NCERT Solutions for Class 10 Science Chapter 8 Heredity

NCERT Solutions for Class 10 Science Chapter 8 Heredity Download PDF

Get easy access to NCERT Solutions that cover all important concepts from the Heredity chapter. The Heredity Class 10 questions and answers PDF can be accessed offline without using the internet. Students can study in an organised way without getting lost.

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Also Read,

• NCERT Exemplar Solutions for Class 10 Science Heredity and Evolution

• NCERT Chapter Notes for Class 10 Science Heredity

In-Text NCERT Exercise Class 10 Science Chapter 8 Heredity Question Answer

In this section, students will see the detailed answers. These questions are one of the most important parts of understanding the topics. Students must go through the Class 10 Science Chapter 8 Heredity question answer, which is prepared according to the latest NCERT guidelines, to make their base stronger.

Exercise 8.1

Q1. If trait A exists in 10% of a population of an asexually reproducing species and trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Answer:

Trait B is more likely to have arisen earlier because it has a higher percentage of the population, and in asexual reproduction, traits are carried over to the next generation with minimal changes.

For example, all the sugarcane in the field that reproduces asexually have almost similar characteristics; however, the animals and humans that reproduce sexually have more variation of traits in the next generation.

Q2. How does the creation of variations in a species promote survival?

Answer:

Variation in our characteristics occurs due to sexual reproduction and inaccurate copying of DNA. The varied characteristics that are suited for survival are passed on to the next generation more easily, and the characteristics that are not favourable for survival will vanish after some generations.

Favourable variations help a species to adapt to changes in its environment, and they promote the survival of a species.

Exercise 8.2

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

Answer:

Mendel crossed a pure-breeding tall plant with a pure-breeding short plant.

1. In the first generation (F₁), all of the plants were tall. The short trait was not visible.

2. In the second generation (F₂), which was produced by self-pollinating the F₁ plants, the short trait reappeared, and the plants were in a ratio of 3 tall to 1 short.

This showed that the tall trait was dominant because it was expressed in the F₁ generation and hid the short trait. The short trait was recessive because it was masked in the F₁ generation but reappeared in the F₂.

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

Answer:

Mendel performed a dihybrid cross between pure-breeding tall plants with round seeds and short plants with wrinkled seeds. In the next generation, he observed not only the original combinations (tall-round and short-wrinkled) but also new combinations like tall-wrinkled and short-round were formed.

This result showed:
Tall and Round + Short and Wrinkled → Tall and Round + Tall and Wrinkled + Short and Round + Short and Wrinkled

The appearance of new trait combinations like tall-wrinkled and short-round proved that the inheritance of one trait (like plant height) does not depend on the inheritance of another trait (like seed shape).

Hence, he concluded that traits are inherited independently

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:

No, this is not enough information. Blood group A can be AA or AO. If the father is AO and the mother is OO, the child can be O. So, without knowing the parents’ exact genotype or all children’s blood groups, we cannot say which trait is dominant.

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

Answer:

Half the male gametes have X chromosomes, and the other half have Y chromosomes. A human male has one X chromosome and one Y chromosome. In other words, the human male has one X chromosome and one Y chromosome. On the other hand, all-female gametes have only X chromosomes. If a sperm carrying a Y chromosome fertilises an ovum, then the child born will be a boy.

On the other hand, if a sperm carrying X chromosomes fertilises an ovum, then the child born will be a girl.

X + X = Girl

X + Y = Boy.

NCERT Solution Class 10 Science Chapter-End Exercise Heredity Chapter

Given below are the Heredity question answer, which helps in revising the concepts thoroughly and easily.

Q1. A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic makeup of the tall parent can be depicted as

(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw

Answer:

As half the progenies are short, this implies that the parent plant also will have a collection of short genes. Also, since all progenies bore violet flowers, the violet colour is dominant over white.

Hence, TtWW might be the correct answer.

Q2. A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?

Answer:

No, we cannot say anything for sure based on this information alone.

The observation that children with light-colored eyes are likely to have parents with light-colored eyes is true for both dominant and recessive traits. For example:

• Dominant Trait: If the light-eyed trait were dominant, a light-eyed parent would pass that trait to their children, and they would have light eyes.

• Recessive Trait: Light-colored eyes are actually a recessive trait. For a child to have light eyes, they must receive a recessive allele from both parents. Therefore, if both parents have light eyes, all of their children will also have light eyes.

The only way to confirm if a trait is dominant or recessive is to observe a cross where a trait disappears in one generation and reappears in the next (like Mendel's experiments) or to see a child with the recessive trait born to parents who show the dominant trait.

Q3. Outline a project which aims to find the dominant coat colour in dogs.

Answer:

(i) Select two varieties of dogs, one with white coat colour, the other with black coat colour.

(ii) Crossbreed them, taking a male dog from one variety and a female dog from the other variety.

(iii) Observe the colour of the offspring of the F₁ generation.

(iv) Now, bring about breeding among the organisms of the F₁ generation.

(v) Observe the coat colour of the organisms (pups) of the F₂ generation and note the variations in coat colour.

(vi) Draw conclusions based on your study.

One of the probable inheritance patterns may be as follows.

Phenotypic ratio = 3: 1,

Black coat colour (3): White coat colour (1)

Q4. How is the equal genetic contribution of male and female parents ensured in the progeny?

Answer:

The equal genetic contribution of male and female parents is ensured by the inheritance of equal chromosomes from both sides. Humans have 23 pairs of chromosomes. Out of these, the first 22 pairs are called autosomes, and the 23rd pair is known as the sex chromosomes (X and Y). Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). During reproduction, the male germ cell (sperm) and the female germ cell (egg), both haploid, fuse to form a fertilised ovum, which is diploid. This fertilised ovum gets an equal number of chromosomes (23 each) from both the mother and the father.

The father contributes 22 autosomes and either an X or Y chromosome, while the mother contributes 22 autosomes and one X chromosome. This way, the genetic material in the offspring comes equally from both parents.

How to Solve Heredity Class 10 Question Answer?

Start with a careful read of the chapter to learn about the basic principles of heredity, including how characteristics are inherited from parents to children.

• Concentrate on Mendel's laws of inheritance because they are the main principles that describe dominant and recessive characteristics.

• Take note of major topics such as sex determination and acquired and inherited characteristics.

• Focus on the important definitions and terms as sometimes questions are asked from the definitions as well.

• Use diagrams and examples given in the Class 10 Science Chapter 8 Heredity question answer to explain difficult topics.

• Carefully practice exercise questions to prepare well for exams. The NCERT Solutions for Class 10 Science give students an idea of how questions are framed in the exam.

Important Topics of NCERT Science Chapter 8 Heredity Class 10

Heredity is a chapter that explains how traits are passed from parents to offspring through genes. Given below are the topics that are included in this chapter. To gain clarity on these topics, students can use the NCERT Solutions for Class 10 Science Chapter 8 Heredity.

• Accumulation Of Variation During Reproduction

• Inherited Traits

• Rules for the Inheritance of Traits – Mendel’s Contributions

• How do these traits get expressed?

• Sex Determination

Also, check the NCERT Books and the NCERT Syllabus here:

• NCERT Books Class 10 Science

• NCERT Syllabus Class 10 Science

• NCERT Books Class 10

• NCERT Syllabus Class 10

Important Questions from NCERT Science Chapter 8 Heredity Class 10

This chapter helps students understand the basic principles of inheritance and how genetic variation occurs in living organisms. Given below is a question along with the detailed answer. Other types of questions are present in the NCERT Solutions for Class 10 Science Chapter 8 Heredity.

Question 1: In an experiment to study the independent inheritance of two separate traits — shape and colour of seeds — the ratio of the different combinations in F₂ progeny would be:

A. 1 : 3

B. 1: 2:1

C. 9:3:3:1

D. 9:1:1:3

Answer: The correct answer is option(C), 9:3:3:1

Explanation:

According to the question, when two traits are taken, then that is a classic Mendelian dihybrid cross. The F₂ generation shows a phenotypic ratio of 9:3:3:1, in which:

- 9 shows both dominant traits

- 3 show one dominant and one recessive trait

- 3 shows the other dominant and one recessive trait

- 1 shows both recessive traits

Question 2: The total normal number of chromosomes restored in the progeny if

A. Two genes combine

B. Two germ cells combine

C. Two nuclei combine

D. Two eggs combine

Answer: The correct answer is option(B), Two germ cells combine

Explanation:

When two germ cells of each parent combine, they will restore the total (normal number) of chromosomes in the progeny, ensuring the stability of the DNA of the species.

Question 3: A child who inherits the X chromosome from their father will be a

A. boy

B. girl

C. could be either (boy or girl )

D. Both (c) and (d).

Answer: The correct answer is option(B), girl

Explanation:

All the children will inherit an X chromosome from their mother, regardless of whether they are boys or girls and thus, the sex of the children will be determined by what they inherit from their father. Therefore, if a child inherits the X chromosome from their father, they will be a girl (XX).

Question 4: Males have a pair of chromosomes in which

A. Both are normal-sized X.

B. one in a normal-sized Y and the other is a short one called X.

C. The Y chromosome is absent

D. one in normal-sized X and the other is a short one called Y.

Answer: The correct answer is option(D), one in normal-sized X and the other is a short one called Y

Explanation:

Males have a mismatched pair of chromosomes in which one is a normal-sized X and the other is a short one called Y.

Question 5: Genes are present as a short thread of DNA that helps to determine the inheritance of traits.

A. True

B. False

Answer: The correct answer is option(B), False

Explanation:

Genes are not present as a single long thread of DNA. Instead, each set of genes is present as independent pieces, called chromosomes, that help to determine the inheritance of traits from the parents to their offspring.

Question 6: Green colored formed out of red-colored beetles due to

(A) sexual reproduction

(B) genetic variation

(C) genetic drift

(D) migration

Answer: The correct answer is option(B), genetic variation

Explanation:

Red-colored beetles were continuously growing by sexual reproduction. Sexual reproduction caused some genetic variations, and due to the variation, one green beetle was formed. Hence, the correct option is (B).

Question 7: Analogous organs have

(A) Same structure, same function

(B) Different structure, different function

(C) Same structure, different function

(D) different structure, same function

Answer: The correct answer is option(D), different structure, same function

Explanation:

Analogous organs are those types of organs that are different in structure but perform similar functions. Examples of analogous organs are the wings of bats, birds, and insects. Hence, the correct option is (D)

Question 8: Humans carry ____ number of chromosomes.

(A) 23

(B) 46

(C) 27

(D) 22

Answer: The correct answer is option (B), 46

Explanation:

Humans carry 23 pairs of chromosomes, totalling 46 chromosomes. Hence, the correct option is (B).

Question 9: How many contrasting pairs of pea plants were studied by Mendel in his experiments?

(a) 8

(b) 7

(c) 6

(d) 5

Answer: The correct answer is option (b), 7.

Explanation:

Seven pairs of contrasting visible characters of the garden pea plant were studied by Mendel in his experiments. Hence, the correct option is (b).

CBSE Board PYQs Heredity Class 10 Science

These Heredity Class 10 CBSE Board PYQs focus on sex determination, Mendel’s dihybrid cross ratio, gene-protein interaction, and inheritance of traits. They strengthen concepts from the NCERT Solutions Class 10 Science Chapter 8 Heredity

Question: "Sex of the children is determined by the type of sex chromosome which they inherit from their father." Justify the statement.

Answer: The statement is true because the sex of a child is determined by the combination of sex chromosomes inherited from both parents. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The mother always passes an X chromosome to the child, but the father can pass either an X or a Y chromosome. If the father passes an X chromosome, the child will be female (XX), and if he passes a Y chromosome, the child will be male (XY).

Question: A pure pea plant having round (R), yellow (Y) seeds is crossed with another pure pea plant having wrinkled (r), green (y) seeds. Subsequently, F1 progeny is self-pollinated to obtain F2 progeny.

State the reason for obtaining seeds of the new combination of traits in F2 generation.

Answer: In the second generation, that is, in the F2 generation, there are new combinations of characters due to the independent assortment of genes. According to Mendel's law of independent assortment, the gene that controls the shape of the seed and the gene that controls seed colour assort independently when gametes are being formed. Therefore, when F1 plants (RrYy) are self-pollinated, a combination of round green and wrinkled yellow seeds and round yellow and wrinkled green seeds is formed.

This gives a phenotypic ratio of 9:3:3:1 in the F2 generation with four different combinations of characters. Mendel's dihybrid cross with pea plants effectively explained how characters are inherited independently of one another when they are present on different chromosomes.

Question: Name the section of DNA that controls the 'characteristics' in an organism.

Answer: The section of DNA that controls the characteristics in an organism is called a gene.

• A gene is a specific sequence of DNA that contains the instructions for producing proteins. It helps in determining the traits or characteristics of the organism.

• They also influence characteristics like eye colour, height, and risk of certain diseases. It is located on chromosomes within the nucleus of the cell.

Question: Explain how the proteins control the 'characteristics' in an organism with the help of an example of a 'tallness' trait in a pea plant.

Answer: Proteins regulate an organism's characteristics by controlling gene expression and protein synthesis. For instance, the tallness gene in pea plants is expressed to synthesise a particular protein. The protein regulates the synthesis of growth hormones, like gibberellins, which stimulate stem elongation and plant height. When the gene is not functioning, the required protein is not synthesised, hormone synthesis is impaired, and the plant does not grow tall. This indicates how genes indirectly affect characteristics through the proteins they encode.

What Students Learn from Heredity NCERT Solutions?

This chapter explains how traits are passed from one generation to the next. Students get to know the scientific reasons behind similarities and differences in living beings.

• The Heredity Class 10 question answer explains Mendel’s experiments and their results in a simple way.

• Students learn about dominant and recessive traits with examples.

• They also explore the concept of sex determination, which takes place in humans.

• The Class 10 Science Heredity question answer helps in understanding variations within species.

• Students also understand how parental traits are transferred through genes.

Why are Class 10 Science Chapter 8 Heredity NCERT Solutions Important?

The heredity chapter helps students understand how characteristics are passed from one generation to another. Important topics such as genes, chromosomes, dominant and recessive traits, and Mendel's experiments are also included.

1. Using the Class 10 Science Chapter 8 Heredity NCERT Solutions, students learn the basic concepts of inheritance and genetics.

2. The solutions also explain Mendel’s experiments and laws of inheritance in a simple and easy-to-understand manner.

3. Topics of the Heredity chapter form the base for concepts like Principles of Inheritance and Variation, and Molecular Basis of Inheritance in classes 11 and 12.

4. Genetics-based questions are frequently asked in the NEET and other competitive exams, making the solutions very important.

NCERT Solutions Chapter-wise for Class 10 Science

Below are the Chapter-wise solutions that provide clear explanations and step-by-step answers for better understanding.