Which of the following best describes the difference between saprotrophs and detritivores in an ecosystem?

• A. Saprotrophs externally digest dead organic matter and absorb nutrients, while detritivores ingest and internally digest dead organic matter.
• B. Both saprotrophs and detritivores photosynthesize to obtain energy from sunlight.
• C. Detritivores produce their own food through chemosynthesis, while saprotrophs rely on consuming living organisms.
• D. Saprotrophs and detritivores are both primary producers in the food chain.

Answer: (A)

Verified step by step guidance

1. Understand the definitions of saprotrophs and detritivores: Saprotrophs are organisms, such as fungi and some bacteria, that externally digest dead organic matter by secreting enzymes and then absorb the resulting nutrients. Detritivores, on the other hand, are organisms, such as earthworms and some insects, that ingest dead organic matter and internally digest it to obtain nutrients.
2. Analyze the first option: 'Saprotrophs externally digest dead organic matter and absorb nutrients, while detritivores ingest and internally digest dead organic matter.' This aligns with the definitions of saprotrophs and detritivores, so it is a strong candidate for the correct answer.
3. Evaluate the second option: 'Both saprotrophs and detritivores photosynthesize to obtain energy from sunlight.' This is incorrect because neither saprotrophs nor detritivores photosynthesize; photosynthesis is a process performed by autotrophs, such as plants and algae.
4. Evaluate the third option: 'Detritivores produce their own food through chemosynthesis, while saprotrophs rely on consuming living organisms.' This is incorrect because detritivores do not produce their own food through chemosynthesis, and saprotrophs consume dead, not living, organic matter.
5. Evaluate the fourth option: 'Saprotrophs and detritivores are both primary producers in the food chain.' This is incorrect because primary producers are autotrophs that produce their own food (e.g., through photosynthesis or chemosynthesis), while saprotrophs and detritivores are decomposers that break down dead organic matter.