NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution of Page 133

Q1: How do Mendel’s experiments show that traits may be dominant or recessive?

Answer:

To show that traits may be dominant or recessive. Mendel chose true breeding tall (TT) and dwarf (tt) pea plants for the experiment. He crossed the two breeds and observed the first filial generation(F1). He found that the seeds formed after fertilization were grown and all of them were tall (Tt).

Then, Mendel self-pollinated these plants and observed F2 generation in his observation, he found that one-fourth of F2 generation was short.

From this experiment, he concluded that the F1 generation appeared tall because the tall trait is dominant over the dwarf trait as Fi plants are not true-breeding and carry both short and tall traits.

Q2: How do Mendel’s experiments show that traits are inherited independently?

Answer:

To show that traits are inherited independently  Mendel crossed pea plants having round green seeds (RRyy) with pea plants having wrinkled yellow seeds (rrYY).

As the F1 plants are formed after crossing pea plants having green round seeds and pea plants having yellow wrinkled seeds, the F1 generation formed bore both characters in them. Although, the plants had round and yellow seed colors because they are dominant characters.

Then, F1 progeny was self-pollinated and the F2 generation have yellow round seeds, green round seeds, yellow wrinkled seeds, and green wrinkled seeds in the ratio of 9:3:3:1.

Q3:  A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O  is dominant? Why or why not?

Answer:

The information given as the father having blood group A and the mother blood group O is not adequate to conclude that either the traits – blood A or O is dominant. In order to know which trait is dominant we will have to know about all the progeny of the blood group as blood group A can have genotype AA or AO.

Q4: How is the sex of the child determined in human beings?

Answer:

As we know in human beings, during reproduction the gametes receive half-half chromosomes from each of their parents in equal genetic proportion. Female gametes are composed of 22 autosomes and an X chromosome and male gametes are composed of 22 autosomes and either a X or Y sex chromosome. Hence, in this process of transferring genetic materials, the mother gives only the X chromosome whereas, the father provides the X or Y chromosome which determines the sex of the child. If the X chromosome of female fuses with the X chromosome of a male it will be a girl, or if it fuses with the Y chromosome of a male it will be a boy.

NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution: This article includes free NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution. It has been developed by the subject matter experts at GFG, according to the latest CBSE Syllabus 2023-24, and guidelines to help the students of Class 10 create a solid conceptual base for Chapter 9 Heredity and Evolution Class 10 Science and ace their exams.

NCERT CBSE Chapter 9 Heredity and Evolution of Class 10 explains the role of Heredity in the variation and evolution of organisms, over a period of time. To revise the basic concepts of Chapter 9 Heredity and Evolution NCERT Class 10 Science, head over to: CBSE NCERT Class 10 Science Chapter 8 Heredity and Evolution Notes for quick revision and class notes.

The solutions to all the exercises in NCERT Class 10 Science Chapter 9 Heredity and Evolution have been collectively covered in NCERT Solutions for Class 10.