02/12 02. Ecosystems, Energy Flow, and Biodiversity Free Online FlashCards

What is an ecosystem?

An ecosystem is an interconnected system in which organisms interact with one another and with abiotic factors such as sunlight, temperature, water, soil, and nutrients.

What does primary productivity measure?

Primary productivity is the rate at which primary producers convert energy into chemical energy stored in organic matter.

How is net primary productivity calculated?

NPP = GPP − producer respiration. If GPP is 20,000 kcal/m²/year and respiration is 8,000, NPP is 12,000 kcal/m²/year.

How does chemosynthesis differ from photosynthesis?

Chemosynthetic producers obtain energy by oxidizing inorganic substances such as hydrogen sulfide, rather than using sunlight. Some bacteria near deep-sea hydrothermal vents use this process.

Why are food webs more realistic than food chains?

A food web combines many interconnected food chains and more accurately represents ecosystem structure because organisms commonly have multiple food sources and predators.

What role do decomposers play?

Decomposers such as fungi and bacteria break down dead organisms and wastes from all trophic levels, releasing nutrients back into the environment.

What do arrows in a food chain represent?

Arrows point from the organism being eaten to the organism that consumes it, showing the direction of energy transfer.

What does the 10% rule describe?

The 10% rule is an approximation that about 10% of energy available at one trophic level transfers to the next. Actual transfer efficiency varies among organisms and ecosystems.

What is biomagnification?

Biomagnification is the increasing concentration of persistent pollutants at higher trophic levels, often reaching the highest concentration in top predators.

Why is an energy pyramid always upright?

An energy pyramid is always upright because available energy decreases at every trophic transfer as organisms use energy and release heat.

Why can an aquatic biomass pyramid be inverted?

An aquatic biomass pyramid may be inverted because phytoplankton have low standing biomass but reproduce rapidly and are consumed soon after reproducing.

What are the four categories of ecosystem services?

The four categories are provisioning, regulating, cultural, and supporting services. Examples include food, climate regulation, recreation, and nutrient cycling.