AP Biology Units 1-4

Why is water essential to life?

Water is polar, so it dissolves many substances and helps regulate temperature. Example: blood is mostly water, which helps transport nutrients.

What does it mean that water is polar?

Water has uneven charge, with oxygen slightly negative and hydrogen slightly positive.

What is hydrogen bonding in water?

A weak attraction between water molecules. Example: hydrogen bonds help give water surface tension.

What is cohesion?

Water molecules sticking to each other. Example: water beads on a surface.

What is adhesion?

Water sticking to other materials. Example: water climbing plant xylem.

Why does water help organisms regulate temperature?

Water resists temperature change. Example: oceans keep climates stable.

Why does ice float?

Solid water is less dense than liquid water because of hydrogen bonding.

Why is water a good solvent?

It dissolves ionic and polar substances. Example: salt dissolves in water.

What are elements in biology?

Pure substances made of one kind of atom. Example: carbon, oxygen, nitrogen.

Why is carbon so important?

Carbon can form 4 bonds, making complex molecules. Example: it forms the backbone of glucose.

What is a macromolecule?

A large biological molecule. Examples: proteins, DNA, starch, fats.

What is a polymer?

A molecule made of repeating monomers. Example: starch is a polymer of glucose.

What is a monomer?

A small building block of a polymer. Example: amino acids are protein monomers.

What is dehydration synthesis?

Joining monomers by removing water. Example: linking amino acids into a protein.

What is hydrolysis?

Breaking polymers by adding water. Example: digestion breaks starch into glucose.

What do carbohydrates do?

Provide energy and structure. Example: glucose gives quick energy.

What is a monosaccharide?

A single sugar. Example: glucose.

What is a disaccharide?

Two sugars joined together. Example: sucrose.

What is a polysaccharide?

Many sugars linked together. Example: starch.

What is starch?

Energy storage in plants. Example: potatoes store starch.

What is glycogen?

Energy storage in animals. Example: liver cells store glycogen.

What is cellulose?

Structural carbohydrate in plants. Example: it makes plant cell walls rigid.

What do lipids do?

Store energy long-term and form membranes. Example: body fat stores energy.

Why are lipids hydrophobic?

They are nonpolar, so they do not mix with water.

What is a triglyceride?

A fat made of glycerol and 3 fatty acids. Example: butter contains triglycerides.

What is a saturated fat?

A fat with no double bonds. Example: butter is high in saturated fat.

What is an unsaturated fat?

A fat with one or more double bonds. Example: olive oil.

What are phospholipids?

Membrane molecules with a hydrophilic head and hydrophobic tails. Example: they form the cell membrane.

What are steroids?

Lipids with 4 fused rings. Example: cholesterol and testosterone.

What are proteins made of?

Amino acids. Example: hemoglobin is a protein.

What is an amino acid?

The monomer of proteins. Each has an amino group, carboxyl group, and R group.

Why are proteins important?

They do most cell jobs. Example: enzymes, transport proteins, and antibodies.

What are enzymes?

Proteins that speed up reactions. Example: amylase breaks down starch.

What affects enzyme activity?

Temperature, pH, and substrate amount. Example: high heat can stop enzyme function.

What does denatured mean?

A protein loses shape and function. Example: egg white changes when cooked.

What are nucleic acids?

DNA and RNA, which store genetic information.

What is a nucleotide?

The monomer of nucleic acids. It has a sugar, phosphate, and base.

What does DNA do?

Stores hereditary information. Example: genes are made of DNA.

What does RNA do?

Helps make proteins. Example: mRNA carries instructions to ribosomes.

What are the 4 levels of protein structure?

Primary, secondary, tertiary, quaternary. Example: hemoglobin has quaternary structure.

What is cell theory?

All living things are made of cells, cells are the basic unit of life, and cells come from preexisting cells.

What do all cells have?

DNA, ribosomes, cytoplasm, and a cell membrane.

What does the cell membrane do?

Controls what enters and leaves the cell.

What is the fluid mosaic model?

A flexible membrane made of phospholipids and proteins. Example: membrane proteins help move materials.

What is a phospholipid bilayer?

Two layers of phospholipids with heads outward and tails inward.

What is selective permeability?

The membrane lets some things pass but blocks others.

What is passive transport?

Movement without energy. Example: oxygen diffusing into cells.

What is diffusion?

Movement from high to low concentration. Example: perfume spreading in a room.

What is osmosis?

Diffusion of water. Example: plant cells gain water in freshwater.

What is facilitated diffusion?

Movement through membrane proteins without energy. Example: glucose entering cells through a transport protein.

What is active transport?

Movement that requires energy. Example: the sodium-potassium pump.

What is endocytosis?

The cell brings material in using vesicles. Example: white blood cells engulf bacteria.

What is exocytosis?

The cell releases material using vesicles. Example: cells releasing hormones.

What is a prokaryotic cell?

A cell without a nucleus. Example: bacteria.

What is a eukaryotic cell?

A cell with a nucleus. Example: plant and animal cells.

What does the nucleus do?

Stores DNA and controls cell activity.

What do ribosomes do?

Make proteins. Example: ribosomes build insulin.

What does rough ER do?

Makes and helps move proteins.

What does smooth ER do?

Makes lipids and helps detoxify chemicals.

What does the Golgi apparatus do?

Modifies and packages molecules. Example: it packages proteins for secretion.

What do lysosomes do?

Break down waste and old cell parts.

What do vacuoles do?

Store water, food, and waste. Example: plant central vacuole stores water.

What do mitochondria do?

Make ATP through cellular respiration.

What do chloroplasts do?

Carry out photosynthesis. Example: found in plant cells.

What is compartmentalization?

Organelles separate jobs inside the cell.

Why are cells small?

Small cells exchange materials faster.

Why does surface area to volume ratio matter?

Bigger cells have trouble moving materials in and out fast enough.

What is the cytoskeleton?

A network that supports shape and movement. Example: helps chromosomes move during cell division.

What is the cell wall?

A rigid outer layer for support. Example: plant cell walls contain cellulose.

How are plant and animal cells different?

Plant cells have chloroplasts, a cell wall, and a large vacuole; animal cells do not.

What is cellular energetics?

The study of how cells capture, store, and use energy.

What is ATP?

Adenosine triphosphate, the main energy currency of the cell.

Why is ATP useful?

Because it can quickly release energy for cellular work.

What is the role of enzymes in metabolism?

They speed up chemical reactions by lowering activation energy.

What is activation energy?

The energy needed to start a chemical reaction.

What affects enzyme activity?

Temperature, pH, substrate concentration, and inhibitors.

What is the active site of an enzyme?

The region where the substrate binds.

What is a substrate?

The reactant an enzyme acts on.

What is the induced fit model?

Enzyme and substrate change shape slightly to fit together better.

What is denaturation?

When a protein loses its shape and function, often due to heat or pH.

What is feedback inhibition?

End product of a pathway shuts down an earlier enzyme to stop overproduction.

What is cellular respiration?

The process that breaks down glucose to make ATP.

What are the three main stages of cellular respiration?

Glycolysis, citric acid cycle, and oxidative phosphorylation.

Where does glycolysis occur?

In the cytoplasm.

What is the main product of glycolysis?

2 pyruvate, 2 ATP net, and 2 NADH.

Does glycolysis require oxygen?

No, it is anaerobic.

What happens to pyruvate before the citric acid cycle?

It is converted to acetyl-CoA.

Where does the citric acid cycle occur?

In the mitochondrial matrix.

What is produced in the citric acid cycle?

CO2, NADH, FADH2, and ATP.

Where does oxidative phosphorylation occur?

In the inner mitochondrial membrane.

What is the electron transport chain?

A series of proteins that pass electrons and pump protons.

What is chemiosmosis?

The use of a proton gradient to power ATP synthesis.

What does ATP synthase do?

Uses proton flow to make ATP from ADP and phosphate.

What is the final electron acceptor in aerobic respiration?

Oxygen.

Why is oxygen important in cellular respiration?

It accepts electrons and allows the ETC to keep working.

What is fermentation?

An anaerobic process that regenerates NAD+ so glycolysis can continue.

What are the two main types of fermentation?

Lactic acid fermentation and alcohol fermentation.

What is the purpose of fermentation?

To keep making ATP when oxygen is unavailable.

What is lactic acid fermentation?

Pyruvate is converted to lactate.

What is alcohol fermentation?

Pyruvate is converted to ethanol and CO2.