Chapter 10, Problem 24A

Summary Introduction

Introduction:

The study of heredity is called genetics. Gregor Mendel was a mathematician whose experiments with garden pea plants gave insight into the inheritance of traits. He developed the law of segregation and law of independent assortment.

Answer to Problem 24A

Correct answer :

The correct answer is option B. gene linkage

Explanation of Solution

Explanation/justification for the correct answer:

OptionB. gene linkage −Mendel developed the law of independent assortment which states that a random distribution of alleles occur during gamete formation. Genes on separate chromosomes sort independently during meiosis.

Gens that are located close to each other on the same chromosome are said to be linked. Many experiments have confirmed that linked genes travel together during meiosis. The linkage of genes on a chromosome is an exception to the law of independent assortment because linked genes do not segregate independently.

Hence, this is the correct option.

Explanation for incorrect answer:

Option A. crossing over- Crossing over is the process by which the genetic material between non sister chromatids of homologous chromosomes is exchanged. It results in new combinations of genes in the daughter cells.It is not an exception to law of independent assortment.

Hence, this is not the correct option.

Option C. polyploidy- Polyploidy cells have one or more extra sets of chromosomes. For example there could be a triploid organism with 3n number of chromosomes. Polyploidy is rare in animals except in earthworms and goldfish. It is lethal in humans but is very common in flowering plants. It follows law of independent assortment. Hence, this is not the correct option.

Option D. law of segregation- Mendel’slaw of segregation states that the two alleles for each trait separate during meiosis. The two alleles unite during fertilization. This law follows the law of independent assortment as the two alleles for a trait are distributed randomly during gamete formation. Hence, this is not the correct option.