Chp 42: Ecosystems & Energy

The gas carbon dioxide (CO₂) is an _____.

input to photosynthesis and and product of cellular respiration.

When an organism breaks down organic molecules, some of the energy that had been stored as chemical energy is lost as heat. This happens because

Every energy transfer/transformation increases entropy

On a global scale, energy _____ ecosystems whereas chemical elements _____ ecosystems.

flows through ... are recycled in

The energy for nearly every organism in nearly every ecosystem ultimately comes from _____.

the sun

Consider this segment of a food web: Snails and grasshoppers eat pepper plants; spiders eat grasshoppers; shrews eat snails and spiders; owls eat shrews. The shrew occupies the trophic level(s) of _____.

secondary + tertiary

The relationship between biomass and primary productivity is that _____.

primary productivity is the rate at which biomass is produced

Which of the following equations is correct?

NPP = GPP −

R

_a

Which of these ecosystems has the LOWEST net primary production per square meter?

open ocean

Why is a diagram of energy flow from trophic level to trophic level shaped like a pyramid?

Most energy at each level is lost, leaving little for the next.

____ are secondary consumers.

Carnivores

Approximately _____% of the energy at one trophic level is passed on to the next highest trophic level.

5-10%

10,000 kcal of producer could support approximately _____ kcal of tertiary consumer.

10

Biogeochemical cycles are crucial to ecosystem function because _____.

nutrients and other life-sustaining molecules are in limited supply and must be continually recycled.

What name is given to the process by which detritivores return carbon to the atmosphere?

Decomposition

Which of these removes carbon from the atmosphere?

Algae

Detritus is composed of _____.

dead organic matter + excreted waste.

What role do nitrifying bacteria play in ecosystems?

convert ammonium to nitrates

Which of the following processes removes nitrogen gas

(N

₂

)

from the atmosphere?

nitrogen fixation

What role do denitrifying bacteria play in ecosystems?

convert nitrates to nitrogen gas

Which one of these is a nitrate?

NO3-

Which one of these is a nitrite?

NO2-

An ecosystem is unlikely to be limited by the supply of _____ because it is obtained from the air.

carbon

Nitrifying bacteria participate in the nitrogen cycle mainly by __________.

converting ammonium to nitrate, which plants absorb

Which of the following was a result of the Hubbard Brook watershed deforestation experiment?

The nitrate concentration in waters draining the deforested area became dangerously high.

The discipline that applies ecological principles to returning degraded ecosystems to a more natural state is known as __________.

restoration ecology

Which of the following are

density-dependent

factors that could account for the population decreases at various timepoints in the graph? Select all that apply.

→ territoriality

→ disease

Which of the following organisms in the arctic tundra ecosystem retains the

least

chemical energy fixed by photosynthesis?

artic fox