Question

Assertion (A): If 50,000 joules of sun’s light energy falls on the plants (producers), the energy which will be available in plant matter as food will be 500 joules. 

Reason (R): If 50,000 joules of sun’s light energy falls on the plants (producers), the energy which will be available is plant matter as food will be 5000 joules.

Options

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

A is true but R is false.

Explanation:

Only about 1% of the Sun’s light energy falling on plants is captured during photosynthesis and stored as food. Therefore, if 50,000 J of solar energy falls on plants, the energy available in plant matter as food will be:

1% of 50,000 J = 500 J

Hence, Assertion (A) is true.

The Reason states that 5,000 J of energy will be available as food, which is 10% of 50,000 J. This is incorrect because plants capture only about 1% of the Sun's light energy, not 10%. Therefore, Reason (R) is false.

Hence, A is true but R is false.