ap biology

1. Properties of Water:

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Polarity: Uneven charge distribution (Oxygen = slightly negative, Hydrogens = slightly

positive)

Hydrogen bonding: Weak bonds between water molecules

Cohesion: Water sticks to itself (beads up)

Adhesion: Water sticks to other surfaces (capillary action)

High Specific Heat: Resists temperature changes (important for stable environments)

Ice Floats: Solid water is less dense than liquid — life survives under ice!

2. Macromolecules of Life:

Macromolecule Monomer Key Function Example

Carbohydrate Monosaccharide Energy & Structure Glucose, Starch

Protein Amino Acid Enzymes, Structure Hemoglobin, Keratin

Lipid Glycerol + Fatty

Acids

Membranes, Energy

Storage

Phospholipid Bilayer,

Fats

Nucleic Acid Nucleotide Genetic Information DNA, RNA

3. Protein Structure Levels:

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Primary: Sequence of amino acids

Secondary: Alpha helices, beta sheets

Tertiary: 3D folding (functional shape)

Quaternary: Multiple proteins interacting (ex: hemoglobin)

🧠 Must-Know Vocabulary:

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Hydrogen bond

Cohesion/Adhesion

Dehydration synthesis (building polymers)

Hydrolysis (breaking polymers)

Monomer, polymer

Hydrophilic vs. Hydrophobic

✏ Mini Self-Check Quiz:

✅ 1. What type of bond connects water molecules?

✅ 2. What are the monomers of proteins?

✅ 3. Why does ice float?

(Answers at the back of the review.)

📈 Diagram Suggestion:

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Draw water molecules (Mickey Mouse shape: two small hydrogens, one big oxygen)

Show hydrogen bonds between molecules

Label partial charges (+/-)

🧠

"The important thing is to not stop questioning. Curiosity has its own

reason for existing.

"

— Albert Einstein

4🧬 UNIT 2: Cell Structure and Function

✨ Big Ideas:

Cells are like microscopic cities — each organelle is a specialized building or department.

The cell membrane is a security gate (semi-permeable), controlling who gets in or out.

Eukaryotic cells (animals, plants) have membrane-bound organelles.

Prokaryotic cells (bacteria) are simpler — no organelles, no nucleus.

🧪 Essential Concepts:

1. Types of Cells:

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Prokaryotic Cells: No nucleus, no membrane-bound organelles, DNA floats in nucleoid

(ex: bacteria, archaea)

Eukaryotic Cells: True nucleus, many organelles (ex: plants, animals, fungi, protists)

2. Important Organelles and Their Functions:

Organelle Function Analogy

Nucleus Stores DNA City Hall

Ribosomes Make proteins Factories

Rough ER Modifies proteins (has ribosomes) Highway with factories

Smooth ER Makes lipids, detoxifies Oil refinery

Golgi Apparatus Packages proteins for export Post office

Mitochondria Produces ATP (energy) Power plant

Chloroplasts Photosynthesis (plants only) Solar panels

Lysosomes Break down waste Recycling center

Vacuoles Storage (water, food) Storage warehouse

Cytoskeleton Structural support, movement City roads & bridges

53. Membranes and Transport:

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Phospholipid Bilayer: "Heads" are hydrophilic,

"tails" are hydrophobic → forms

semi-permeable barrier.

Selective Permeability: Only certain substances (like small nonpolar molecules) pass

easily.

Transport Types:

○

Passive Transport: No energy (diffusion, osmosis)

○

Active Transport: Requires energy (pumps like Na⁺/K⁺ pump)

○

Facilitated Diffusion: Passive transport through proteins

🧠 Must-Know Vocabulary:

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Organelle

Prokaryote vs. Eukaryote

Phospholipid bilayer

Diffusion

Osmosis

Active vs Passive Transport

Surface Area to Volume Ratio (SA:V)

📈 Special Topic: Surface Area-to-Volume Ratio

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As a cell grows, its volume increases faster than its surface area.

Smaller cells are more efficient at exchanging materials with their environment.

That's why cells stay small — to avoid starvation or waste buildup!

✏ Mini Self-Check Quiz:

✅ 1. What organelle is responsible for making ATP?

✅ 2. How do materials move across a membrane without using energy?

✅ 3. Why are cells so small?

(Answers at the back of the review.)

6📈 Diagram Suggestion:

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Draw a basic animal cell and plant cell.

Label key organelles: nucleus, mitochondria, ribosomes, ER, Golgi, vacuole,

chloroplasts (plant).

🌟 "Nothing in life is to be feared. It is only to be understood.

"

— Marie Curie

7⚡ UNIT 3: Cellular Energetics

✨ Big Ideas:

Cells need energy to survive — and they have evolved amazing biological machines

(enzymes, mitochondria, chloroplasts) to manage energy transformations efficiently.

Energy flows like money in a city: it's earned (photosynthesis), spent (cellular respiration), and

constantly recycled through metabolism.

🧪 Essential Concepts:

1. Enzymes — Biological Catalysts:

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Enzymes speed up reactions by lowering activation energy.

Specificity: Each enzyme only fits a particular substrate ("lock-and-key" model or

"induced fit" model).

Active site: The part of the enzyme where the substrate binds.

Environmental factors: pH, temperature, and substrate concentration can affect

enzyme activity.

Enzyme Behavior:

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Too hot → enzymes denature (lose shape = no function).

Optimal conditions → maximum efficiency.

Competitive inhibitors → block the active site.

Noncompetitive inhibitors → bind elsewhere, change the enzyme’s shape.

2. Photosynthesis (Plants and Algae):

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Location: Chloroplasts

Purpose: Capture light energy → store it as chemical energy (glucose)

Equation:

6 CO₂ + 6 H₂O + light energy → C₆H₁₂O₆ + 6 O₂

Two Major Steps:

8Step Location Main Idea

Light-dependent reactions Thylakoid

membranes

Light-independent reactions (Calvin

Stroma Cycle)

Capture sunlight, make ATP and

NADPH

Use ATP and NADPH to build

glucose

3. Cellular Respiration (All Eukaryotes):

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Location: Mitochondria

Purpose: Break down glucose → release energy (ATP)

Equation:

C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + ATP (energy)

Three Major Steps:

Step Location Main Idea

Glycolysis Cytoplasm Glucose → 2 pyruvate + small

Krebs Cycle (Citric Acid

Cycle)

Electron Transport Chain

(ETC)

Mitochondrial Matrix ATP

Makes electron carriers (NADH,

FADH₂)

Inner mitochondrial

membrane

Uses oxygen → lots of ATP made

Oxygen is essential at the end of the ETC as the final electron acceptor!

(No oxygen? Fermentation happens instead — less ATP.)

🧠 Must-Know Vocabulary:

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Enzyme

Activation Energy

Substrate

Denaturation

Photosynthesis

Light reactions

Calvin Cycle

Glycolysis

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Krebs Cycle

Electron Transport Chain (ETC)

ATP

📈 Special Topic: Energy Coupling

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Cells use ATP hydrolysis (breaking ATP → ADP + P) to drive endergonic

(energy-requiring) reactions.

Think of ATP as the universal rechargeable battery of the cell.

✏ Mini Self-Check Quiz:

✅ 1. What organelle is responsible for cellular respiration?

✅ 2. Where do the light-dependent reactions occur?

✅ 3. What molecule is the final electron acceptor in the Electron Transport Chain?

(Answers at the back of the review.)

📈 Diagram Suggestion:

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Draw a mitochondrion and label the Matrix, Inner Membrane, and show ETC happening.

Draw a chloroplast and show thylakoids (light reactions) and stroma (Calvin Cycle).

🔥 "Energy is liberated matter, matter is energy waiting to happen.

"

— Bill Bryson (paraphrasing physics)

10🔔 UNIT 4: Cell Communication and Cell

Cycle

✨ Big Ideas:

Cells aren't isolated — they talk to each other using chemical signals to coordinate life

processes like growth, defense, and reproduction.

The Cell Cycle controls when cells grow and divide.

When communication or cycle control fails → cancer can happen.

🧪 Essential Concepts:

1. Cell Communication Overview:

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Signal transduction: Sending a signal through a series of molecular steps inside the

cell.

Three basic stages of cell signaling:

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Reception: Cell detects a signal molecule (ligand) using a receptor.

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Transduction: Relay molecules pass the message inside the cell.

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Response: The cell changes behavior (gene activation, enzyme action, etc.)

2. Types of Signaling Between Cells:

Type Description Example

Autocrine Cell signals itself Paracrine Cell signals nearby cells Immune cells activating themselves

Neurotransmitters between neurons

Endocrine Long-distance signaling via hormones Insulin regulating blood sugar

Key point:

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Specificity matters — only cells with the right receptors can "hear" the signal.

113. Key Players:

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Ligand: The signaling molecule (like a key)

Receptor Protein: On cell membrane or inside cell (like a lock)

Second Messengers: Small molecules inside the cell that amplify signals (ex: cAMP,

calcium ions)

Kinase Cascade: A series of protein activations (phosphorylation events) —

"domino

effect.

"

4. The Cell Cycle:

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Purpose: Cell growth and division.

Phases:

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G₁ Phase: Cell grows

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S Phase: DNA replicates

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G₂ Phase: Prepares for division

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M Phase (Mitosis): Nucleus divides, followed by cytokinesis (splitting of

cytoplasm)

Checkpoints are critical:

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G₁ checkpoint: Decides if cell will divide

G₂ checkpoint: Checks DNA replication

M checkpoint: Ensures chromosomes align correctly before separation

5. Mitosis — The Steps:

Phase What Happens

Prophase Chromosomes condense, spindle fibers form

Metaphase Chromosomes align at cell center

Anaphase Sister chromatids separate

Telophase New nuclear membranes form

Cytokinesis Cytoplasm divides

🧠 Must-Know Vocabulary:

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Ligand

Receptor

Signal transduction

Second messenger

Kinase

Cell cycle phases (G₁, S, G₂, M)

Checkpoints

Mitosis (PMAT)

Cancer (uncontrolled cell growth)

📈 Special Topic: Cancer and Checkpoints

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Cancer cells ignore checkpoints.

Mutations in genes like p53 (guardian of the genome) can cause unchecked cell division

→ tumors.

✏ Mini Self-Check Quiz:

✅ 1. What is the second step in signal transduction?

✅ 2. During which mitotic phase do chromosomes line up in the middle?

✅ 3. Name a protein that can stop the cell cycle if DNA is damaged.

(Answers at the back of the review.)

📈 Diagram Suggestion:

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Draw a basic signal transduction pathway: receptor → second messenger → cellular

response.

Sketch the four stages of mitosis (PMAT).

🧠

"Life is like riding a bicycle. To keep your balance, you must keep

moving.

"

— Albert Einstein

13🧬 UNIT 5: Heredity

✨ Big Ideas:

Genetics explains how traits are passed from one generation to the next.

It’s like shuffling a deck of cards — each offspring gets a random combination of genes from

their parents.

Mendel figured out the basic rules of inheritance by breeding pea plants — and the principles he

discovered still apply today!

🧪 Essential Concepts:

1. DNA, Genes, and Chromosomes:

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Gene: Segment of DNA that codes for a trait.

Chromosome: Long DNA molecule with many genes.

Allele: Different versions of a gene (ex: blue eyes vs. brown eyes).

Each individual inherits two alleles for each gene — one from mom, one from dad.

2. Mendel’s Laws:

Law of Segregation Law of Independent

Assortment

Law Description

Two alleles for a gene separate during gamete formation

(meiosis)

Genes for different traits are inherited independently if they're on

different chromosomes

3. Key Vocabulary:

Term Definition

Homozygous Two identical alleles (AA or aa)

14Heterozygous Two different alleles (Aa)

Genotype Phenotype Dominant Recessive The genetic makeup (AA, Aa, or aa)

The physical trait expressed (purple flowers, tall plants)

Trait that shows when at least one allele is present

Trait that only shows when both alleles are recessive

4. Punnett Squares:

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Predict the probabilities of offspring genotypes and phenotypes.

Simple cross example:

Aa × Aa → 1 AA : 2 Aa : 1 aa (genotypic ratio)

5. More Complex Inheritance Patterns:

Pattern Description Example

Incomplete Dominance Blending of traits Red + white flowers →

pink

Codominance Both traits fully show AB blood type

Multiple Alleles More than two possible alleles Blood types: A, B, O

Sex-linked Traits Genes on sex chromosomes (usually

X)

Color blindness,

hemophilia

6. Meiosis — Foundation of Heredity:

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Creates gametes (sperm, egg) with half the normal number of chromosomes.

Crossing over (prophase I) creates genetic variation.

Independent assortment randomizes which chromosome copy ends up in each

gamete.

🧠 Must-Know Vocabulary:

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Allele

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Homozygous / Heterozygous

Genotype / Phenotype

Dominant / Recessive

Punnett square

Incomplete dominance

Codominance

Sex-linked trait

Meiosis

Crossing over

📈 Special Topic: Pedigrees

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Family trees showing inheritance of traits.

Circles = females, squares = males

Shaded = shows the trait

Analyze whether traits are dominant, recessive, or sex-linked based on patterns.

✏ Mini Self-Check Quiz:

✅ 1. What’s the difference between genotype and phenotype?

✅ 2. What’s the expected phenotypic ratio of a monohybrid Aa × Aa cross?

✅ 3. In a pedigree, what does a shaded square represent?

(Answers at the back of the review.)

📈 Diagram Suggestion:

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Draw a basic Punnett square (Aa × Aa).

Sketch a simple pedigree chart (family tree for a trait).

🌱 "The genes hold culture on a leash. The leash is very long, but inevitably,

culture conforms to biology.

"

— E.O. Wilson

16🧬 UNIT 6: Gene Expression and

Regulation

✨ Big Ideas:

DNA isn’t just a static instruction manual — it’s dynamic.

Cells can turn genes on or off based on their needs, environment, and type.

This control is essential for specialization (brain cells vs. muscle cells) and response to external

signals.

🧪 Essential Concepts:

1. Central Dogma of Molecular Biology:

Step Description

DNA → RNA → Protein DNA is transcribed into RNA, then RNA is translated into proteins

Key Processes:

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Transcription: DNA → RNA (in nucleus)

Translation: RNA → Protein (in cytoplasm at ribosome)

2. Transcription (Making RNA):

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Initiation: RNA polymerase binds to promoter region.

Elongation: RNA polymerase reads DNA and builds single-stranded mRNA.

Termination: RNA polymerase stops at a termination signal.

RNA processing (Eukaryotes only):

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Add a 5' cap and poly-A tail to protect mRNA.

Splice out introns (noncoding regions), connect exons.

173. Translation (Making Protein):

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Occurs at ribosomes.

mRNA codons (triplets of nucleotides) match with tRNA anticodons.

Each tRNA carries an amino acid → builds a polypeptide chain.

Start codon: AUG (Methionine)

Stop codons: UAA, UAG, UGA

4. Gene Regulation:

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Prokaryotes (like bacteria): Operons regulate gene expression efficiently.

Example: lac operon:

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Normally OFF.

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Turns ON in presence of lactose → makes proteins needed to digest lactose.

Part Role

Promoter Where RNA polymerase binds

Operator On/off switch controlled by repressor protein

Structural genes Code for enzymes

5. Eukaryotic Gene Regulation:

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More complex than prokaryotes.

Controlled by:

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Transcription factors

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Enhancers and silencers

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Epigenetic changes (like DNA methylation and histone modification)

Epigenetics = Changes to gene expression without changing DNA sequence!

6. Mutations:

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Point mutations: Single base changes (substitution)

Frameshift mutations: Insertion/deletion — shifts the reading frame → usually more

damaging.

18Type Example Effect

Silent Change codon, no change to amino acid No effect

Missense Change codon, changes amino acid Possibly harmful

Nonsense Change codon to stop codon Protein truncated

🧠 Must-Know Vocabulary:

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Transcription

Translation

RNA Polymerase

Promoter

Codon

Anticodon

Operon

Repressor

Enhancer

Epigenetics

Mutation (silent, missense, nonsense, frameshift)

📈 Special Topic: Viral Genetics

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Viruses hijack host cell machinery to reproduce.

Some viruses (like HIV) are retroviruses — they reverse-transcribe RNA into DNA.

✏ Mini Self-Check Quiz:

✅ 1. What enzyme is used during transcription?

✅ 2. What molecule matches mRNA codons during translation?

✅ 3. What’s the difference between a silent mutation and a nonsense mutation?

(Answers at the back of the review.)

19📈 Diagram Suggestion:

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Sketch the lac operon (Promoter → Operator → Genes layout).

Draw the Central Dogma flow: DNA → RNA → Protein.

🧬 "In nature, nothing is perfect and everything is perfect.

"

— Alice Walker

20🦎 UNIT 7: Natural Selection

✨ Big Ideas:

Life evolves.

Populations — not individuals — change over time through the process of natural selection,

driven by environmental pressures.

Evolution is like a never-ending survival tournament: traits that help an organism survive and

reproduce become more common generation after generation.

🧪 Essential Concepts:

1. Darwin’s Theory of Natural Selection:

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Variation: Individuals in a population differ in traits.

Overproduction: Organisms produce more offspring than can survive.

Adaptation: Some traits improve survival/reproduction.

Descent with Modification: Beneficial traits become more common over generations.

2. Fitness:

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Fitness = Ability to survive and reproduce.

Not necessarily the strongest or fastest — the best "fit" for the environment wins.

3. Sources of Genetic Variation:

Source Description

Mutation Changes in DNA (raw material for evolution)

Sexual reproduction New allele combinations

Gene flow Movement of alleles between populations (migration)

214. Types of Natural Selection:

Directional

selection

Stabilizing

selection

Disruptive

selection

Type Effect Example

One extreme phenotype

favored

Intermediate phenotype

favored

Both extremes favored Peppered moths during Industrial

Revolution

Human birth weight

Small and large beak sizes in finches

5. Evidence for Evolution:

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Fossil Record: Shows gradual changes over time.

Homologous Structures: Same structures → different functions (evidence of common

ancestry).

Vestigial Structures: Leftovers from ancestors (ex: human appendix).

Embryology: Similar development stages across species.

Molecular Biology: Similar DNA/RNA/proteins across species.

6. Hardy-Weinberg Equilibrium: Predicts how gene frequencies behave without evolution.

Equation for allele frequencies:

p + q = 1

Equation for genotype frequencies:

p² + 2pq + q² = 1

Symbol Meaning

p Frequency of dominant allele

q Frequency of recessive allele

p² Homozygous dominant genotype frequency

2pq Heterozygous genotype frequency

q² Homozygous recessive genotype frequency

22Conditions for Hardy-Weinberg (rare in real life!):

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Very large population

No mutations

No migration (gene flow)

Random mating

No natural selection

If any are violated → Evolution is happening!

🧠 Must-Know Vocabulary:

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Natural selection

Adaptation

Fitness

Mutation

Gene flow

Genetic drift

Hardy-Weinberg equilibrium

p and q (allele frequencies)

📈 Special Topic: Genetic Drift

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Random events (not natural selection) can change allele frequencies.

More dramatic in small populations.

Examples:

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Bottleneck effect: Disaster reduces population size.

Founder effect: Small group starts a new colony with different allele frequencies.

✏ Mini Self-Check Quiz:

✅ 1. In Hardy-Weinberg, what does p² represent?

✅ 2. Name one example of directional selection.

✅ 3. What is genetic drift?

(Answers at the back of the review.)

23📈 Diagram Suggestion:

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Sketch a basic Hardy-Weinberg triangle (p, q, p²

, 2pq, q²).

Draw graphs of different types of selection (directional, stabilizing, disruptive).

🌎 "It is not the strongest of the species that survives, nor the most

intelligent, but the one most responsive to change.

"

— Charles Darwin

24🌿 UNIT 8: Ecology

✨ Big Ideas:

Ecology is the study of how organisms interact with each other and their environment.

Life depends on energy flow (mostly from the sun) and cycling of nutrients through

ecosystems.

Organisms don’t live alone — they’re part of complex webs of life.

🧪 Essential Concepts:

1. Levels of Ecological Organization:

Level Definition

Organism One individual

Population Group of the same species

Community Different populations interacting

Ecosystem Community + abiotic factors

Biome Large region with similar climate and organisms

Biosphere All life on Earth

2. Energy Flow in Ecosystems:

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Producers (Autotrophs): Capture energy (ex: plants via photosynthesis)

Consumers (Heterotrophs): Eat others for energy

Decomposers: Break down dead material, recycle nutrients

Trophic Levels:

Level Example

1st Producer (plants)

252nd Primary consumer (herbivore)

3rd Secondary consumer (carnivore)

4th Tertiary consumer (top predator)

Only ~10% of energy is passed from one trophic level to the next — the rest is lost as heat

(Second Law of Thermodynamics).

3. Biogeochemical Cycles: Nutrients like carbon, nitrogen, and water cycle between living

organisms and the environment.

Cycle Important Processes

Carbon Cycle Photosynthesis, respiration, combustion

Nitrogen Cycle Nitrogen fixation, nitrification, denitrification

Water Cycle Evaporation, condensation, precipitation

4. Population Ecology:

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Carrying Capacity (K): Maximum population size the environment can sustain.

Exponential Growth: J-shaped curve (unlimited resources — unrealistic long term).

Logistic Growth: S-shaped curve — population stabilizes at carrying capacity.

Factors affecting population size:

Factor Type Examples

Density-dependent Competition, predation, disease

Density-independent Natural disasters, climate change

5. Species Interactions:

Type Description Example

Mutualism Both benefit Bees and flowers

Commensalism One benefits, other unaffected Barnacles on whales

26Parasitism One benefits, one harmed Ticks on dogs

Predation Predator kills prey Lion and zebra

Competition Species compete for resources Plants competing for sunlight

🧠 Must-Know Vocabulary:

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Autotroph

Heterotroph

Decomposer

Trophic levels

10% rule

Biogeochemical cycles

Carrying capacity

Logistic growth

Mutualism / Parasitism / Predation

📈 Special Topic: Ecological Succession

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Primary succession: Starts from bare rock (ex: after a volcanic eruption).

Secondary succession: Restores an existing ecosystem (ex: after a forest fire).

Pioneer species like lichens and mosses start the rebuilding process!

✏ Mini Self-Check Quiz:

✅ 1. What percentage of energy is passed between trophic levels?

✅ 2. What’s an example of a mutualistic relationship?

✅ 3. What is carrying capacity?

(Answers at the back of the review.)

📈 Diagram Suggestion:

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Draw a simple energy pyramid (Producers → Primary Consumers → Secondary →

Tertiary).

Sketch the water cycle (evaporation → condensation → precipitation).

🌎 "The Earth is what we all have in common.

"

— Wendell Berry

28➗ AP Biology Math Skills Review

✨ Big Ideas:

AP Biology expects you to interpret data, run basic calculations, and

apply simple statistical analysis — no calculators needed!

Math helps you make predictions, analyze experiments, and prove

biological theories.

🧪 Essential Concepts:

1. Chi-Square (χ²) Tests —

difference due to chance?"

"Is the

Purpose:

●

Formula:

χ² = Σ[(o – e)² ÷ e]

To determine if observed results are significantly different from expected results.

Symbol Meaning

o observed value

e expected value

Steps:

1. 2. Calculate (o – e)² ÷ e for each category.

Add them up → χ² value.

293. Compare to the critical value (based on degrees of freedom = number of categories –

1).

4. If χ² > critical value → reject the null hypothesis (results are not due to chance).

Common critical value at p = 0.05 → you can usually assume significance if χ² exceeds the

critical value for that degree of freedom.

2. Hardy-Weinberg Equilibrium —

are alleles behaving?"

Purpose:

●

To predict genotype frequencies if a population is not evolving.

Key Equations:

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p + q = 1 (allele frequencies)

p² + 2pq + q² = 1 (genotype frequencies)

"How

Symbol Meaning

p frequency of dominant allele

q frequency of recessive allele

p² frequency of homozygous dominant individuals

2pq frequency of heterozygous individuals

q² frequency of homozygous recessive individuals

Example Problem:

If 9% of a population is homozygous recessive (q² = 0.09), what is q?

q = √0.09 = 0.3

Then p = 0.7 (because p + q = 1)

You can then solve for all genotype frequencies!

303. Rate Calculations —

"How fast is

something happening?"

Enzyme Reactions, Population Growth, Photosynthesis Rates

Formula:

Rate = (Change in amount) ÷ (Change in time)

Example:

If oxygen produced goes from 2 mL to 8 mL in 5 minutes:

Rate = (8 - 2) ÷ 5 = 6 ÷ 5 = 1.2 mL/minute

4. Graph Interpretation —

story?"

You must be able to:

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Identify independent variables (plotted on x-axis).

Identify dependent variables (plotted on y-axis).

Recognize trends (increase, decrease, stable).

Estimate values between points (interpolation).

Predict values outside the graph (extrapolation).

Best practices:

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Always label axes with units.

Look for plateaus, sudden spikes, or thresholds.

"What’s the

5. Percent Change —

or smaller?"

"How much bigger

Formula:

% Change = [(Final – Initial) ÷ Initial] × 100

31Example:

Start with 50 plants, end with 75 plants:

[(75 – 50) ÷ 50] × 100 = (25 ÷ 50) × 100 = 0.5 × 100 = 50% increase

🧠 Must-Know Math Vocabulary:

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Chi-square (χ²)

Null hypothesis

Degrees of freedom

Allele frequency (p, q)

Genotype frequency (p²

, 2pq, q²)

Rate

Independent variable

Dependent variable

Percent change

✏ Mini Self-Check Quiz:

✅ 1. If q² = 0.04, what is q? What is p?

✅ 2. If observed data matches expected exactly, what would χ² be?

✅ 3. On a graph of enzyme activity vs temperature, which is the independent variable?

(Answers at the back of the review.)

32✅ Mini Self-Check Quiz Answers

Unit 1: Chemistry of Life

1. 2. 3. Hydrogen bonds connect water molecules.

Amino acids are the monomers of proteins.

Ice floats because solid water is less dense than liquid water (due to hydrogen bond

structure).

Unit 2: Cell Structure and Function

1. Mitochondria make ATP.

2. 3. By passive transport (simple diffusion or facilitated diffusion).

Cells are small to maintain a high surface area-to-volume ratio for efficient exchange.

Unit 3: Cellular Energetics

1. 2. 3. Mitochondria carry out cellular respiration.

Light-dependent reactions occur in the thylakoid membranes.

Oxygen is the final electron acceptor in the Electron Transport Chain.

Unit 4: Cell Communication and Cell Cycle

1. 2. 3. Transduction is the second step in signaling.

Chromosomes align at the center during metaphase.

p53 is a key protein that halts the cell cycle if DNA is damaged.

Unit 5: Heredity

1. 2. Genotype = genetic makeup; Phenotype = physical expression.

3:1 phenotypic ratio (dominant to recessive).

333. A shaded square in a pedigree represents a male showing the trait.

Unit 6: Gene Expression and Regulation

1. 2. 3. RNA polymerase is the enzyme used during transcription.

tRNA molecules match mRNA codons during translation.

Silent mutations do not change the protein; nonsense mutations create a premature stop

codon.

Unit 7: Natural Selection

1. 2. 3. p² represents the frequency of homozygous dominant individuals.

Peppered moths during the Industrial Revolution are an example of directional selection.

Genetic drift is random change in allele frequencies, especially in small populations.

Unit 8: Ecology

1. 2. 3. About 10% of energy is passed to the next trophic level.

Mutualism example: Bees pollinating flowers.

Carrying capacity is the maximum number of individuals an environment can support

sustainably.

Math Skills Review

1. 2. 3. If q² = 0.04, then q = 0.2, p = 0.8.

If observed = expected, then χ² = 0.

The independent variable (temperature) goes on the x-axis.

34📚 AP Biology — Night-Before Exam Cram

Sheet

🧬 Big Themes to Remember:

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Structure determines function (proteins, membranes, DNA)

Energy flows, nutrients cycle (ecosystems, metabolism)

Genes and environments interact (phenotypes aren't always 100% genetic)

Biological systems are interconnected and regulated (feedback loops, homeostasis)

⚡ Essential Content:

Chemistry of Life

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Water is polar ➔ cohesion, adhesion, high specific heat.

Macromolecules = polymers (carbs, proteins, lipids, nucleic acids).

Proteins fold → structure → function!

Cells

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Prokaryotes = no nucleus; eukaryotes = true nucleus.

Organelles:

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Mitochondria ➔ ATP

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Ribosomes ➔ protein synthesis

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Rough ER ➔ modifies proteins

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Golgi ➔ packages

Membranes are semi-permeable ➔ passive vs active transport.

Small cells are better (high SA:V ratio).

Cellular Energetics

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Enzymes lower activation energy.

Photosynthesis: Chloroplasts ➔ Light Reactions (ATP/NADPH) ➔ Calvin Cycle

(glucose).

Cellular Respiration: Mitochondria ➔ Glycolysis ➔ Krebs ➔ ETC ➔ ATP!

Oxygen = final electron acceptor.

Cell Communication & Cycle

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Signals: ligand binds receptor ➔ transduction ➔ response.

Cell cycle: G₁ ➔ S ➔ G₂ ➔ M (PMAT).

Checkpoints guard against mistakes; failures ➔ cancer.

Heredity

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Law of Segregation, Law of Independent Assortment (Mendel).

Punnett Squares: 1:2:1 genotype ratio for Aa × Aa.

Sex-linked = X-chromosome.

Meiosis = makes gametes ➔ variation by crossing over.

Gene Expression & Regulation

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Central Dogma: DNA ➔ RNA ➔ Protein.

Transcription = nucleus; Translation = cytoplasm.

Prokaryotes: lac operon ON when lactose present.

Mutations = source of variation.

Natural Selection

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Variation ➔ survival of the fittest ➔ adaptations.

Hardy-Weinberg:

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p + q = 1 (alleles)

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p² + 2pq + q² = 1 (genotypes)

Types of selection: directional, stabilizing, disruptive.

36Ecology

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Energy flows (10% passed upward each trophic level).

Biogeochemical cycles (carbon, nitrogen, water).

Population growth: exponential vs logistic (carrying capacity).

Species interactions: mutualism, parasitism, competition.