Question

Heterosis requires?
A) Selection
B) Crossing
C)Transformation
D) Mutation

Answer 1

Hint


Complete Step-by-step answer:

Heterosis requires crossing between the plants. It is lost in the plants that are self-pollinated in the F2 generation and decreases slowly in the plants which are cross-pollinated. So it is more advantageous in plants that are propagated vegetatively because these plants do not involve sexual reproduction so hybrid vigor is not lost in these crops, for example, sweet potato, sugarcane, strawberry, grapes, etc.

The majority of flowering plants produce hermaphrodite flowers and pollen grains are likely to come in contact with the stigma of the same flower. Continued self-pollination leads to inbreeding depression. Flowers have developed many devices to discourage self-pollination i.e., production of unisexual flowers, self-incompatibility, release to stigma, and pollen not synchronized. 

Selection is the process in which germplasm is evaluated to identify plants with a desirable combination of characteristics. Mutation is a process by which genetic variations are created through changes in the base sequence within genes resulting in the creation of a new character or trait not found in the parental type. Transformation is the process in which genetic material i.e., in form of deoxyribonucleic acid(DNA) is transferred between microbial cells.

Hence the correct answer is option B i.e., Heterosis.

Note: The term heterosis was first coined by Shull in 1914. And in some cases, the hybrid may be inferior to the weaker parent and this is also regarded as heterosis.