Chapter 21, Problem 1A

Summary Introduction

Introduction:

Inheritance is a process of passing genetic information from parents to the offspring. In humans all cells contain two sets of 23chromosome except for the sex cells. The sex cells have one set of chromosome and when the egg and sperm combine they again form two sets of chromosome in zygote and all the information for the development is stored in the DNA which is transcribed and translated to form proteins.

Answer to Problem 1A

Correct answer:

Genotype of the individual is determined by the DNA which is not expressed until without undergoing transcription and translation. The proteins express in the form of appearance which is known as phenotype of the individual Therefore, option (c) is correct.

Explanation of Solution

Reason for the correct statement:

The DNA determines the genotype of the individual and the information present in the genotype is associated with genetic constitution. The external appearance is the phenotype of the individual which is under the control of the proteins.

Option (c) is given as “genotype; phenotype”.

“The genotype of an organism is determined by the information in the DNA, and the phenotype is determined largely by proteins”, it is the right answer.

Hence, option (c) is correct.

Reasons for the incorrect statements:

Option (a) is given as “phenotype; genotype”.
The genotype is determined by the DNA not the phenotype and the proteins determine the phenotype of the individual not the genotype. So, it is a wrong answer.

Option (b) is given as “locus; phenotype”.
Locus is the position of the gene present on the DNA and the phenotype is determined by the proteins. So, it is a wrong answer.

Option (d) is given as “genotype; sex-linkage”.
The genotype is determined by the information present in the DNA but the sex-linkage is the expression of phenotype of allele present on the sex chromosome which helps in determination of gender of an individual. So, it is a wrong answer.

Option (e) is given as “None of these are correct”.
Since genotype is determined by DNA and phenotype is determined by the expression of proteins is correct. So, it is a wrong answer.

Hence, options (a), (b), (d) and (e) are incorrect.

Conclusion

Genotype of the individual is determined by the DNA which is not expressed until without undergoing transcription and translation. The proteins express in the form of appearance which is known as phenotype of the individual.