COLLEGE BIO EXAM

What are the characteristics of life?

The characteristics of life include organization, metabolism, homeostasis, growth, reproduction, response to stimuli, and adaptation through evolution.

What is biology?

Biology is the scientific study of living organisms.

Define emergent properties.

Emergent properties are characteristics of a system that arise from the interactions of its components, rather than from the individual parts themselves.

What is homeostasis?

Homeostasis is the ability of an organism or system to maintain a stable internal environment despite changes in external conditions.

Outline the hierarchy of life from smallest to largest.

The hierarchy of life includes atoms, molecules, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, and the biosphere.

What is the scientific method?

Observation → Hypothesis → Prediction → Testing → Results → Conclusion → Share Results

What is a hypothesis?

A testable explanation for an observation.

What is a theory in science?

A well-supported explanation based on evidence (e.g., Cell theory, Evolution).

Cell Theory? Who contributed?

All organisms are made of cells; cells come from preexisting cells.
Scientists: Schleiden & Schwann (1830s), Virchow (“cells come from cells”).

What is the role of evolution in biology?

It explains unity (shared traits) and diversity (variations) through changes in heritable traits over generations.

What are protons, neutrons, and electrons?

Proton (+, nucleus), Neutron (0, nucleus), Electron (–, orbitals).

What is an isotope?

Atoms with the same proton number but different neutron numbers.

What is electronegativity?

How strongly an atom attracts electrons.

What types of chemical bonds exist?

Covalent (shared electrons), Ionic (electron transfer), Hydrogen bonds (weak attraction between polar molecules).

Why is water polar?

Oxygen is more electronegative and pulls electrons toward itself.

What properties of water make life possible?

Cohesion, adhesion, surface tension, high heat capacity, universal solvent, density changes (ice floats).

What is pH?

Measure of H+ concentration; lower = acidic; higher = basic.

What is a buffer?

Substance that resists pH change (e.g., bicarbonate).

Why is carbon the backbone of life?

It forms 4 bonds → can build large, complex molecules.

Important functional groups and roles?

Hydroxyl (alcohols), Carboxyl (acids), Amino (proteins), Phosphate (energy/ATP), Methyl (gene expression).

What are free radicals?

Highly reactive atoms/molecules with unpaired electrons can cause cellular damage.

What is a monomer vs polymer?

Monomer = single building block; Polymer = chain of monomers.

What is dehydration synthesis?

Reaction that builds polymers by removing water.

What is hydrolysis?

Reaction that breaks polymers using water.

Examples of monosaccharides?

Glucose, fructose, galactose.

Examples of polysaccharides?

Starch (plants), Glycogen (animals), Cellulose (plant cell walls), Chitin (fungi/exoskeletons).

Function of carbohydrates?

Quick energy & structural materials.

What makes lipids hydrophobic?

Mostly nonpolar hydrocarbon chains.

Types of lipids?

Triglycerides, phospholipids, steroids, waxes.

Structure of phospholipid + importance?

Hydrophilic head + hydrophobic tails; forms cell membranes.

Saturated vs unsaturated fats?

Saturated: no double bonds → solid at room temp.
Unsaturated: double bonds → liquid.

Monomer of proteins?

Amino acids.

What determines protein function?

Shape (primary, secondary, tertiary, quaternary structure).

What causes denaturation?

Heat, pH, salts → disrupt protein shape.

Enzyme role?

Catalysts that lower activation energy.

What does “enzyme specificity” mean?

Each enzyme only fits one substrate (lock-and-key or induced fit).

Monomers of nucleic acids?

Nucleotides: sugar + phosphate + base.

DNA vs RNA?

DNA = double-stranded, deoxyribose, A-T-C-G
RNA = single-stranded, ribose, A-U-C-G

Function of nucleic acids?

DNA stores genetic information; RNA is used in protein synthesis.

What is the cell theory?

All organisms consist of one or more cells; cells are the smallest unit of life; cells arise from other cells. Developed by Schleiden, Schwann, and Virchow.

Differences between prokaryotic and eukaryotic cells?

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both and are larger and more complex.

What is the endosymbiotic theory?

Mitochondria and chloroplasts originated as free-living bacteria engulfed by ancestral eukaryotes. Evidence: double membranes, own DNA, divide like bacteria.

Function of the nucleus?

Stores DNA; protects genetic material; contains nucleolus where ribosomes assemble.

Rough ER vs Smooth ER?

Rough ER: ribosomes, protein synthesis.
Smooth ER: lipid synthesis, detoxification.

Golgi apparatus function?

Modifies, sorts, and packages proteins and lipids for secretion or membrane use.

Lysosomes function?

Digestive organelles that break down macromolecules, waste, and pathogens.

Cytoskeleton components?

Microtubules (cell shape, movement), microfilaments (muscle contraction), intermediate filaments (structure).

What is the plasma membrane composed of?

Golgi apparatus function?

Golgi apparatus function?

Golgi apparatus function?

What is metabolism?

All chemical reactions that sustain life.

What are metabolic pathways?

Enzyme-mediated sequences of reactions.

What affects enzyme activity?

Temperature, pH, salt, cofactors, inhibitors.

What is activation energy?

Energy required to start a reaction.

Role of enzymes?

Catalysts that lower activation energy and speed up reactions.

Competitive vs noncompetitive inhibition?

Competitive binds active site; noncompetitive binds elsewhere to change enzyme shape.

What is feedback inhibition?

End-product of pathway inhibits early step to regulate production.

What is phosphorylation?

Adding phosphate to a molecule to activate it.

Overall equation for photosynthesis?

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂

Where does photosynthesis occur?

Chloroplasts (thylakoids + stroma).

Where do light-dependent reactions occur and what do they produce?

Thylakoid membranes; produce ATP, NADPH, and O₂ by splitting water.

Where does the Calvin cycle occur and what is its purpose?

Stroma; fixes CO₂ into glucose using ATP & NADPH.

What is Rubisco and why is it important?

Main CO₂-fixing enzyme; most abundant protein on Earth; prone to photorespiration.

C3 vs C4 vs CAM plants — what problem are they solving?

Preventing water loss + photorespiration in hot/dry climates.

Role of chlorophyll a?

Primary pigment that donates electrons to the ETC.

Main purpose of cellular respiration?

Convert glucose → ATP efficiently using oxygen.

Where does most ATP form?

Electron Transport Chain (ETC) via chemiosmosis in mitochondrial inner membrane.

Why is oxygen required?

Final electron acceptor → forms water.

Glycolysis facts you must know:

Occurs in cytoplasm; no oxygen needed; makes 2 ATP + 2 NADH.

Krebs cycle purpose?

Produce NADH + FADH₂ for ETC and release CO₂.

Fermentation’s real purpose?

Regenerate NAD⁺ so glycolysis continues when O₂ is low.

Why is DNA antiparallel?

Polymerase can only add nucleotides 5’→3’, creating leading/lagging strands.

What holds the double helix together?

Hydrogen bonds between bases; phosphodiester bonds on backbone

Semi-conservative replication meaning?

One old + one new strand ensures high fidelity replication.

Key enzymes you MUST know:

Helicase (unzip), DNA polymerase (extend), Ligase (seal fragments), Primase (RNA primer).

What makes mutations harmful?

Frameshifts (insertion/deletion) alter every amino acid downstream.

What is transcription and where does it occur?

DNA → mRNA in the nucleus.

What is translation and where?

mRNA → protein at ribosomes.

What is the significance of codons?

3-base mRNA units that specify amino acids.
Redundant but not ambiguous.

What is tRNA’s job?

Carry specific amino acids using anticodons that match mRNA codons.

What happens during mRNA processing (eukaryotes only)?

Introns removed, exons joined; 5’ cap & poly-A tail added.

What causes the biggest protein change?

Nonsense mutation or early STOP codon.

What is epigenetic regulation?

Changes to DNA/histones that affect expression without changing DNA sequence.

DNA methylation effect?

Shuts genes off by tightening DNA.

Histone acetylation effect?

Turns genes on by loosening chromatin.

Role of transcription factors?

Bind promoters and enhancers to increase or decrease transcription.

What is RNA interference (RNAi)?

Small RNAs degrade mRNA → stops translation.

Why do cell types differ (muscle vs nerve)?

They express different sets of genes, NOT because DNA differs.

What happens in S phase?

DNA replicates; chromosome number stays same but chromatids double.

PMAT major events?

• Prophase: chromosomes condense
• Metaphase: align at equator
• Anaphase: sister chromatids separate
• Telophase: nuclei reform

What is cytokinesis?

Division of cytoplasm → two cells.

What causes cancer at cellular level?

Mutations in tumor suppressor genes and proto-oncogenes → uncontrolled division.

Why are checkpoints important?

Prevent division of cells with DNA damage or replication errors.

Purpose of meiosis?

Produce genetically unique haploid gametes and maintain species chromosome number.

Meiosis I vs Meiosis II?

• I: homologous pairs separate (reduction division)
• II: sister chromatids separate (like mitosis)

Where does crossing over occur?

Prophase I → Exchange of DNA between homologous chromosomes.

What increases genetic variation?

Crossing over, independent assortment, random fertilization.