Question

Ultimate source of energy for living beings is

• A.
  Fats
• B.
  Sunlight
• C.
  ATP
• D.
  Carbohydrates

Answer 1

The correct option is B

Sunlight
Carbohydrates
Carbohydrates in the body serve as fuel for the generation of energy that can be used to drive all the metabolic functions of the body. Producers can prepare their own carbohydrates using solar energy or chemical energy. Consumers obtain carbohydrates by feeding on other organisms. Thus, carbohydrates cannot be considered the ultimate source of energy as their formation in producers requires an input of external energy.

Fats
Fats present in the food that we eat can provide us with energy but fats are not the ultimate source of energy as fats are broken down to generate energy only during starvation periods.

Sunlight
For any ecosystem to function and sustain, the basic requirement is a constant input of solar energy. Solar energy obtained from sunlight is the ultimate source of energy required for the production of food through the process of photosynthesis by the producers. This helps to maintain energy flow in the ecosystem through the food chain as producers are the ultimate sources of food for all living beings on earth. Decomposers tap this energy when they feed on dead remains of organisms.

ATP
ATP is a chemical compound that is considered as the energy currency of a cell. The cellular breakdown of carbohydrates and fats in the cells during respiration generates ATP molecules which can be used by the cell as an energy currency to drive metabolic reactions.

Final answer
c. Sunlight