Question

(a) A bilobed dithecous anther has 200 microspore mother cells per microsporangium. How many male gametophytes can be produced by this anther?
(b) Write the composition of intine and exine layers of a pollen grain.

Hint:

Each microspore mother cell in an anther produces 4 microspores via meiosis, and each microspore develops into a single male gametophyte (pollen grain).

Answer 1

Step 1: For (a), a bilobed dithecous anther has 4 microsporangia (2 per lobe). Each microsporangium has 200 microspore mother cells (MMCs). Each MMC undergoes meiosis to produce 4 microspores, and each microspore develops into 1 male gametophyte (pollen grain). So, 200 MMCs produce 200 × 4 = 800 microspores per microsporangium. For 4 microsporangia, total microspores = 800 × 4 = 3200, which equals 3200 male gametophytes.
Step 2: For (b), the exine of a pollen grain is composed of sporopollenin, a tough, resistant polymer that protects the pollen. The intine is composed of cellulose and pectin, providing flexibility and support for pollen tube growth.
Thus, the anther produces 3200 male gametophytes, with the exine made of sporopollenin and intine made of cellulose and pectin.