Chapter 10, Problem 22A

Summary Introduction

To replace:

The underlined words with correct vocabulary terminthe given sentence.

Introduction:

Meiosis is reduction division during which the number of chromosomes is halved. It is used to produce gametes which fertilize to produce diploid zygote. 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.

Answer to Problem 22A

Both meiosis and crossing over contribute to the amount of genetic recombination in a particular species.

Explanation of Solution

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.

Genetic variation is also possible during crossing over and fertilization when gametes randomly combine.

Meiosis and crossing over produces new combination of genes. This new combination of genes is called genetic recombination.

Independent assortment of genesalso contributes to genetic recombination. Genes that are linked together on the same chromosomes usually travel together in a gamete.The crossing over of linked genes is a source of genetic variation.

Hence, the correct word in the given sentence is genetic recombination.