Question

Assertion- Red algae contribute in producing coral reefs.
Reason- Some red algae secrete and deposit calcium carbonate over their walls.
a) Both assertion and reason are correct and reason is the correct explanation for the assertion.
b) Both assertion and reason are correct but reason is not the correct explanation for the assertion.
c)Assertion is correct but the reason is incorrect.
d)Both assertion and reason are incorrect.

Answer 1

Red algae are the largest phylum of the algae. They are eukaryotic in nature. They lack complex membrane bound organelles in their cell structure. Phycobiliproteins give them their characteristic color of red. They are usually found in the coral reefs.

Complete answer:
Red algae consist of coralline algae which is responsible for the production of the coral reefs. They have thallus which is hard due to the presence of the calcareous deposits present on their cell wall. They impart pink and some shades of red color to the coral reef. They play an important role in the ecology of the coral reefs. Sea urchins and parrotfish and some molluscs feed on the coralline algae. In the Mediterranean Sea, the coral reefs found are mainly made up of the red algae. When we take a close look at the coral reefs, we can notice the abundance of the pinkish patches present all over the rock. These patches are living red algae or we can say that they are coralline red algae. These algae contain calcium carbonate which helps them to fossilize really well. They also contain magnesium deposition on them. The coral reefs are formed through the deposition and accumulation of the calcium-containing exoskeleton of the sea animals. The red algae also contain calcium deposition. These depositions are the foundation of the reefs. They provide protection to the coral polyps living in the reefs.
So, the answer is ‘both assertion and reason are correct and the reason is the correct explanation for the assertion’.

Note: Coral reefs are the ecosystem present underwater. They are formed with the help of coral polyps which are held together by the calcium deposition of the algae or the dead sea animals. They are an essential part of the ecosystem as some fishes reside in them.