Biology Exam 4 Final Study Guide

What is energy balance?

Comparison of energy intake vs. energy expenditure.

When is weight stable?

When energy intake = energy expenditure.

What causes weight gain?

Energy intake > energy expenditure.

What causes weight loss?

Energy intake < energy expenditure.

What is the absorptive state?

State during/after eating when nutrients enter the bloodstream.

What increases after a carb‑rich meal?

Blood glucose and insulin.

What are the goals of the absorptive state?

Use incoming nutrients; store extra energy.

What is the postabsorptive state?

State between meals when stored energy is used.

Hormone levels in postabsorptive state?

Insulin ↓, glucagon ↑.

What is glycogenolysis?

Breakdown of glycogen into glucose.

What is gluconeogenesis?

Formation of glucose from non‑carbohydrate sources.

What is glucose sparing?

Cells use fatty acids instead of glucose to preserve glucose for the brain.

What does insulin do?

Lowers blood glucose; increases uptake; promotes storage.

What does glucagon do?

Raises blood glucose; stimulates glycogen breakdown & gluconeogenesis.

Why are insulin and glucagon antagonistic?

They have opposite effects on blood glucose.

How does exercise affect metabolism?

Increases ATP demand, oxygen use, and fuel use.

Hormone changes during exercise?

Insulin ↓, glucagon ↑, epinephrine ↑.

What is metabolic rate?

Total energy used over time.

Why does muscle increase metabolic rate?

Muscle uses more energy than fat at rest.

What are ectotherms?

Animals relying on external heat sources.

What are endotherms?

Animals generating internal heat.

Windy‑day heat loss is due to what?

Convection.

What are pathogens?

Disease‑causing organisms or agents.

Major pathogen types?

Bacteria, viruses, eukaryotic parasites.

How do bacteria harm hosts?

Tissue damage; toxin release.

What is unique about viruses?

Replicate only inside host cells.

Examples of eukaryotic parasites?

Protists, fungi, helminths.

What is innate immunity?

Fast, nonspecific, present at birth.

What is adaptive immunity?

Specific, slower first exposure, has memory.

What is phagocytosis?

Engulfing and digesting pathogens.

Phagocytic cells?

Neutrophils and macrophages.

What triggers inflammation?

Injury or infection.

What releases histamine?

Mast cells.

What does histamine do?

Increases blood flow to damaged area.

Signs of inflammation?

Redness, heat, swelling, pain.

What do TLRs recognize?

Common pathogen molecules.

What do B cells do?

Produce antibodies (humoral immunity).

What do cytotoxic T cells do?

Kill infected body cells.

What do helper T cells do?

Activate other immune cells.

How does vaccination work?

Exposes antigen → forms memory cells.

How does HIV weaken immunity?

Infects helper T cells.

What is ecology?

Study of interactions between organisms and environment.

Biotic factors?

Living components.

Abiotic factors?

Nonliving components.

What is an ecosystem?

A community + its physical environment.

What is energy flow?

Sun → producers → consumers → decomposers.

Why does energy decrease at each trophic level?

Lost as heat.

What determines terrestrial biomes?

Temperature and rainfall.

High temp + high rainfall biome?

Tropical rainforest.

Very low rainfall biome?

Desert.

Why is the equator warmer?

Receives more direct sunlight.

What is a rain shadow?

Dry area behind mountains blocking moist air.

What is behavior?

Observable response to stimuli.

What does behavioral ecology study?

How behavior affects fitness, survival, reproduction.

Proximate causes?

How a behavior happens.

Ultimate causes?

Why a behavior evolved.

Innate behavior?

Inborn, genetically determined.

Fixed action pattern?

Triggered by sign stimulus; runs to completion.

Habituation?

Decreased response to repeated stimulus.

Classical conditioning?

Association between stimuli.

Operant conditioning?

Behavior shaped by rewards/punishments.

Imprinting?

Rapid, irreversible learning during critical period.

Kinesis?

Random movement influenced by stimulus intensity.

Taxis?

Directed movement toward/away from stimulus.

Migration?

Long‑distance seasonal movement.

Optimal foraging theory?

Maximize energy gained; minimize costs.

Benefits of group living?

Reduced predation, better food detection, cooperative care.

Costs of group living?

Competition, disease, resource depletion.

Altruism?

Behavior benefiting another at a cost to the actor.

Kin selection?

Helping relatives increases shared genes.

Inclusive fitness?

Direct + indirect fitness.

Sexual selection?

Traits improving mating success.