Biology Ecosystems and Energy Flow Flashcards

Which ecological term describes the total mass of living organisms in a given area at a given time?

Answer: Biomass

Biomass refers to the total mass of living organic matter in an ecosystem or trophic level.

In a food web, detritivores play which role?

Answer: They feed on dead organic matter and break it into smaller pieces

Detritivores such as earthworms and millipedes consume dead organic material, physically breaking it down before decomposers chemically process it.

Gross Primary Productivity (GPP) minus plant respiration equals:

Answer: Net Primary Productivity (NPP)

Net Primary Productivity (NPP) is the energy available to consumers after plants use some GPP for their own cellular respiration.

Which biome stores the greatest amount of carbon per unit area in above-ground plant biomass?

Answer: Tropical rainforest

Tropical rainforests have the highest above-ground plant biomass and therefore store more carbon per unit area than any other terrestrial biome.

The 'green world hypothesis' suggests that herbivore populations are kept in check primarily by:

Answer: Predation and disease

The green world hypothesis proposes that top-down control by predators and parasites prevents herbivores from consuming all available plant material.

In an upwelling zone in the ocean, nutrients from deep water rise to the surface. This primarily increases which trophic level most directly?

Answer: Primary producers (phytoplankton)

Nutrients like nitrates and phosphates from upwelling directly fuel phytoplankton (primary producer) growth, which then supports higher trophic levels.

Which process in the nitrogen cycle converts nitrates (NO₃⁻) back into atmospheric nitrogen gas (N₂)?

Answer: Denitrification

Denitrification, carried out by anaerobic bacteria in waterlogged soils, converts nitrates back into N₂ gas, completing the nitrogen cycle.