BIOL-105 Introduction to Biology - Exam 1 Practice Flashcards

Comprehensive Question and Answer practice flashcards covering introductory biology concepts, cell chemistry, biological macromolecules, water properties, pH, and taxonomy.

What is biology?

The science that studies life — how living things are organized, function, reproduce, adapt, and use energy.

Name 5 features of living things

Highly organized; respond to stimuli; grow and reproduce; adapt to the environment; process energy.

What are the 3 domains of life?

Bacteria, Archaea, and Eukarya.

Which domains are prokaryotes?

Bacteria and Archaea — no nucleus, no membrane-bound organelles.

Which domain is eukaryotic?

Eukarya — nucleus plus organelles; includes plants, animals, fungi, protists.

Taxonomic ranks from broadest to most specific

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Human scientific name

Homo sapiens (Domain Eukarya, Kingdom Animalia).

Levels of organization (small → large)

Atom → molecule → organelle → cell → tissue → organ → organ system → organism → population → community → ecosystem → biosphere.

What is an element?

A substance that cannot be broken down chemically into something else (C, H, O, N, etc.).

What is an atom?

The smallest unit of an element that still has that element’s properties (protons, neutrons, electrons).

Ionic bond

Electrons are transferred from one atom to another.

Covalent bond

Electrons are shared between atoms.

4 major classes of biological molecules

Carbohydrates, lipids, proteins, nucleic acids.

Carbohydrate general formula

(CH₂O)ₙ

Monosaccharide

One sugar. Examples: glucose, fructose, galactose. Formula often C₆H₁₂O₆.

Disaccharide

Two sugars joined. Examples: sucrose, lactose, maltose.

Polysaccharide

Long chain of sugars.

Starch

Plant energy storage.

Glycogen

Animal energy storage (liver and muscle). Short-term.

Cellulose

Plant cell walls. We cannot digest it (fiber).

Chitin

Exoskeletons of insects, spiders, crabs. Has nitrogen.

3 fates of blood glucose

Burn immediately for energy; store short-term as glycogen; convert long-term to fat.

Are lipids hydrophilic or hydrophobic?

Hydrophobic — they do not mix with water.

Jobs of lipids

Energy storage, cushioning, insulation, membranes, hormones.

Saturated fat

No double bonds (max hydrogens), straight, solid at room temp, mostly animal (butter, meat).

Unsaturated fat

One or more double bonds, bent, liquid at room temp, mostly plant oils.

Phospholipid structure in membranes

Hydrophilic phosphate heads face water; hydrophobic fatty-acid tails face inward. Two layers = bilayer.

Steroids

Lipids with 4 fused carbon rings. Examples: cholesterol, estrogen, testosterone.

Cholesterol’s job in animal membranes

Keeps the membrane fluid and stable.

What are proteins made of?

Amino acids (20 kinds) joined by peptide bonds.

Primary protein structure

The amino-acid sequence.

Secondary protein structure

α-helix (corkscrew) or β-pleated sheet. Held by hydrogen bonds.

Tertiary protein structure

The full 3-D fold of one chain.

Quaternary protein structure

Two or more polypeptide chains together (example: hemoglobin has 4).

Why protein shape matters

Shape determines function. Change the sequence a little → protein may fail.

Enzyme

A protein that speeds a chemical reaction without being used up. Metabolism = all chemical reactions in an organism.

Nucleotide — 3 parts

Nitrogenous base + pentose (5-carbon) sugar + phosphate.

DNA vs RNA — sugar

DNA = deoxyribose. RNA = ribose.

DNA vs RNA — bases

DNA: A, T, C, G. RNA: A, U, C, G.

(DNA has T; RNA has U.)

DNA vs RNA — strands

DNA is double-stranded helix. RNA is usually single-stranded.

DNA base-pairing rules

A pairs with T. G pairs with C.

RNA base-pairing (when it folds)

A pairs with U. G pairs with C.

Purines vs pyrimidines

Purines (2 rings): A and G.Pyrimidines (1 ring): C, T, and U.

Why is water polar?

Uneven charge: oxygen is slightly negative, hydrogens slightly positive. Lets water form hydrogen bonds.

Hydrophilic vs hydrophobic

Hydrophilic = mixes with water (polar). Hydrophobic = fears water (nonpolar, like oil).

Cohesion

Water sticks to water (hydrogen bonds). Makes surface tension; helps pull water up plants.

Adhesion

Water sticks to other surfaces (cell walls). Helps capillary action up stems.

Why ice floats

Frozen water makes a spaced-out crystal that is less dense than liquid water. Lakes don’t freeze solid; life can survive underneath.

Water as a solvent

Water dissolves many polar and ionic substances. Oil does not dissolve in water.

High heat capacity

Water absorbs a lot of heat with only a small temperature change. Stabilizes climate and body temperature.

Evaporative cooling (sweat)

Heat is used to break H-bonds and turn sweat into vapor, which cools the body.

pH scale

0 = acid, 7 = neutral, 14 = base. Each step is a 10× change in H⁺.

Acid vs base

Acids release H⁺. Bases remove H⁺.

Buffer

A solution that resists sudden pH change. Blood uses buffers so proteins keep working.

Aquaporin

A protein channel that lets water cross cell membranes quickly.