Biology Ecosystems and Energy Flow Flashcards
7 cards from real CLEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Biology Ecosystems and Energy Flow flashcards as text
In the carbon cycle, which process is responsible for transferring carbon from the atmosphere into marine organisms?
Answer: Photosynthesis by marine phytoplankton
Marine phytoplankton fix atmospheric CO₂ dissolved in seawater through photosynthesis, forming the base of marine food webs.
Eutrophication of a lake following nutrient runoff leads to fish kills primarily because:
Answer: Decomposition of dying algae depletes dissolved oxygen
Massive algal blooms die and sink; aerobic decomposition of this organic matter consumes most dissolved oxygen, creating hypoxic conditions that kill fish.
Which of the following is an example of a keystone species exerting top-down control on an ecosystem?
Answer: Sea otters limiting sea urchin populations, preserving kelp forests
Sea otters are a classic keystone predator; by controlling sea urchin numbers, they prevent overgrazing of kelp, maintaining entire kelp forest ecosystems.
In comparing aquatic and terrestrial ecosystems, which statement is generally true about energy pyramids?
Answer: In aquatic ecosystems, biomass of producers often equals or is less than that of consumers
In many aquatic ecosystems, especially open oceans, phytoplankton reproduce so rapidly that consumers (zooplankton) can maintain biomass equal to or greater than producers.
Sulfur enters the biotic component of an ecosystem primarily through:
Answer: Plant uptake of sulfate (SO₄²⁻) ions from soil solution
Plants absorb sulfate ions dissolved in soil water and incorporate sulfur into amino acids such as cysteine and methionine, entering the food web.
A researcher finds that doubling the phosphorus input to a lake doubles NPP. This suggests the lake ecosystem is:
Answer: Phosphorus-limited
If productivity responds proportionally to phosphorus additions, phosphorus is the limiting nutrient controlling primary production in that system.
Which type of symbiosis best describes the relationship between a cleaner wrasse fish and larger reef fish that it removes parasites from?
Answer: Mutualism
The cleaner wrasse gains food (parasites) while the host fish benefits from parasite removal — both organisms benefit, defining mutualism.