Plant Pathology - Study Mode
[#281] How many pollen mother cells will form 1000 pollen grains
Correct Answer
(B) 250
Explanation
Solution: 250 pollen mother cells will form 1000 pollen grains. One diploid microspore mother cells by meiosis form 4 tetrads of haploid microspores which become 4 pollen grains. Thus, 250 pollen mother cells will produce 1000 pollen grains, by undergoing 50 rounds of meiosis.
[#282] Cellular totipotency was demonstrated by
Correct Answer
(C) F. C. Steward
Explanation
Solution: Cellular totipotency was demonstrated by F. C. Steward. Cellular totipotency is the inherent potentiality of a plant cell to give rise to a whole plant, a capacity that is retained even after a cell has undergone final differentiation in the plant body. The more cell types a cell can differentiate into, the greater its potency. Steward conducted experiments on carrot root tissues and was the first to demonstrate totipotency.
[#283] Which of the following nutrient elements is not a micronutrient?
Correct Answer
(C) S
Explanation
Solution: Sulphur is a nutrient element that is not a micronutrient. There are about seven nutrients essential to plant growth and health that are only needed in very small quantities. Sulphur is a macro element in plant nutrition. Elemental Sulphur is available to plants. Oxides are converted to sulphates along with Sulphur. It is essential for many growth functions in plants including nitrogen metabolism, enzyme activity, and protein and oil synthesis.
[#284] Nitrogen absorbed by plants is
Correct Answer
(A) Reduced to ammonia
Explanation
Solution: Nitrogen absorbed by plants is reduced to ammonia. Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi, and certain bacteria that can fix nitrogen gas (N 2 ) depend on the ability to assimilate nitrate or ammonia for their needs. Plants absorb nitrogen from the soil in the form of nitrate (NO 3 - ) and ammonium (NH 4 + ). In aerobic soils where nitrification can occur, nitrate is usually the predominant form of available nitrogen that is absorbed.
[#285] Efficiency of urea can be increased by
Correct Answer
(B) Using neem cake
Explanation
Solution: The efficiency of urea can be increased by using neem cake. Nitrification inhibitors like neem cake when applied along with urea reduce losses of applied nitrogen, thereby resulting in an improved yield of crops. The efficiency of the nutrient may be improved by combining the use of organic neem cake with the inorganic source of nitrogen fertilizer namely urea.