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Read the following and answer any given below:MUTATION BREEDING :“Mutation is a sudden heritable change in a characteristic of an organism.” The mutation which occur in nature at a very low rate are called Spontaneous mutations. Its Frequency is 10-6 (I.e., 1 in10 lacs). The mutations which are created artificially by a treatment with certain physical or chemical agents are called induced mutations. The agents use to produce such mutations are Known as mutagens. The utilization of induced mutations of crop improvement is known as Mutation breeding. Induced mutations usually produce such alleles which are produced by spontaneous mutations. Their main advantage is the very high frequency at which they are obtained. In Mutation breeding, usually the seeds are treated with suitable mutagen then these seeds are grown in the field and self-Pollinated. Progeny from the seeds of these plants are grown during the next crop season. These plants’ are carefully observed to identify and select mutations of interest. Ultimately a desirable mutant line may be obtained which may be better enough to released as a new variety.(i) Mutation is a. Sudden change in morphologyb. Change in characters c. Change in heritable characters d. None of these (ii). Gene mutation is caused by a. Reproduction b. Linkage c. Change in the sequence of nitrogenous base d. Change in the sequence of genes in DNA (iii). The concept of sudden genetic change which breeds true in an organism is visualised in the principle of a. Natural selection b. Heredity c. Variations d. Mutations (iv). Mutations occur a. Mainly in haploid cells b. Mainly in diploid cells c. Whenever cells are exposed to X-rays d. In any cell of the body exposed to radiation (v). Assertion: Haploids are used to study mutation. Reason: Most of the mutations are recessive. a. Both assertion and reason are true, and reason is the correct explanation of assertion. b. Both assertion and reason are true, but reason is not the correct explanation of assertion. c. Assertion is true but reason is false d. Both assertion and reason are false.

Answer»

(i) c. Change in heritable characters

(ii) d. Change in the sequence of genes in DNA

(iii) d. Mutations

(iv) c. Whenever cells are exposed to X-rays

(v) b. Both assertion and reason are true, but reason is not the correct explanation of assertion.



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