606

So, initially, pesticide was used very, very effective, but eventually, populations of mosquitoes arose that did not die when they were exposed to DDT.3609

And the explanation for that is B. This is really just describing the process of natural selection,3619

that in any population whether it is mosquitoes or mice or elephants or humans, in any population there is a variety of traits.3627

So, some mosquitoes were resistant to DDT.3635

They carried a particular gene or set of genes that gave them a phenotype that made them resistant.3640

So, when DDT was sprayed, susceptible mosquitoes were killed by the DDT, and those mosquitoes carrying a trait that made them resistant survived.3647

And so that is the explanation for B.3659

Then, what would happen is the mosquitoes that survived would have offspring.3662

Then, they may pass on the genotype for resistance to DDT to their offspring.3667

And therefore, that trait increases in frequency in the population.3673

And eventually, the surviving mosquitoes, the majority of them would have that trait if they have had this selective pressure put upon the population.3677

So, again, the answer is B.3688

29: so, we are looking at humans and chimpanzees in terms of similarities in genetic sequences.3692

What would explain the fact that there are these many similar sequences between humans and chimpanzees.3707

An explanation would be C. If humans and chimpanzees diverged evolutionary relatively recently,3716

so they have a recent common ancestor, that could explain why they have so many similar sequences in their genomes.3724

Looking at D, if they were branched off 4 billion year ago from a distant common ancestor,3731

I would actually expect them to have relatively few sequences in common on their genome.3740

So, the correct answer for 29 is C.3746

30: You are given a description of a situation involving natural selection.3752

So, there was a drought, and therefore, there was less food, less seeds available to birds.3760

And the seeds that were available were large ones that were maybe harder for the birds with smaller beaks to eat.3768

So, what would happen is that those finches that happen to have larger beaks and could eat these3777

bigger tougher seeds were more likely to survive, and they were more likely to reproduce.3784

And when they reproduced, they passed on the genes for larger beak to their offspring.3792

And eventually, there were higher frequency of these larger beaked birds in the population.3798

And the average size of beaks within that population would increase when you went in and measured it after this drought, so D.3803

Again, we are just talking about natural selection here and how it can favor individual with the particular trait, here, beak size.3813

Those individuals survive. They reproduce, and then, that trait becomes more common in the population.3821

Really, I have also explained 31 at the same time because it is asking about what is behind this change, the mechanism for the change which is B.3828

The pressure exerted on the finch population favored larger beaks. It favored individuals carrying the genes for larger beaks.3839

Those genes were then passed on to their offspring. Birds that did not carry that trait were less likely to survive and reproduce.3848

So, the frequency of genes for a large beak size increased in the population.3856

That concludes this lesson for Educator.com. Thank you for visiting.3864

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