AP Bio Ch. 42 - Ecosystems and Energy

Flashcards covering key terms and concepts from the lecture on ecosystems and energy.

Ecosystem

A community of living organisms interacting with their abiotic environment.

Energy flow in ecosystems

Energy enters ecosystems as solar energy, is converted to chemical energy by producers, and exits as heat energy.

Producers

Organisms that capture solar energy and convert it into chemical energy through photosynthesis or chemosynthesis; they support all other trophic levels.

Photosynthetic Autotrophs

Organisms that produce their own food using light energy; examples include plants, algae, and photosynthetic bacteria.

Chemosynthetic Bacteria

Primary producers found in deep-sea vents that convert inorganic compounds into organic material in the absence of sunlight.

Trophic Levels

The hierarchical levels in an ecosystem, where producers are at the first level and consumers follow in successive levels.

Detritivores

Organisms that consume non-living organic matter; examples include dung beetles, earthworms, and maggots.

Primary Production

The amount of light energy converted to chemical energy by autotrophs during a specific time period.

Gross Primary Production (GPP)

The total amount of chemical energy produced by autotrophs in a given time. # of calories made.

Net Primary Production (NPP)

The energy left over for other trophies levels; calculated as:

ALSO: amount of new biomass added in a given period of time.

NPP = GPP - Cellular Respiration of Autotrophs

Why is NET PP a key measurement to ecologists?

Allows them to see the amount of energy left for other trophic levels.

Why does a tropical rain forest have a greater biomass/unit area and higher net primary production?

Because lots of sunlight is absorbed by vegetation.

Limiting factors of primary productivity in aquatic ecosystems

Light - Can’t travel far down

Nitrogen and Phosphorus

Limiting Nutrient

Not enough of essential substance which hinders growth of organisms.

Ex: Nitrogen and Phosphorus of shore of NY, and Iron in Sargasso Sea

Fertilizer

Allows growth of Phytoplankton, has lots of nitrates and phosphates.

Eutrophication

Sudden influx of nutrients that encourages algae to grow which blocks sunlight from deeper waters and lowers oxygen levels.

Trophic efficiency

Percentage of production transferred from one trophic level to the next

10% Rule

Percentage of energy available at one trophic level that is available at the next.

Ex: Start with 1000 joules at producer level (Grass), how much is found at the last level (Crow)?

Grass 1000 J → grasshopper 100 J → lizard 10 J → crow 1 J

1 Joule left.

Energy Pyramid

Greatest Biomass on the bottom

Why do people in overpopulated parts of the world tend to eat low on the food chain?

So they don’t waste energy on middle trophic levels. More energy at lower levels.