Chapter 12, Problem 1SQ

Summary Introduction

Introduction:

Asexual reproduction generates genetically identical offspring from a single parent. In sexual reproduction, the offspring inherits genes from two parents. Also, the offspring produced are genetically unique.

Answer to Problem 1SQ

Correct answer:

The main evolutionary advantage of sexual over asexual reproduction is that it produces more variation among offspring. Hence, the correct answer is option b.

Explanation of Solution

Reason for correct answer:

Option b. is given as “more variation among offspring”.

All offspring of an asexual reproducer are clones. They have the same alleles as their parent. Environment is constantly changing and may not be always favorable. Individuals that are identical are vulnerable to the environmental changes. The genetic diversity gives the sexual reproducers an evolutionary advantage. The genetic information of two parents with different alleles is combined in sexual reproduction. The offspring differ from each other and their parents due to inheritance of different combinations of parental alleles. Some offspring may adapt perfectly to a new environmental challenge. As a result, they have better chances of survival in the changing environment. Therefore, the evolutionary advantage of sexual reproduction is that it produces more variation among offspring than asexual reproduction.

Reason for incorrect answer:

Option a. is given as, “more offspring per individual”.

Asexual reproduction generally produces more offspring than sexual reproduction. The offspring have the same allele as their parent. Evolution is defined as a change in the characteristics of a species over several generations and it relies on natural selection. This indicates that more offspring per individual is not an evolutionary advantage. Hence, option a. is incorrect.

Option c. is given as, “healthier offspring”.

Some offspring may have inherited traits that help them survive and reproduce in a new environment. This may occur in both asexual and sexual reproducing organisms. However, sexual reproduction produces more variation among offspring than asexual reproduction is an evolutionary advantage.

Hence, option c. is incorrect.

Hence, the options a. and c. are incorrect.

Conclusion

Variation among offspring in sexual reproduction provides an evolutionary advantage. Thus, the correct option is b.