Question

Read statements (a-c) regarding pollen grains and select the option that has correct statements.
a. The generative cell floats in the cytoplasm of the vegetative cell.
b. Sporopollenin is absent at germ pores.
c. Pollen grain measures about 25-50 micrometer in diameter.

• A. a, b and c
• B. Only b and c
• C. Only a
• D. Only a and b

Answer 1

Answer: (A)

Pollen grains are generally spherical measuring about 25-50 micrometers in diameter. It has a prominent two-layered wall. The hard outer layer called the exine is made up of sporopollenin, which is one of the most resistant organic material known. It can withstand high temperatures, strong acids and alkali. No enzyme that degrades sporopollenin is so far known. Pollen grain exine has prominent apertures called germ pores where sporopollenin is absent. Pollen grains are well preserved as fossils because of the presence of sporopollenin.
The cytoplasm of the pollen grain is surrounded by a plasma membrane. When the pollen grain is mature, it contains two cells, the vegetative cell and generative cell. The vegetative cell is bigger, has abundant food reserve and a large irregularly shaped nucleus. The generative cell is small and floats in the cytoplasm of the vegetative cell.