Question

A food chain starts with

• A. Nitrogen fixation organisms
• B. Photosynthesizing organisms
• C. Respiration
• D. Decomposers

Answer 1

The correct option is B

Photosynthesizing organisms

The correct option is B

Explanation of the correct option:

Food chain:

1. The food chain is the sequence of eating and being eaten in a natural environment.
2. A food chain consists of producers, consumers as well as decomposers.
3. In the food chain plants (photosynthesizing organisms) are the producers as they prepare their own food and they are present at the base of the trophic level.
4. Animals are the consumers, as they feed upon the plants.
5. Bacteria and fungi are the decomposers, as they feed on the dead, decay, and other remaining of living organisms.

Explanation of the incorrect option:

Option A:

1. Nitrogen-fixing bacteria find their own source of energy, typically by oxidizing organic molecules released by other organisms or from decomposition.
2. They do not produce food for others.

Option C:

Respiration is an event that transforms the energy stored in foods eaten by an organism into energy that can be used for metabolic processes that sustain the organism's life.

Option D:

Decomposers complete the cycle by returning nutrients to the soil or oceans for use by autotrophs which then initiate a whole new food chain.

Final answer: A food chain starts with photosynthesizing organisms.