How many of the following statements about life history variation are correct?
A. Pacific salmon fish breeds only once in its lifetime.
B. Bamboo breeds many times during its lifetime.
C. Oysters produce a large number of small-sized offspring.
D. Pelagic fishes produce a small number of large-sized offspring.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Two
Populations evolve to maximise their reproductive fitness. So organisms differ in how many times they breed in a lifetime and in the number and size of offspring they produce.
Statement A: Pacific salmon fish breeds only once in its lifetime. — True. NCERT puts Pacific salmon fish with bamboo among the organisms that breed just once.
Statement B: Bamboo breeds many times during its lifetime. — False. Bamboo, like Pacific salmon, breeds only once in its lifetime. Most birds and mammals are the ones that breed many times.
Statement C: Oysters produce a large number of small-sized offspring. — True. Oysters, along with pelagic fishes, follow the strategy of many small offspring.
Statement D: Pelagic fishes produce a small number of large-sized offspring. — False. Pelagic fishes, like oysters, produce a large number of small-sized offspring. Birds and mammals produce a small number of large-sized offspring.
Statements A and C are correct, so two statements are correct.
NCERT Extract:
Life History Variation – “… Populations evolve to maximise their reproductive fitness, also called Darwinian fitness (high r value), in the habitat in which they live. Under a particular set of selection pressures, organisms evolve towards the most efficient reproductive strategy. Some organisms breed only once in their lifetime (Pacific salmon fish, bamboo) while others breed many times during their lifetime (most birds and mammals). Some produce a large number of small-sized offspring (Oysters, pelagic fishes) while others produce a small number of large-sized offspring (birds, mammals).”