General Biology Final Exam Review: Key Concepts and Study Guide

Biology: The Study of Life

What is Biology?

• Biology is the scientific study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy.

• It seeks to understand the interactions between organisms and their environments.

Scientific Method

• The scientific method is a systematic approach to inquiry that involves observation, hypothesis formation, experimentation, and conclusion.

• Key steps: Observation > Question > Hypothesis > Experiment > Analysis > Conclusion.

The Biosphere and Ecosystems

Levels of Biological Organization

• Hierarchy: Organism > Population > Community > Ecosystem > Biosphere.

• Population: Group of individuals of the same species in a given area.

• Community: All populations of different species in a given area.

• Ecosystem: Community plus the nonliving (abiotic) environment.

• Biosphere: All ecosystems on Earth.

Abiotic vs. Biotic Factors

• Abiotic factors: Nonliving components (e.g., sunlight, temperature, water, soil).

• Biotic factors: Living components (e.g., plants, animals, bacteria).

Major Biomes

• Biomes are large ecological areas with distinct climate, flora, and fauna (e.g., tundra, desert, rainforest, grassland).

• Distribution is influenced by temperature, precipitation, and latitude.

Population Ecology

Population Growth Models

• Exponential growth: Population increases rapidly under ideal conditions (J-shaped curve).

• Logistic growth: Population growth slows as it approaches carrying capacity (S-shaped curve).

$\text{Exponential growth:}\ N_t = N_0 e^{rt}$

$\text{Logistic growth:}\ \frac{dN}{dt} = rN\left(1 - \frac{N}{K}\right)$

• Carrying capacity (K): Maximum population size an environment can sustain.

Factors Affecting Population Growth

• Density-dependent factors: Effects increase with population density (e.g., competition, predation, disease).

• Density-independent factors: Effects are unrelated to population density (e.g., weather, natural disasters).

Human Population Growth

• Human populations have shown exponential growth, but growth rates vary by region and development status.

• Demographic transition: Shift from high birth/death rates to low birth/death rates as a country develops.

Community Ecology

Species Interactions

• Competition: Two species use the same resource; both may be harmed.

• Predation: One organism (predator) feeds on another (prey).

• Mutualism: Both species benefit (e.g., bees and flowers).

• Commensalism: One benefits, the other is unaffected.

• Parasitism: One benefits (parasite), the other is harmed (host).

Ecological Niches

• Niche: The role and space an organism fills in its ecosystem, including resources used and interactions.

• Competitive exclusion principle: No two species can occupy the same niche indefinitely.

Succession

• Primary succession: Occurs in lifeless areas (e.g., after lava flow).

• Secondary succession: Occurs where a disturbance destroys a community without destroying the soil.

Energy Flow and Nutrient Cycling

Trophic Levels

• Producers (autotrophs): Make their own food (e.g., plants).

• Consumers (heterotrophs): Eat other organisms (primary, secondary, tertiary consumers).

• Decomposers: Break down dead material (e.g., bacteria, fungi).

Energy Transfer

• Energy flows through ecosystems in one direction: sun → producers → consumers → decomposers.

• Only about 10% of energy is transferred from one trophic level to the next (10% rule).

Biogeochemical Cycles

• Water cycle: Movement of water through evaporation, condensation, precipitation, and runoff.

• Carbon cycle: Movement of carbon among atmosphere, organisms, and earth (photosynthesis, respiration, decomposition).

• Nitrogen cycle: Conversion of nitrogen among various chemical forms (nitrogen fixation, nitrification, denitrification).

Conservation Biology and Human Impact

Biodiversity

• Biodiversity: Variety of life in all its forms and levels (genetic, species, ecosystem diversity).

• Threats: Habitat destruction, pollution, overexploitation, invasive species, climate change.

Sustainable Resource Management

• Sustainable management: Using resources in ways that maintain ecosystem health and productivity for future generations.

• Examples: Selective logging, crop rotation, protected areas.

Restoration Ecology

• Focuses on restoring degraded ecosystems to a more natural state.

• Methods include reforestation, removal of invasive species, and reintroduction of native species.

Additional info:

• Many questions in the file relate to population ecology, community interactions, energy flow, and conservation, which correspond to chapters 34-38 in a typical General Biology curriculum.

• Some questions also address the scientific method and basic ecological principles.