Question

Go through the following statements regarding a substance which enables pollen grain to tolerate in extremely adverse conditions and choose the correct option.
I. It forms the exine of the pollen grain.
II. It is one of the resistant organic materials.
III. It contains an aperture called germ pore where it is present.
IV. It can withstand high temperatures and strong acids.
V. Still, no new enzyme has been discovered which can degrade it.
(a)All statements are correct and belong to Sporopollenin.
(b)All statements are correct and belong to lignin.
(c)Statements I, II, III and IV are correct and belong to sporopollenin.
(d)Statements I, II and IV are correct and belong to sporopollenin.

Answer 1

Hint: It is one of the most chemically inert biological polymers. It is a main component of the tough outer (exine) walls of plant spores and pollen grains. It is chemically very stable and is usually well preserved in soils and sediments. The most stable form and inactive towards enzymes.

Complete answer:
Pollen grains have a prominent two-layered wall. The hard outer layer is the exine which is made up of sporopollenin. Sporopollenin is the main component of spores and pollen. It is the most resistant material known in the organic world. It is extremely resistant to non-oxidative chemicals, enzymes and strong chemical reagents. It is chemically stable and remains unchanged in pollen grains that are 500 million years old.
Sporopollenin remains unchanged when extant pollen grains are heated to 300°C or treated with concentrated acids and bases.
Due to sporopollenin pollen gets preserved during fossilization.
Pollen grain:
Each pollen grain contains mainly 2 types of cells and they are vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell. In flowering plants the vegetative tube cell produces the pollen tube, and the generative cell divides to form the two sperm cells.

      

So, the correct answer is,” All statements are correct and belong to Sporopollenin.”

Note: -No enzyme that degrades sporopollenin is so far known. Sporopollenin is also found in the spores of Bryophytes, Pteridophytes, pollen of Gymnosperms and Angiosperms.
-The function of sporopollenin is to protect the pollen grains from external damages such as rain, high temp.