Florida Biology 1 EOC populations and ecosystems: a complete overview of energy flow, the cycling of matter, biomes, population dynamics, and biodiversity

What the populations and ecosystems content demands

The populations and ecosystems content completes Reporting Category 3, Organisms, Populations, and Ecosystems, the largest reporting category on the Florida Biology 1 EOC at about 40 percent. This half zooms out from the individual organism to how organisms interact with each other and their environment: how energy and matter move, how populations grow and are limited, and how humans affect it all. The recurring themes are energy and matter, systems and system models, and stability and change.

This guide ties together the matching topic pages, each with its own practice questions: energy flow and food webs, the cycling of matter, biomes and aquatic ecosystems, population dynamics and carrying capacity, and biodiversity and human impact.

Energy flow and food webs

Energy enters as sunlight, captured by producers; it flows to consumers (primary, secondary, tertiary) and is recycled by decomposers. Food-chain arrows point the way energy flows (from the eaten to the eater). At each trophic level, only about 10 percent of energy passes on (the ten percent rule); the rest is used for life processes and lost as heat, which is why an energy pyramid narrows and food chains are short.

The cycling of matter

Matter cycles while energy flows. The carbon cycle runs on photosynthesis (carbon in) and respiration (carbon out). The nitrogen cycle depends on nitrogen-fixing bacteria that convert unusable nitrogen gas into compounds plants can absorb. The water cycle moves water by evaporation, condensation, precipitation, and runoff. Decomposers recycle nutrients in all of these.

Biomes and aquatic systems

A biome is defined mainly by climate (temperature and rainfall), which sets the organisms it supports. Aquatic life depends on light, depth, temperature, and salinity. Ecology is organized as organism, population, community, ecosystem, biome, biosphere. Ecological succession is the gradual change in a community: primary (from bare rock) and secondary (after a disturbance, with soil remaining).

Population dynamics

Population size changes through births and immigration (add) and deaths and emigration (remove). Limiting factors (density-dependent like food and disease; density-independent like weather) set the carrying capacity, the maximum population an environment can support. Populations often show logistic (S-shaped) growth, leveling off at the carrying capacity.

Biodiversity and human impact

Biodiversity makes ecosystems stable and resilient and provides resources and services. It is lost through habitat destruction, pollution, climate change, overharvesting, and invasive species (like the Everglades python). Sustainability, using resources without depleting them and protecting habitats, maintains biodiversity for the future.

Check your knowledge

A mix of recall and reasoning questions covering populations and ecosystems. Attempt them under timed conditions, then check against the solutions.

1. Define producer, consumer, and decomposer. (3 marks)
2. Explain why there is less energy available at each higher trophic level. (2 marks)
3. Name the two processes that cycle carbon between living things and the atmosphere. (2 marks)
4. Explain the role of nitrogen-fixing bacteria. (2 marks)
5. State the two main abiotic factors that determine a biome. (2 marks)
6. State the difference between primary and secondary succession. (2 marks)
7. State the four processes that change population size and whether each adds or removes individuals. (2 marks)
8. Define carrying capacity. (1 mark)
9. Explain how an invasive species can reduce biodiversity. (2 marks)