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_________is the original source of new alleles.
| a. Mutation | c. Gene flow |
| b. Natural selection | d. Genetic drift |
Introduction:
Genes control the phenotypic expression of an organism. For a single character, different organisms can show different variations for a single character. These variations arise due to different alleles for a single gene. Alleles are different forms of a single gene. During sexual reproduction, offsprings get alleles for a gene both the parents
Answer to Problem 1SA
Correct answer:
Mutation is the original source of new alleles. Hence, the correct answer is option a.
Explanation of Solution
Reason for correct answer:
Option a. is given as “Mutation”.
Mutations cause a change in the amino acid sequence of a gene. These changes result in new phenotypic expressions of that gene in the organism. Mutations cause the formation of alleles that cause various phenotypic expressions of the same character in the mutated organism. Therefore, it can be said that the source of new alleles are mutations in the genes of organisms.
Reason for incorrect answer:
Option b. is given as, “Natural selection”.
Natural selection occurs due to the accumulation of variations over generations. These traits are inherited and are different due to crossing over during reproduction. New alleles are not formed by this process. Hence, option b. is incorrect.
Option c. is given as, “Gene flow”.
Gene flow refers to the process by which new genes enter a population or some genes exit a population. There is no creation of new alleles. Hence, option c. is incorrect.
Option d. is given as, “Genetic drift”.
Genetic drift allows the change of allele frequency in a population. Inherited traits accumulate over generations leading to the gradual drift of population. The changes are random events and there is no formation of new alleles. Hence, option d. is incorrect.
Hence, the options b., c., and d. are incorrect.
The original source of new alleles is a mutation. Thus, the correct option is a.
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BIOLOGY:CONCEPTS+APPL.(LOOSELEAF)
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