Chapter 9, Problem 1CC

Connecting the Concepts

1. Complete this concept map to help you review some key concepts of genetics.

Summary Introduction

To complete: The given map showing some key concepts of genetics.

Introduction: Genetics forms the basis of heredity. It is the study of genes, inheritance patterns, and their expression leading to various traits in living beings.

Answer to Problem 1CC

The Fig.1 provides the vital concepts of genetics in a nut shell.

Pictorial representation: Fig. 1 shows the completed map key concepts of genetics.

Fig.1:Key concepts of genetics

Explanation of Solution

(a)

Correct answer: Alleles

Explanation: Genes have alternate forms known as alleles. The two alleles of a gene segregate into different gametes and are transmitted to offspring. Hence, the correct answer is alleles.

(b)

Correct answer: Loci

Explanation: Genes are DNA sequences that code for specific traits. The specific position of a gene on a chromosome is known as locus. The plural of locus is loci. Hence, the correct answer is loci.

(c)

Correct answer: Homozygous

Explanation: The alleles of a gene segregate into gametes and transmitted to offspring. They are dominant and recessive alleles. When the two alleles are same in an individual(either dominant or recessive), its genotype is homozygous. Hence, the correct answer is homozygous.

(d)

Correct answer: Dominant

Explanation: Dominance in alleles of a gene occurs when a phenotypic effect of one allele suppresses the phenotypic effect of a second allele. If the two alleles are different in an individual, then the dominant allele out of the two alleles expresses itself and determines the phenotype. Hence, the correct answer is dominant.

(e)

Correct answer: Recessive

Explanation: A dominant allele masks the expression of a second allele. The masked allele is known as recessive because its phenotypic effect is suppressed. Hence, the correct answer is recessive.

(f)

Correct answer: Incomplete dominance

Explanation: Dominance explains how different alleles of a gene express themselves. Some genes show incomplete dominance, which means that individuals with homozygous alleles produce offspring that is intermediate of the two parent alleles. Hence, the correct answer is incomplete dominance.