Q.Which of the following reproduces once in a lifetime?

Pacific salmon and bamboo are classic semelparous organisms that breed once and then die.

Organisms differ in how often they reproduce during their life span:

• SEMELPARITY (big-bang reproduction): reproduce only once, investing everything in a single massive breeding event, then die. Examples given in NCERT are the Pacific salmon fish and bamboo species (which flower once, set seed, and die). …

Insects are classic r-selected species: they reproduce rapidly, produce many offspring, and rely on numbers rather than parental investment.

Ecologists classify life-history strategies along an r-K continuum. r-selected species thrive in unstable/unpredictable environments by maximising their intrinsic rate of increase (r): they are typically small, short-lived, mature quickly, and produce numerous offspring with minimal parental care, so population size fluctuates but numbers can rebound fast -- insects are a textbook example. K-selected species, by contrast, live in relatively stable environments near carrying capacity (K): they are typically lar …