AP Biology Cram Sheet Vocabulary

Vocabulary flashcards covering all key concepts, processes, organelles, and equations across Units 1 through 8 of the AP Biology curriculum.

Cohesion

The property of water molecules sticking to other water molecules via hydrogen bonds, producing surface tension (e.g., allowing a paperclip to float).

Adhesion

The property of water molecules sticking to other polar surfaces, enabling water to rise in plant xylem during transpiration.

High Specific Heat

Water's ability to resist temperature change because its hydrogen bonds absorb energy, helping oceans stabilize climate.

High Heat of Vaporization

The requirement of a high amount of energy to evaporate water, which allows sweating to cool the body.

Ice Density (Water)

The structural property where hydrogen bond lattices push water molecules apart in solid form, making ice less dense than liquid water so it floats.

Carbohydrates

Macromolecules composed of C, H, and O in a 1:2:1 ratio made of monosaccharide monomers; includes cellulose, chitin, starch, and glycogen.

Lipids

Macromolecules composed of C, H, O (and P in phospholipids) with no true monomer; includes saturated fats, unsaturated fats, and phospholipids.

Proteins

Macromolecules composed of C, H, O, N, and S made of amino acid monomers linked by peptide bonds.

Nucleic Acids

Macromolecules composed of C, H, O, N, and P made of nucleotide monomers; includes DNA, RNA, and ATP.

Primary Structure (Protein)

The specific sequence of amino acids in a polypeptide chain.

Secondary Structure (Protein)

Local folding formed by hydrogen bonds on the polypeptide backbone, creating an alpha helix or beta pleated sheet.

Tertiary Structure (Protein)

The overall 3D shape of a polypeptide formed by interactions between amino acid R-groups.

Quaternary Structure (Protein)

The structure resulting from the assembly and interaction of multiple polypeptide chains.

Alpha Linkage

A type of glycosidic linkage found in starch that makes it digestible by humans.

Beta Linkage

A type of glycosidic linkage found in cellulose that renders it NOT digestible by humans.

Ribosomes

Organelles responsible for protein synthesis (translation); free ribosomes make cytosol proteins, while bound ribosomes on the Rough ER make export proteins.

Rough ER

Endoplasmic reticulum studded with ribosomes on its surface that functions in protein folding and packaging for export.

Smooth ER

Endoplasmic reticulum lacking ribosomes that functions in lipid synthesis and metabolic detoxification.

Golgi Apparatus

Organelle known as the cell's mailman that modifies, packages, and ships proteins via vesicles to specific destinations.

Mitochondria

Double-membraned organelle containing folded inner membranes called cristae, acting as the site of cellular respiration and ATP synthesis.

Lysosomes

Animal cell organelles containing an acidic interior and hydrolytic enzymes for intracellular digestion and apoptosis.

Central Vacuole

Plant cell organelle responsible for water storage and maintaining turgor pressure to keep the plant upright.

Simple Diffusion

Passive transport of small, nonpolar molecules (like $O_2$ and $CO_2$) directly through the phospholipid bilayer from high to low concentration without energy.

Facilitated Diffusion

Passive movement of polar or charged molecules (like glucose, ions, and water) across a membrane through transport proteins from high to low concentration.

Active Transport

Energy-requiring movement of molecules against their concentration gradient from low to high concentration, such as the $Na^+/K^+$ pump moving 3 $Na^+$ out and 2 $K^+$ in.

Endocytosis

Energy-requiring import of substances into the cell via vesicles, including phagocytosis for solids and pinocytosis for fluids.

Exocytosis

Energy-requiring export of substances out of the cell via vesicles, such as insulin secretion or neurotransmitter release.

Hypotonic Solution

A solution with a lower solute concentration (higher water potential) than the cell, causing water to flow IN so animal cells lyse and plant cells become turgid.

Hypertonic Solution

A solution with a higher solute concentration (lower water potential) than the cell, causing water to flow OUT so animal cells crenate and plant cells undergo plasmolysis.

Isotonic Solution

A solution with an equal solute concentration to the cell, resulting in no net water movement so animal cells are normal and plant cells are flaccid.

Catalyst

A substance that lowers the activation energy ($E_a$) of a chemical reaction without altering the overall change in free energy ($\Delta G$).

Competitive Inhibition

Reversible inhibition where a molecule blocks the active site of an enzyme; CAN be overcome by increasing substrate concentration.

Non-competitive Inhibition

Inhibition where a molecule binds to an allosteric site and changes enzyme shape; CANNOT be overcome by adding more substrate.

Light Reactions

Photosynthetic reactions in the thylakoid membrane that use $H_2O$ and light to generate ATP, NADPH, and $O_2$ via photolysis.

Calvin Cycle

Photosynthetic reactions in the stroma where Rubisco fixes $CO_2$, consuming ATP and NADPH to synthesize G3P.

Glycolysis

Anaerobic process in the cytoplasm that breaks glucose into 2 pyruvate, yielding a net of 2 ATP and 2 NADH.

Pyruvate Oxidation

Aerobic pathway in the mitochondrial matrix that converts pyruvate into 2 Acetyl-CoA, releasing 2 $CO_2$ and producing 2 NADH per glucose.

Krebs Cycle

Aerobic process in the mitochondrial matrix that breaks down Acetyl-CoA to yield 2 ATP, 6 NADH, 2 $FADH_2$, and 4 $CO_2$ per glucose.

Oxidative Phosphorylation

Process along the inner mitochondrial membrane where oxygen serves as the final electron acceptor to yield $\,\sim 28\text{--}32$ ATP and $H_2O$.

Fermentation

Anaerobic metabolic pathway that functions solely to regenerate $NAD^+$ so glycolysis can continue producing ATP, without yielding extra ATP itself.

Reception

First step of cell signaling where a ligand binds a specific receptor, causing a conformational change (membrane receptors for polar ligands, intracellular receptors for nonpolar ligands).

Transduction

Second step of cell signaling where an intracellular signal is amplified through phosphorylation cascades or second messengers like cAMP and $Ca^{2+}$.

Response

Final step of cell signaling resulting in targeted cellular actions such as gene expression, enzyme activation, apoptosis, or ion channel opening.

Negative Feedback

A regulatory mechanism that returns a system to a set point to maintain homeostasis (e.g., insulin lowering blood glucose levels).

Positive Feedback

A regulatory mechanism that amplifies a stimulus to drive a biological process to completion (e.g., oxytocin inducing labor during childbirth).

Interphase

The cell cycle stage comprising $G_1$, S, and $G_2$ phases, where cells spend $\,\sim 90\%$ of their life growing and replicating DNA.

Proto-oncogene

A normal gene involved in stimulating cell growth; when mutated into an oncogene, it drives continuous, unregulated cell division.

Tumor Suppressor Gene

A gene (such as p53) that functions as a cellular brake to inhibit division or repair DNA damage; loss of function can lead to cancer.

Meiosis I

Cell division where homologous chromosomes separate; includes crossing over at chiasmata during Prophase I and independent assortment at Metaphase I.

Meiosis II

Cell division where sister chromatids separate, resulting in 4 genetically unique haploid cells.

Incomplete Dominance

Inheritance pattern where the heterozygous phenotype presents as a blend or intermediate of both homozygous phenotypes (e.g., red and white flowers yielding pink).

Codominance

Inheritance pattern where both alleles are fully and simultaneously expressed in the heterozygous condition (e.g., AB blood type).

Pleiotropy

A genetic condition where a single gene mutation causes multiple distinct phenotypic effects (e.g., sickle cell disease).

Mitochondrial Inheritance

Maternal inheritance pattern where all offspring of an affected mother inherit the trait, while affected fathers never pass it to their offspring.

DNA Polymerase III

Enzyme that synthesizes new DNA strands in the $5' \rightarrow 3'$ direction, requiring a free $3'\text{-OH}$ group provided by an RNA primer.

Helicase

Enzyme that unwinds the DNA double helix at the replication fork.

Primase

Enzyme that lays down short RNA primers to provide a free $3'\text{-OH}$ group for DNA synthesis.

DNA Polymerase I

Enzyme responsible for removing RNA primers and replacing them with DNA nucleotides during DNA replication.

DNA Ligase

Enzyme that seals nicks in the sugar-phosphate backbone by joining Okazaki fragments together on the lagging strand.

Eukaryotic mRNA Processing

Post-transcriptional modifications including the addition of a $5'$ GTP cap, a $3'$ Poly-A tail, and splicing (exons expressed, introns removed).

Lac Operon

An inducible bacterial operon that is OFF by default; binding of allolactose (inducer) inactivates the repressor to turn gene expression ON.

Trp Operon

A repressible bacterial operon that is ON by default; tryptophan acts as a co-repressor to activate the repressor and turn gene expression OFF.

Epigenetics

Heritable changes in gene expression without altering the DNA sequence; DNA methylation turns genes OFF, while histone acetylation turns genes ON.

Stabilizing Selection

Natural selection favoring intermediate phenotypes over extreme ones, which narrows the bell curve and reduces overall variation.

Directional Selection

Natural selection favoring one extreme phenotype, causing the population's trait bell curve to shift toward that favored extreme.

Disruptive Selection

Natural selection favoring both extreme phenotypes over the intermediate, splitting the bell curve into two peaks and potentially leading to speciation.

Hardy-Weinberg Equilibrium

Model describing a non-evolving population with constant allele ($p + q = 1$) and genotype ($p^2 + 2pq + q^2 = 1$) frequencies under five specific conditions.

Bottleneck Effect

A form of genetic drift resulting from a severe disaster that randomly shrinks population size and changes allele frequencies independent of fitness.

Founder Effect

A form of genetic drift resulting from a small group colonizing a new location, establishing allele frequencies based on chance rather than fitness.

Exponential Growth Model

Population growth described by $\frac{dN}{dt} = r_{\text{max}} N$, resulting in a J-shaped curve under unlimited resource conditions.

Logistic Growth Model

Population growth described by $\frac{dN}{dt} = r_{\text{max}} N \left(\frac{K - N}{K}\right)$, resulting in an S-shaped curve as resources become limited up to carrying capacity ($K$).

10% Rule

Principle stating that only about $10\%$ of energy is transferred from one trophic level to the next, while $90\%$ is lost as heat or waste.

Keystone Species

A species that exerts a disproportionately large effect on its ecosystem structure, whose removal causes a trophic cascade and ecosystem collapse.

Invasive Species

Non-native organisms lacking natural predators that experience exponential growth, outcompeting native species and reducing ecosystem biodiversity.

Biomagnification

The progressive concentration of toxins at higher levels of a food chain, affecting top apex predators most severely.

Eutrophication

Environmental phenomenon where fertilizer runoff fuels algal blooms, which leads to bacterial oxygen depletion and aquatic dead zones.