This fascinating chapter of NCERT Solutions for Class 10 Science Chapter 8, Heredity and Evolution, helps us understand how traits pass from parents to offspring and how species have transformed over millions of years to create the incredible diversity of life we see today. Whether it's why you resemble your parents, how fossils tell us stories of ancient life, or why giraffes have long necks, this chapter connects the dots between inheritance patterns and the gradual changes that shape all living organisms. This chapter is part of the comprehensive NCERT Solutions Class 1o Science series, which covers all chapters in detail.
The chapter equips students with essential skills to understand Mendel's laws of inheritance, interpret genetic crosses, comprehend Darwin's theory of natural selection, analyze evidence of evolution through fossils and comparative anatomy, and explore how variations drive speciation. Every solution has been designed keeping CBSE board exam patterns in mind, ensuring students develop both conceptual clarity and problem-solving confidence. By mastering this chapter, students build a strong foundation for genetics, evolutionary biology, molecular biology, and biodiversity studies in higher classes.
NCERT Solutions for Class 10 Science Chapter 8 - All Exercise Questions
Q.
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 make-up of the tall parent can be depicted as
(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw
Q.
An example of homologous organs is
(a) our arm and a dog’s fore-leg.
(b) our teeth and an elephant’s tusks.
(c) potato and runners of grass.
(d) all of the above.
Q.
In evolutionary terms, we have more in common with
(a) a Chinese school-boy.
(b) a chimpanzee.
(c) a spider.
(d) a bacterium.
Q.
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?
Q.
How are the areas of study – evolution and classification – interlinked?
Q.
Explain the terms analogous and homologous organs with examples.
Q.
Outline a project which aims to find the dominant coat colour in dogs.
Q.
Explain the importance of fossils in deciding evolutionary relationships.
Q.
What evidence do we have for the origin of life from inanimate matter?
Q.
Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?
Q.
How is the equal genetic contribution of male and female parents ensured in the progeny?
Q.
Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?
Class 10 Chapter 8 Science Questions & Answers –Heredity and Evolution
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 make-up of the tall parent can be depicted as
(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw
Solution:
(c) TtWW
Explanation: Since all the progeny bore violet flowers, it means that the tall plant having violet flowers has WW genotype for violet flower colour. Since the progeny is both tall and short, the parent plant was not a pure tall plant; its genotype must be Tt. Therefore, the genetic makeup of the tall parent can be depicted as TtWW.
Gametes of TtWW (Tall, violet flower) will be TW, TW, tW and tW.
Gametes of ttww (Short, white flower) will be tw, tw, tw and tw.
On crossing-
Therefore, half the progeny will be tall and half will be short but all of them have violet flowers.
Q2.An example of homologous organs is
(a) our arm and a dog’s fore-leg.
(b) our teeth and an elephant’s tusks.
(c) potato and runners of grass.
(d) all of the above.
Solution:
(d) all of the above
Explanation: Homologous organs are the organs having the same structure, origin and constituting parts but different functions.
Q3. In evolutionary terms, we have more in common with
(a) a Chinese school-boy.
(b) a chimpanzee.
(c) a spider.
(d) a bacterium.
Solution:
(a) A Chinese school-boy
Explanation: All the human beings present on the earth belong to a species Homo sapiens.
Q4. 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?
Solution:
Let us assume that children with light coloured eyes can either have LL or Ll or ll genotype. If the children have LL genotype, then their parents will also be of LL genotype
LL X LL
LL
If the children with light-colouered eyes have ll genotype, then their parents will also have ll genotype.
ll X ll
ll
Therefore, from the above given information, it cannot be concluded whether light eye colour is dominant or recessive.
Q5. How are the areas of study – evolution and classification – interlinked?
Solution:
Genetic variations form the basis for evolution and play an important role in the origin of new species. Because of similarity in their inherited body designs organisms appear to be the same. The two species are said to be closely related if they have characteristics in common. And they are likely to have a common ancestor more recently. Based on the similarities and differences of characteristic, classification of organisms necessarily involves, organising them in different groups. Among diverse species, classification of organism helps us in recognising the fundamental arrangement of a hierarchical structure. Classification helps us in establishing the resemblances and relationships between various organisms and also facilitates studies or research of wide variety related with organisms. In fact, classification of species is an expression of their evolutionary relationship. Thus, we can say the areas of study – evolution and classification are interlinked.
Q6. Explain the terms analogous and homologous organs with examples.
Solution:
Analogous organs: The organs having the same functions but different in structure, origin and constituting parts are called analogous organs. For example, the wings of bats and the wings of birds are analogous organs as their origins, designs, structure and components are different but they have a common use for flying.
Homologous organs: The organs having the same structure, origin and constituting parts but different functions are called homologous organs. For example: the forearms of a horse and the hands of human.
Q7. Outline a project which aims to find the dominant coat colour in dogs.
Solution:
Let us assume that a male dog having genotype BB (black skin coat) is mating with a female dog having genotype bb (white skin coat).
Offspring produced by this mating are all black and have a genetic make-up Bb.
Hence, it can be concluded now that black skin coat is dominant over the white skin coat.
Q8. Explain the importance of fossils in deciding evolutionary relationships.
Solution:
Fossils are the remains or preserved traces of organisms, which died millions of years ago. The study of fossils has helped us in establishing evolutionary link between the two species. The study of fossils also helps in identifying the origin of new species from the existing one. So, fossils have an importance in deciding evolutionary relationship.
Q9. What evidence do we have for the origin of life from inanimate matter?
Solution:
An experiment conducted in 1953, by Stanley L Miller and Harold C Urey serves the evidence for the origin of life from inanimate matter. In the experiment, they created an atmosphere containing molecules like ammonia, methane and hydrogen sulphide, but no oxygen. This was similar to the atmosphere that was thought to exist on the early earth. The gases were maintained at a temperature just below 100°C and to stimulate lightening sparks were passed through the mixture of gases. At the end of the week, almost 15 % of the carbon from methane gas had been transformed into simple compounds of carbon including amino acids which make up protein molecules and support life in its basic form. Thus, suggesting that life arose anew on earth.
Q10. Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?
Solution:
Sexual reproduction gives rise to more viable variations than asexual reproduction. It is because of the inbuilt tendency to variation during reproduction, both because of errors in DNA copying, and modes of sexual reproduction. The genes of the traits or characteristics are transmitted from one generation to the next generation and dominant characters are expressed while asexual reproduction not only helps in survival of species but also support diversity in long run. Drift in genetic traits get accumulated spanning across generations, this gives rise to formation of new species.
Q11. How is the equal genetic contribution of male and female parents ensured in the progeny?
Solution:
Equal genetic contribution of male and female parents is ensured in the progeny through inheritance of equal number of chromosomes from both parents. For example, in humans, there are 23 pairs of chromosomes. Out of these 23 pairs, the 22 pairs are known as autosomes and the remaining one pair is known as sex chromosomes represented as X and Y. Females have a pair of two X sex chromosomes whereas males have a pair of one X and one Y chromosome.
The male parent produces gametes having 22 autosomes and one X or Y chromosome where as the female parent produces gamete having 22 autosomes and one X chromosome. During fertilisation, the male gamete fuses with the female gamete resulting in the formation of zygote. The zygote in the progeny receives an equal contribution of genetic material from both the parents.
Q12. Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?
Solution: We agree with the statement that only variations that confer an advantage to an individual organism will survive in a population. All the variations do not survive in the environment. The chances of their survival depend on the acceptance or rejection by the nature. Different individual have different kinds of variations. A polar bear can withstand extreme cold, will survive better in cold regions. Selection of variants by nature establishes the basis for evolution.
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NCERT Solutions for Class 10 Science Chapter 8 – FAQs
Q1. What is the difference between inherited and acquired traits?
Inherited traits are characteristics passed from parents to offspring through genes, such as eye color, blood group, hair texture, and height. These traits are present in the DNA of reproductive cells (gametes) and are transferred to the next generation. Acquired traits are characteristics developed during an individual's lifetime due to environmental factors, lifestyle, or use and disuse of organs, such as muscular body from exercise, language skills, or scars from injuries. Acquired traits are not encoded in the DNA of germ cells and therefore cannot be passed to offspring. For example, if a parent builds strong muscles through weight training, their children will not automatically inherit those muscles—they would need to exercise themselves to develop similar traits.
Q2. How does Mendel's experiment with pea plants explain the laws of inheritance?
Gregor Mendel conducted experiments on garden pea plants and discovered fundamental laws of inheritance. In his monohybrid cross experiment, he crossed tall pea plants (TT) with short pea plants (tt). The first generation (F₁) produced all tall plants (Tt), showing that the tall trait is dominant. When he self-pollinated F₁ plants, the second generation (F₂) showed a 3:1 ratio of tall to short plants, demonstrating Mendel's Law of Segregation—that paired factors (alleles) separate during gamete formation. His dihybrid cross experiments, crossing plants differing in two traits (like seed shape and color), established Mendel's Law of Independent Assortment—that different traits are inherited independently. These experiments laid the foundation for understanding how traits pass from one generation to the next through discrete units we now call genes.
Q3. What is evolution and what are the main evidences supporting it?
Evolution is the gradual change in inherited characteristics of species over successive generations through natural selection, genetic drift, and mutation. Several types of evidence support evolution: Fossil records show progressive changes in organisms over geological time periods, with simpler life forms in older rocks and complex ones in recent layers. Homologous organs (like forelimbs of humans, whales, bats, and dogs) have similar basic structure but different functions, indicating common ancestry. Analogous organs (like wings of birds and insects) have different structures but similar functions, showing adaptation to similar environments. Vestigial organs (like the human appendix or tail bone) are reduced structures that were functional in ancestors. Additionally, embryological evidence shows similarities in early developmental stages across different species, and molecular evidence from DNA and protein comparisons reveals evolutionary relationships. These multiple lines of evidence collectively demonstrate that life on Earth has evolved from common ancestors over millions of years.