AP Biology Exam Review Flashcards

Comprehensive flashcards covering key concepts from AP Biology lecture notes, designed to aid in exam preparation.

What are the "Big Six" elements essential for life?

Which of the following are the "Big Six" elements essential for life?

(a) Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), and Sulfur (S)

(b) Sodium (Na), Chlorine (Cl), Potassium (K), Iron (Fe), Magnesium (Mg), Calcium (Ca)

(c) Copper (Cu), Zinc (Zn), Selenium (Se), Iodine (I), Fluorine (F), Manganese (Mn)

(d) Boron (B), Molybdenum (Mo), Vanadium (V), Chromium (Cr), Cobalt (Co), Silicon (Si)

Explanation: The "Big Six" elements are

Why is carbon's tetravalence important in biological molecules?

It allows carbon to form four stable covalent bonds, creating diverse and complex molecular architectures, including chains, branches, and rings.

How do differences in electronegativity influence molecular interactions?

They lead to polar covalent bonds and partial charges within molecules, affecting how they interact.

What is the significance of functional groups in biomolecules?

Functional groups confer distinct chemical properties and reactivity, enabling prediction of molecular behavior.

Explain why water is considered a polar molecule.

Water's bent geometry and oxygen's higher electronegativity result in a dipole moment with partial negative charge on oxygen and partial positive charges on hydrogen.

What is hydrogen bonding and why is it important for water's properties?

Hydrogen bonding is the attraction between partially positive hydrogen of one water molecule and partially negative oxygen of another. It causes cohesion, adhesion, high specific heat, and other unique properties.

Define cohesion in the context of water molecules.

Cohesion is the attraction between water molecules due to hydrogen bonding, resulting in high surface tension and aiding water transport in plants.

Define adhesion in the context of water molecules.

Adhesion is the attraction between water molecules and other polar substances, contributing to capillary action and water transport in plants.

Why does water have a high specific heat?

Water can absorb large amounts of heat with only a small temperature increase due to hydrogen bonding.

How does water's high heat of vaporization benefit organisms?

It allows for efficient evaporative cooling as significant energy is required to break hydrogen bonds to convert liquid water to gas.

Explain the density anomaly of water (ice floats).

Ice is less dense than liquid water because hydrogen bonds in ice form a spacious crystalline lattice, preventing aquatic ecosystems from freezing solid.

Why is water considered a versatile solvent?

Water's polarity allows it to form hydration shells around ions and polar molecules, effectively dissolving them.

What is the difference between hydrophilic and hydrophobic substances?

Hydrophilic substances are water-loving and dissolve readily, while hydrophobic substances are nonpolar and do not dissolve in water.

Define amphipathic molecules and give an example.

Amphipathic molecules have both hydrophilic and hydrophobic regions (e.g., phospholipids).

What is an isomer?

Molecules with the same molecular formula but different structural arrangements.

Describe the process of forming macromolecules from monomers.

Monomers are joined through dehydration reactions (water is removed) to form polymers, and polymers are broken down by hydrolysis reactions (water is added).

List examples of monosaccharides.

Glucose, fructose, galactose.

How are disaccharides formed?

By joining two monosaccharides via a glycosidic linkage (e.g., sucrose = glucose + fructose).

What are the main functions of carbohydrates?

Primarily energy storage (short-term) and structural support; also involved in cell recognition and signaling.

What are the four levels of protein structure?

Primary, secondary, tertiary, and quaternary structure.

Describe protein denaturation.

Denaturation is the loss of a protein's native conformation due to factors like extreme temperature or pH changes, leading to loss of function.

List functions of proteins.

Enzymatic catalysis, structural support, movement, transport, signaling, defense, and storage.

Describe the structure of a triglyceride.

Composed of a glycerol molecule esterified to three fatty acid molecules.

What is the structural difference between saturated and unsaturated fatty acids?

Saturated fatty acids have no carbon-carbon double bonds, while unsaturated fatty acids contain one or more double bonds.

What is the main function of phospholipids?

Major structural component of cell membranes, forming a phospholipid bilayer.

What is the basic structure of a steroid?

Lipids characterized by a carbon skeleton consisting of four fused rings.

List the components of a nucleotide.

A nitrogenous base, a pentose sugar, and a phosphate group.

What are the base pairing rules in DNA?

Adenine pairs with Thymine (A-T), and Cytosine pairs with Guanine (C-G).

What are the key differences between DNA and RNA?

DNA is double-stranded with deoxyribose sugar and thymine, while RNA is single-stranded with ribose sugar and uracil.

List three types of RNA and their functions.

mRNA (carries genetic information), tRNA (carries amino acids), rRNA (structural and catalytic component of ribosomes).

What are the primary differences between prokaryotic and eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells possess both.

Describe the function of the nuclear envelope.

Double membrane with nuclear pores that regulate molecule passage between the nucleus and cytoplasm.

Where are ribosomes assembled?

In the nucleolus.

What is the difference between free and bound ribosomes?

Free ribosomes synthesize proteins that function within the cytosol, while bound ribosomes synthesize proteins destined for secretion or membranes.

What is the function of the smooth endoplasmic reticulum (SER)?

Lipid synthesis, detoxification, carbohydrate metabolism, and calcium ion storage.

What is the function of the Golgi apparatus?

Modifies, sorts, and packages proteins and lipids received from the ER.

What is the function of lysosomes?

Intracellular digestion, autophagy, and phagocytosis.

What is the function of peroxisomes?

Breakdown of fatty acids and detoxification of harmful compounds; key byproduct is hydrogen peroxide.

What is the function of mitochondria?

Site of aerobic respiration, generating most of the cell's ATP.

What is the function of chloroplasts?

Site of photosynthesis, converting light energy into chemical energy.

What is the function of vacuoles?

Storage of water, ions, nutrients, and waste products; maintains turgor pressure in plants.

Describe the function of microfilaments.

Maintain cell shape, muscle contraction, cell motility, and cell division.

What are the components of plant cell walls?

Primarily composed of cellulose, with other polysaccharides like hemicellulose and pectin.

What is the function of the extracellular matrix (ECM)?

Provides structural and biochemical support to surrounding cells; involved in cell adhesion, migration, and signaling.

Describe the fluid mosaic model of the plasma membrane.

The plasma membrane is a fluid structure with a mosaic of various proteins embedded in a phospholipid bilayer.

What is the role of cholesterol in the animal cell membrane?

Affects membrane fluidity; reduces fluidity at moderate temperatures and prevents solidification at low temperatures.

How do glycolipids and glycoproteins function in the plasma membrane?

Involved in cell-cell recognition and interactions.

What types of molecules can readily pass through the plasma membrane via simple diffusion?

Small, nonpolar molecules (e.g., O2, CO2).

Describe facilitated diffusion.

Movement of a substance across a membrane down its concentration gradient with the help of membrane proteins (transport proteins).

How do channel proteins aid in membrane transport?

Provide hydrophilic channels for specific ions or small polar molecules to pass through.

How do carrier proteins aid in membrane transport?

Bind to specific molecules, undergo a conformational change, and release the molecule on the other side of the membrane.

Define osmosis.

The diffusion of water across a selectively permeable membrane from high to low water concentration.

What happens to an animal cell in a hypotonic solution?

Water moves into the cell, causing it to swell and potentially lyse (cytolysis).

What happens to a plant cell in a hypotonic solution?

Water moves into the cell, the cell becomes turgid

Describe active transport.

Movement of substances across the membrane against their concentration gradient, requiring energy (ATP) and transport proteins.

What is the function of the sodium-potassium pump?

Actively transports sodium ions out of the cell and potassium ions into the cell, maintaining electrochemical gradients.

What is cotransport?

The movement of one solute down its concentration gradient drives the movement of another solute against its concentration gradient.

Explain endocytosis.

The cell takes in macromolecules by forming new vesicles from the plasma membrane.

Explain exocytosis.

The cell secretes macromolecules by the fusion of vesicles with the plasma membrane.

What is the role of enzymes in biochemical reactions?

Enzymes act as biological catalysts, speeding up biochemical reactions without being consumed in the process.

How do enzymes affect activation energy?

Enzymes lower the activation energy (Ea), the initial energy required to start a reaction.

What is an enzyme's active site?

A region with a unique three-dimensional shape that binds to a specific substrate molecule(s).

How does temperature affect enzyme activity?

Enzyme activity increases with temperature up to an optimal temperature, beyond which the enzyme denatures and activity decreases sharply.

What is Vmax in enzyme kinetics?

The maximum reaction rate when all active sites are saturated with substrate.

Define cofactors and coenzymes.

Non-protein helpers required for enzyme activity; coenzymes are organic cofactors often derived from vitamins.

How do competitive inhibitors affect enzyme activity?

Bind to the active site, competing with the substrate; can be overcome by increasing substrate concentration.

How do noncompetitive inhibitors affect enzyme activity?

Bind to another part of the enzyme (allosteric site), causing a conformational change in the active site and reducing its effectiveness.

What is the overall equation for photosynthesis?

6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2

Where do the light-dependent reactions occur?

In the thylakoid membranes.

What is the role of chlorophyll in photosynthesis?

Absorbs light energy, initiating the light-dependent reactions.

What happens during water splitting (photolysis)?

Water molecules are split, releasing electrons, protons (H+), and oxygen gas (O2) as a byproduct.

How is ATP synthesized during the light-dependent reactions?

The proton gradient across the thylakoid membrane drives the synthesis of ATP by ATP synthase via chemiosmosis.

What is the role of NADPH in photosynthesis?

An electron carrier generated during the light-dependent reactions; used in the Calvin cycle.

Where does the Calvin cycle occur?

In the stroma.

What is carbon fixation?

CO2 from the atmosphere is incorporated into an organic molecule, ribulose-1,5-bisphosphate (RuBP), with the help of RuBisCO.

What is photorespiration?

A process that occurs when RuBisCO binds to O2 instead of CO2, reducing photosynthetic efficiency.

How do C4 and CAM plants minimize photorespiration?

C4 plants spatially separate carbon fixation and the Calvin cycle; CAM plants temporally separate them.

What is the overall equation for cellular respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Where does glycolysis occur?

In the cytoplasm.

What is the net gain of ATP from glycolysis?

2 ATP per glucose molecule.

Where does pyruvate oxidation occur?

In the mitochondrial matrix.

Where does the Krebs cycle occur?

In the mitochondrial matrix.

What are the products of the Krebs cycle per glucose molecule?

6 NADH, 2 FADH2, and 2 ATP.

Where does oxidative phosphorylation occur?

In the inner mitochondrial membrane.

What is the role of the electron transport chain (ETC) in cellular respiration?

NADH and FADH2 donate their high-energy electrons to a series of protein complexes, creating a proton gradient.

What is chemiosmosis?

The proton gradient drives the synthesis of ATP by ATP synthase.

What is the final electron acceptor in the electron transport chain?

Oxygen, combining with electrons and protons to form water.

What is the theoretical maximum ATP yield per glucose molecule during aerobic respiration?

Around 36-38 ATP.

Define fermentation.

Anaerobic respiration that regenerates NAD+ so that glycolysis can continue.

What are the end products of lactic acid fermentation?

Lactate (lactic acid) and NAD+.

What are the end products of alcohol fermentation?

Ethanol, carbon dioxide, and NAD+.

Define signal transduction pathway.

A series of steps by which a signal on a cell's surface is converted into a specific cellular response.

Describe endocrine signaling.

Signaling molecules (hormones) are secreted into the bloodstream and travel long distances to reach target cells.

Describe paracrine signaling.

The signaling cell releases a signal that acts on nearby target cells.

Describe autocrine signaling.

The target cell is also the signaling cell: it releases a signal that binds to receptors on its own surface.

Describe juxtacrine signaling.

Signaling occurs through direct physical contact between cells

Name three types of plasma membrane receptors.

G protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs), and ion channel receptors.

What is the role of second messengers?

Small, non-protein molecules or ions that relay signals from the receptor to other components of the signal transduction pathway.

Describe protein phosphorylation and dephosphorylation.

Protein kinases add phosphate groups (phosphorylation), often activating proteins; protein phosphatases remove phosphate groups (dephosphorylation), often inactivating proteins.

What are potential cellular responses to cell signaling?

Changes in gene expression, activation of enzymes, cytoskeletal rearrangement, cell division, and apoptosis.