question_answer

(i) 'The coevolution of the flower and its pollinator species is linked with one another.? Comment.

(ii) What are the different categories of flowers pollinated by animals?

Or

Describe the functions of the following

(i) Epididymis

(ii) Vas deferens

(iii) Seminiferous tubules

(iv) Vagina

(v) Trophoblast

Answer:

(i) Coevolution is the evolution in two species that interact extensively with one another so that each acts as amajor source of natural selection on the other. The coevolution of the flower and its pollinator species is tightly linked with one another. Flower parts are modified, shaped by mutations and undergo natural selection into a form that enhances pollination. Majority of insect pollinated flowers are beautifully coloured, fragrant, rich in nectar, large in size or when small grouped into an inflorescence to make them conspicuous. To sustain animal visits, flowers have to provide rewards to the animals. Nectar, pollen grains, shelter and edible floral parts and young seeds are the usual floral rewards for pollinators. They also get juicy and nutritious fruits so that insects/animals regularly visit them to feed or take shelter. For harvesting the rewards from the flower, the animal visitor comes in contact with the anthers and the stigma of the flower. The sticky pollens of insect pollinated flowers get adhered to the body of pollinator. When this pollinator carrying pollen on its body comes in contact with the stigma, it brings about pollination.

(ii) Flowers pollinated by animals can be grouped into two categories depending upon the benefits (rewards) which they provide to the pollinators.

(a) Food providing flowers (e.g. Salvia and bees, hummingbirds and Begonia, sun birds and Strelitzia).

(b) Nursery providing flower (e.g. Yucca and Yucca moth and wasp).

Or

Functions of the following are as follows

(i) Epididymis It stores sperms and also secretes a fluid which is considered to nourish the sperms.

(ii) Vas deferens It stores and transports the sperms from the testes to the outside through urethra.

(iii) Seminiferous tubules Sperms are produced here by the process of spermatogenesis.

(iv) Vagina It receives the semen from the male penis. It serves as the birth canal during parturition.

(v) Trophoblast It is the inner layer of blastocyst, which sends finger - like projections called chorionic villi into uterine stroma. Chorionic villi and uterine tissues jointly form the placenta.