Question
Which processes occur in an ecosystem?
I. Biomass increases in each successive trophic level.
II. Inorganic nutrients are recycled.
III. Chemical energy is stored in carbon compounds.
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
Answer: C. II and III only
Explanation:
I. Biomass increases in each successive trophic level.
- Incorrect: As you move up each trophic level (from producers to consumers), biomass typically decreases. This happens because energy is lost as heat due to metabolic processes (as per the second law of thermodynamics), and not all of the energy in the organisms is passed to the next trophic level.
II. Inorganic nutrients are recycled.
- Correct: Inorganic nutrients like nitrogen, carbon, and phosphorus are constantly recycled in ecosystems through processes like the nitrogen cycle, carbon cycle, and phosphorus cycle. These nutrients are used by organisms, released back into the environment, and taken up again by other organisms.
III. Chemical energy is stored in carbon compounds.
- Correct: Plants capture solar energy and store it as chemical energy in carbon compounds like carbohydrates (e.g., glucose) during photosynthesis. This energy is transferred through the food chain to herbivores, carnivores, and decomposers.
Question
The three-toed sloth, Bradypus variegatus, lives in tree tops where it feeds on leaves. It also feeds on algae and fungi which live in its fur.
In which trophic group should the three-toed sloth be classified?
A. Autotroph
B. Consumer
C. Detritivore
D. Saprotroph
▶️Answer/Explanation
Answer: B. Consumer
Explanation:
The three-toed sloth is a consumer because it feeds on plants (leaves), algae, and fungi (it doesn’t produce its own food).
A. Autotroph: Autotrophs make their own food, typically through photosynthesis (e.g., plants). The sloth does not make its own food, so it is not an autotroph.
C. Detritivore: Detritivores consume dead organic matter. The sloth does not fit this classification as it feeds on live leaves and organisms in its fur.
D. Saprotroph: Saprotrophs feed on dead or decaying organic matter by secreting enzymes externally and absorbing the nutrients. Sloths don’t do this.