AP Biology First Quiz

What are the six elements common to all living organisms?

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

What property of water results from its polarity and hydrogen bonding?

Cohesion (water molecules sticking to other water molecules)

What property of water allows it to stick to other surfaces?

Adhesion

What measurement describes water's surface "skin-like" property?

Surface tension

What term describes a substance that dissolves in water?

Hydrophilic (e.g., salts, sugars)

What term describes substances that don't dissolve in water?

Hydrophobic (e.g., oils, fats)

Is ice more or less dense than liquid water?

Less dense - ice floats

Why is ice floating biologically important?

Insulates aquatic ecosystems, prevents complete freezing

What is specific heat?

Energy required to raise 1g of substance by 1°C

Does water have high or low specific heat?

High - buffers temperature changes

How does water moderate coastal climates?

Absorbs/releases heat slowly, reducing temperature extremes

What process occurs when water molecules escape as vapor?

Evaporation

What property allows water to dissolve many substances?

Polarity - makes it the "universal solvent"

Define surface tension.

Cohesive forces creating surface "film" (e.g., water striders walk on water)

Differentiate adhesion and cohesion.

Adhesion: water sticks to other surfaces; Cohesion: water sticks to itself

Are car windshields polar or nonpolar?

Polar (silica bonds) - explains water droplet adhesion

How does Gore-Tex® work?

Micro-pores allow water vapor through but block liquid droplets via surface tension

Define an acid.

Substance that donates H⁺ ions (pH < 7)

Define a base.

Substance that accepts H⁺ ions (pH > 7)

What are buffers?

Substances that resist pH changes (e.g., blood bicarbonate)

Calculate pH of 0.3M HCl.

pH = -log(0.3) = 0.52

What element is fundamental to all biomolecules?

Carbon

Why is carbon ideal for biomolecules?

Forms 4 stable covalent bonds, enabling complex structures

Define hydrocarbon.

Molecule with only C and H (e.g., methane, propane)

Which C-C bond stores the most energy?

Triple bond (C≡C)

What functional group is -OH?

Hydroxyl (polar, forms H-bonds)

What functional group is -COOH?

Carboxyl (acidic, donates H⁺)

What functional group is -NH₂?

Amino (basic, accepts H⁺)

What functional group is -SH?

Sulfhydryl (forms disulfide bridges)

What functional group is -PO₄?

Phosphate (energy transfer, ATP)

Define monomer.

Single molecular subunit (e.g., amino acid)

Define polymer.

Chain of monomers (e.g., protein)

What reaction builds polymers?

Dehydration synthesis (releases water)

What reaction breaks polymers?

Hydrolysis (consumes water)

List elements in carbohydrates.

C, H, O (1:2:1 ratio)

List elements in lipids.

C, H, O (no fixed ratio)

List elements in proteins.

C, H, O, N, S

List elements in nucleic acids.

C, H, O, N, P

What are carbohydrate monomers?

Monosaccharides (e.g., glucose)

What are lipid components?

Glycerol + fatty acids

What are protein monomers?

Amino acids

What are nucleic acid monomers?

Nucleotides

What bonds link carbohydrates?

Glycosidic bonds

What bonds link proteins?

Peptide bonds

What bonds link nucleic acids?

Phosphodiester bonds

What bonds form lipids?

Ester bonds

What carbohydrate stores energy in plants?

Starch

What carbohydrate stores energy in animals?

Glycogen

What makes plant cell walls?

Cellulose

What makes insect exoskeletons?

Chitin (contains nitrogen)

What are saturated fats?

No double bonds, solid at room temp (e.g., butter)

What are unsaturated fats?

Contain double bonds, liquid at room temp (e.g., olive oil)

What lipids form cell membranes?

Phospholipids

What are protein functions?

Enzymes, structure, transport, signaling

Draw amino acid structure.

Central carbon with: amino group (-NH₂), carboxyl group (-COOH), hydrogen, R-group

What bonds form between amino acids?

Peptide bonds (covalent)

What determines protein directionality?

N-terminus (amino end) to C-terminus (carboxyl end)

What are nucleic acid functions?

Store/transmit genetic information

DNA sugar?

Deoxyribose

RNA sugar?

Ribose

DNA bases?

A, T, C, G

RNA bases?

A, U, C, G

DNA structure?

Double-stranded helix

RNA structure?

Single-stranded

Where is DNA in eukaryotes?

Nucleus and mitochondria

Where is RNA in eukaryotes?

Nucleus and cytoplasm

How are DNA, RNA, and protein linked?

DNA → (transcription) → RNA → (translation) → Protein