Chapter 23, Problem 1TY

 Population geneticists are interested in the genetic variation in populations. The most common type of genetic change that causes polymorphism in a population is

1. a. a deletion of a gene sequence.
2. b. a duplication of a region of a gene.
3. c. a rearrangement of a gene sequence.
4. d. a single-nucleotide substitution.
5. e. an inversion of a segment of a chromosome.

Summary Introduction

Introduction: Polymorphism can be defined as a process by which a particular trait displays several types of variations among a population. A polymorphic population shows more than one phenotype for that particular trait.

Answer to Problem 1TY

Correct answer: A single-nucleotide substitution is the most common type of genetic change that leads to polymorphism in a population. Hence, the correct answer is option d.

Explanation of Solution

Reason for correct answer:

Single-nucleotide substitution results in the change in genetic makeup due to a change in a single nucleotide. These changes are responsible for coding different types of amino acids, which in turn will code for different proteins. Different functional protein will lead to the generation of various types of phenotypes among the members of a population. So, they are the simplest and common type of genetic change that occur in a gene.

Option d. is given as “a single-nucleotide substitution”.

The most common type of genetic change that is responsible for causing polymorphism is single-nucleotide substitution. Hence, the correct answer is option d.

Reasons for incorrect answer:

Option a. is given as, “a deletion of a gene sequence”.

A deletion in gene sequence can cause variations in the genome. However, it is not the most common type of genetic change that results in polymorphism. Hence, option a. is incorrect.

Option b. is given as, “a duplication of a region of a gene”.

Duplication of a region of gene occurs in extreme cases of genome repairing process. It also occurs due to the various types of mutation at the time of replication of genetic material. So, it is not the most common type of genetic change. Hence, option b. is incorrect.

Option c. is given as, “a rearrangement of a gene sequence”.

A rearrangement of a sequence of gene can cause polymorphism to some extent but it occurs majorly in case of genome repair. So, it is not the most common type of genetic change. Hence, option c. is incorrect.

Option e. is given as, “an inversion of a segment of a chromosome”.

Process of inversion of a segment of gene sequence is not at all related with the process of polymorphism. Hence, option e. is incorrect.

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

Conclusion

Single-nucleotide substitution is responsible for polymorphism. It is the most common process which results in genetic changes among the gene sequences and leads to the process of polymorphism very frequently.