Question

Regarding the assertion and reason, choose the correct option:
Assertion [A]: Of the three major types of algae that exist underwater, red algae are found at the deepest range.
Reason [R]: The accessory pigment of red algae phycobilin can take in blue light.

• A. Both A and R are correct and R explains A
• B. Both A and R are correct but R does not explain A
• C. A is incorrect but R is correct
• D. Both A and R are incorrect

Answer 1

The correct option is A Both A and R are correct and R explains A

Green algae, red algae and brown algae are the three major types of algae found underwater. Of the colours of visible spectrum that penetrate water, blue penetrates the most, reaching as low as 300 meters; green and violet reach around 100 meters, while red is the poorest. Green algae possess chlorophylls, which mainly absorb blue and red light, and appear green. Brown algae contain the pigment fucoxanthin, which absorbs blue-green and yellow-green light and appear brown. Red algae contain phycobilins, which primarily absorb blue light and appear red. Thus, red algae are found deepest, green algae at the uppermost layers, and brown algae intermediate between these.