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.
Which one of the following statements about pollen grains is incorrect?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Parthenium or carrot grass, which causes pollen allergy, came into India as a contaminant with imported rice.
The passage describes the structure of the pollen grain, but it says nothing about how pollen affects people. Pollen grains matter to humans in two ways: the pollen of many species causes allergies, and pollen is rich in nutrients, so it is sold as food supplements.
Option (1) Pollen grains of many species cause severe allergies and bronchial afflictions in some people, often leading to chronic respiratory disorders. — A correct statement. The pollen of many species can cause asthma, bronchitis and other chronic respiratory disorders in some people.
Option (2) Parthenium or carrot grass, which causes pollen allergy, came into India as a contaminant with imported rice. — The incorrect statement. The crop is wrong. Parthenium came into India as a contaminant with imported wheat, not rice. It has now spread everywhere and its pollen causes allergy.
Option (3) Pollen grains are rich in nutrients, and pollen tablets are used as food supplements. — A correct statement. Because pollen is rich in nutrients, pollen tablets and syrups are sold as food supplements, especially in western countries.
Option (4) Pollen consumption has been claimed to increase the performance of athletes and race horses. — A correct statement. The book mentions this claim about pollen products for athletes and race horses.
NCERT Extract:
Stamen, Microsporangium and Pollen Grain – “… Pollen grains of many species cause severe allergies and bronchial afflictions in some people often leading to chronic respiratory disorders– asthma, bronchitis, etc. It may be mentioned that Parthenium or carrot grass that came into India as a contaminant with imported wheat, has become ubiquitous in occurrence and causes pollen allergy. Pollen grains are rich in nutrients. It has become a fashion in recent years to use pollen tablets as food supplements. In western countries, a large number of pollen products in the form of tablets and syrups are available in the market. Pollen consumption has been claimed to increase the performance of athletes and race horses (Figure 1.6).”