Question

Assertion: The Pacific salmon fishes reproduce once in their lifetime.
Reason: Organisms evolve to adopt the most efficient strategy for reproduction.

• A. Both assertion and reason are true and the reason is the correct explanation of the assertion
• B. Both assertion and reason are true but the reason is not the correct explanation of the assertion
• C. Assertion is a true statement but the reason is false
• D. Assertion and reason are false statements

Answer 1

The correct option is A Both assertion and reason are true and the reason is the correct explanation of the assertion

Members of some species such as the Pacific salmon fish reproduce only once during their lifetime. It is born in freshwater but travels down to live in the sea or ocean water after hatching. After attaining reproductive maturity, it spends most of its energy reserves to migrate from the ocean to freshwater for reproduction. After breeding in the freshwater, the fish is not left with much energy to return back to the ocean and hence dies after a single breeding event.
In this manner, the Pacific salmon fish has evolved to attain maximum reproductive fitness i.e the ability to increase in number by reproducing fertile and healthy offsprings. This ensures steady growth of the population.

Just like the Pacific salmon fish, every organism evolves to adopt the most efficienct reproductive strategy. This can be achieved either by managing the frequency of breeding in a lifetime or by managing the number and size of the offsprings.