Hint Pollen grain is transferred from one flower to another through pollinating agencies for pollination. It is first formed as unicellular with dense uninuclear cytoplasm and later it becomes 2-3 cells. The 2-3 celled pollen consists of the vegetative and generative cells.
Pollen grain represents male reproductive gametophyte which forms inside anther. The anther is the knob-like fertile, bilobed part of stamen attached at the tip of the filament. Anther lobe consists of two long parallelly arranged microsporangia. Inside the microsporangia, there are microspores which are formed which transform into pollen grains, and microsporangia transformed into pollen sacs. Microsporangium runs parallel to the side of anther lobe and consists of two parts, microsporangium wall, and sporogenous tissue. Microsporangium wall consists of the outer small and thin-walled epidermis, fibrous cellulosic wall endothecium, thin 1-3 layered wall of the middle layer, and inner nourishing layer tapetum. Sporogenous tissue found inside the microsporangium divides regularly to form microspore mother cells and microspore differentiate to form pollen grains.
The pollen grain is covered by a two-layer sporoderm. Sporoderm consists of inner intine and outer exine. Intine is made up of cellulose and pectin with the presence of some enzymatic protein. The exine is made of sporopollenin which is alkaline and highly resistant to biochemical. Sporopollenin is related to cutin and suberin which are formed by oxidative polymerization. Exine surface is pitted where sporopollenin is absent due to the presence of germ pores. Germ pore helps in the passage of male gamete toward embryo sac.
So, the correct answer is ‘Anther’.
Note: Pollen products are used as food supplements and creams. The pollen grain is abundant in nutrients like proteins, carbohydrates, and fats. It helps to increase performance in athletes. Pollen cream protects the skin from ultraviolet rays due to the presence of unsaturated fats.