Question

Assertion :Only red algae are able to flourish at the great depth of sea. Reason: Red algae has the pigments r-phycoerythrin and b-phycocyanin.

• A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
• B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
• C. If the assertion is true but the reason is false
• D. If both the assertion and reason are false

Answer 1

The correct option is A If both the assertion and the reason are true and the reason is a correct explanation of the assertion

The red algae flourish and occur in abundance at great depths of sea where other plants do not occur in abundance. The sunlight as it penetrates water, portions of spectrum such as red, orange yellow and green light rays which are of short wavelengths are filtered out. Only the blue and violet rays of great wavelength remain and penetrate to great depths. The green pigment chlorophyll cannot trap these light rays of great wavelength and the green plants are thus unable to carry on photosynthesis at these depth. On the other hand the red pigment r - phycoerythrin and a blue pigment b -phycocyanin which are characteristic pigments of all the red algae, can utilize wavelengths of light (blue and violet rays) not absorbed by chlorophyll So, the correct answer is 'If both the assertion and the reason are true and the reason is a correct explanation of the assertion'