Genetics And Plant Breeding - Study Mode
[#376] Consider the following statements Hybrid seed production process induces 1. production of inbreed lines 2. selection of inbreed lines 3. production of F 1 seed. 4. testing of combining ability Select the correct answer:
Correct Answer
(C) 1, 2, 4 and 3
Explanation
Solution: The correct sequence of hybrid seed production is 1, 2, 4 and 3 respectively. Hybrid seed is produced by cross-pollinated plants. Hybrid seed production is predominant in modern agriculture and home gardening. Crossing two genetically different plants produce a hybrid seed (plant) using controlled pollination. To produce consistent F 1 hybrids, the original cross must be repeated for each season. The hybrid seed production process induces the production of inbreed lines, selection of inbreed lines, testing of combining ability and lastly production of F 1 seed.
[#377] Theory of 'Gemmules' was proposed by
Correct Answer
(A) Darwin
Explanation
Solution: The theory of 'Gemmules' was proposed by Darwin. In 1868 Charles Darwin proposed Pangenesis, a developmental theory of heredity. He suggested that all cells in an organism are capable of shedding minute particles he called gemmules, which can circulate throughout the body and finally congregate in the gonads.
[#378] The Pebble mill is used
Correct Answer
(B) To remove the webby hairs from grasses
Explanation
Solution: The Pebble mill is used to remove the webby hairs from grasses. The mill is used for removing cob-webby hairs from bluegrass and similar seeds. It has a drum rotating about a shaft, inserted off-centre at opposite ends. The mill is loaded with seeds and smooth half-inch pebbles and turned at a slow speed until the rubbing action of the pebble rolls the fuzz from the seeds into small round balls.
[#379] How many linkage group are present in a plant 2n = 24?
Correct Answer
(C) 12
Explanation
Solution: The number of linkage groups in diploid plants with chromosome number 24 will be 12. $$left( {frac{{24}}{2} = 12}
ight).$$ Linkage, as related to genetics and genomics, refers to the closeness of genes or other DNA sequences to one another on the same chromosome. The closer two genes or sequences are to each other on a chromosome, the greater the probability that they will be inherited together. They are inherited as a group during cell division, they act and move as a unit rather than independently.
[#380] The first cross between bread wheat and rye was made by Rimpau in
Correct Answer
(A) 1890
Explanation
Solution: The first cross between bread wheat and rye was made by Rimpau in 1890. In 1888, a partially-fertile hybrid was produced by Wilhelm Rimpau, "Tritosecale Rimpaui Wittmack". Such hybrids only germinate when the chromosomes spontaneously double. When crossing wheat and rye, wheat is used as the female parent and rye as the male parent (pollen donor).