Chapter 10, Problem 23A

Summary Introduction

Introduction:

The main advantage of sexual reproduction is that it produces genetic variation in species. Genetic variation helps species survive better in adverse conditions. Both meiosis and crossing over contribute to the amount of genetic recombination in a particular species.

Answer to Problem 23A

Correct answer :

The correct answer is option A. chromosome number

Explanation of Solution

Explanation/justification for the correct answer:

OptionA. chromosome number −Different organisms have different number of chromosomes but each species has a fixed number of chromosomes. This does not create genetic variation within a species. Hence, this is the correct option.

Explanation for incorrect answer:

Option A. crossing over- Crossingoveris a process in meiosis during which chromosomal segments are exchanged between a pair of homologous chromosomes. This results in exchange of genes between homologous chromosomes. Hence, this is not the correct option.

Option C. meiosis- During meiosis the chromosomes line up at the equator randomly. This results in gametes with different combinations of chromosomes. Depending on how the chromosomes line up at the equator, four gametes with four differentcombinations of chromosomes are formed.Hence, this is not the correct option.

Option D. random mating- Random mating allows organisms to combine their gametes chromosomes differently. This creates genetic variation.Hence, this is not the correct option.