Question

Explain the role of decomposers in oxygen stratification.

1. Decomposers increase oxygen levels by breaking down organic matter.
2. Decomposers consume oxygen, leading to lower concentrations at the bottom.
3. Decomposers are primarily found in the well-lighted surface layer.
4. The activity of decomposers is independent of oxygen levels.

• A. i only
• B. iv only
• C. ii only
• D. All

Answer 1

Answer:

C. ii only

• The surface layer has the maximum oxygen content due to two main reasons.

• Being well lighted, maximum photosynthetic oxygen is produced here.

• Being in intimate contact with the atmosphere, it permits free diffusion of oxygen into it from the air.

• The oxygen content, beneath the surface water decreases, as both these oxygen sources disappear.

• At the bottom the oxygen content decreases further due to utilisation of oxygen by decomposers occurring here.