Question

in an ecosystem, which organisms convert sunlight into energy - rich organic compounds?
a. decomposers
b. primary producers
c. tertiary consumers
d. consumers
what happens when a keystone species is removed from an ecosystem?
a. increased population of primary producers
b. disruption of ecosystem balance
c. no impact on the ecosystem
d. decreased biodiversity
what role do herbivores play in an ecosystem
a. they are primary producers
b. they are secondary consumers
c. they decompose organic matter
d. they feed exclusively on plants
what role do decomposers play in an ecosystem?
a. they are top predators.
b. they are primary producers.
c. they break down dead organic matter.
d. they feed on primary consumers.

Explanation:

• First question: Primary producers (like plants) perform photosynthesis to convert sunlight into energy - rich organic compounds (glucose). Decomposers break down dead matter, consumers (including tertiary consumers) consume other organisms for energy.
• Second question: Keystone species have a disproportionately large impact on their ecosystem relative to their abundance. Removing them disrupts the ecosystem balance. While decreased biodiversity can be a consequence, the most direct and over - arching effect is the disruption of balance. An increase in primary producers is not the main effect, and there is definitely an impact on the ecosystem.
• Third question: Herbivores are primary consumers as they feed exclusively on plants (primary producers). They are not primary producers (which make their own food), not secondary consumers (which eat primary consumers), and do not decompose organic matter (that's the role of decomposers).
• Fourth question: Decomposers (like fungi and bacteria) break down dead organic matter. They are not top predators (which are tertiary or higher - level consumers), not primary producers (which make their own food), and do not feed on primary consumers (that's the role of secondary consumers).

Answer:

1. B. Primary producers
2. B. Disruption of ecosystem balance
3. D. They feed exclusively on plants
4. C. They break down dead organic matter