Read the passage given below and answer the following question.
The pollen grains serve as the male gametophytes in flowering plants. Upon touching the opened anthers of flowers like Hibiscus, one can observe the deposition of yellowish powdery pollen grains on their fingers. When these grains are sprinkled on a glass slide with a drop of water and observed under a microscope, a fascinating variety of architecture, including sizes, shapes, colours, and designs, can be seen among the pollen grains from different species. Pollen grains are generally spherical and have a diameter ranging from 25 to 50 micrometers. They possess a two-layered wall, with the outer layer composed of sporopollenin, which exhibits intricate patterns and designs. The inner wall of the pollen grain is a thin and continuous layer. When mature, the pollen grain contains two cells: the larger vegetative cell and the smaller generative cell. The vegetative cell holds abundant food reserves and a large, irregularly shaped nucleus, while the generative cell floats within the cytoplasm of the vegetative cell. In the majority of angiosperms (over 60 per cent), pollen grains are shed at the 2-celled stage, where they contain vegetative and generative cells. However, in the remaining species, the generative cell undergoes mitotic division to produce the two male gametes before the pollen grains are shed, resulting in a 3-celled stage.
In cereals such as rice and wheat, pollen grains lose their viability within how long of their release?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 30 minutes
Pollen viability is the length of time for which pollen grains stay able to germinate after release. It varies widely between species and depends partly on temperature and humidity. In cereals such as rice and wheat, pollen grains lose viability within 30 minutes of release. In some members of Rosaceae, Leguminoseae and Solanaceae, pollen stays viable for months. Pollen of many species can be stored for years in liquid nitrogen (−196°C) as pollen banks.
NCERT Extract:
Stamen, Microsporangium and Pollen Grain – “… The period for which pollen grains remain viable is highly variable and to some extent depends on the prevailing temperature and humidity. In some cereals such as rice and wheat, pollen grains lose viability within 30 minutes of their release, and in some members of Rosaceae, Leguminoseae and Solanaceae, they maintain viability for months.”