Question

Assertion
Pronuba moths pollinate Yucca flowers.
Reason
It has long proboscis.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion.
C. Assertion is correct, but Reason is incorrect.
D. Both Assertion and Reason are incorrect.

Answer 1

Hint: Pollination is the process of transfer of the pollen grains from the male part of a flower to the female part of the same or different flower. Reproduction of certain species of plant depends solely on pollination. Pollination can take place by wind, water or animals.

Complete answer:
Yucca belongs to family Asparagaceae. It is a perennial shrub native to parts of America and the Caribbean. The plant bears small white flowers. The morphology of the Yucca flowers is such that it does not support self-pollination. The stamens and the pistil are curved away from each. The stamen gives rise to gelatinous pollen grains that cannot be easily detached from the stamen, making it impossible to be pollinated by wind. Also, the stigma is formed in such a way that the pollen has to be inserted into it, rather than falling on the filament to reach the ovary.
These morphological features of the Yucca have led to the evolution of a unique pollination system. These species are pollinated by Yucca moths that belong to genus Pronuba. These two species share a relationship called obligate mutualism in biological terms, that is one species is completely dependent on the other for survival. The disappearance of one will eventually lead to the disappearance of the other.
The Yucca moths are small insects that lay eggs on the Yucca flowers. The females are known to collect pollen grains from the stamens of the Yucca flower with the help of their long and curved proboscis. It then flies to another flower, sits on top of the stigma and deposits pollen grains collected. Since the pollen is inserted into the stigma, fertilization is ensured. The larvae of the moths feed on the seeds of the flower. They consume only a part of the seeds, leaving enough for the plant to propagate. Once it matures, the larvae fall to the ground and pupation takes place. The adult moth emerges later. The cycle is repeated.
Hence it can be inferred that the Assertion and the reason stated in the question are correct.

Hence, the correct answer is option (A).

Note: The Yucca flower and Pronuba moths share an obligatory mutualistic relationship. These two species are dependent on each other for their survival. This is because the Yucca larvae feed on Yucca seeds, while the Yucca flowers are solely dependent on the Pronuba moths for pollination.