Xam Idea Class 10 Science Chapter 9 Solutions: Heredity And Evolution

Xam Idea Class 10 Science Solutions for Chapter 9 – Heredity and Evolution will help you to understand all the basic concepts of the chapter in very little time. In this chapter, you will study the different types of evolutions occurring in animals and insects, how they are similar to each other, how the traits are transferred through one generation to the other, and so on. We have provided stepwise Xam Idea Solutions to each of the questions of the exercises in a systematic way. You will be able to grasp the concepts of the chapter easily with the help of our solutions for Heredity and Evolution.

Xam Idea Class 10 Science Chapter 9 Heredity and Evolution will provide you with 6 exercise sections that are designed according to the latest exam pattern of CBSE. These 6 sections contain a total of 21 questions. The exercises are divided into a variety of questions like Very Short Questions, Short Questions, Long Questions, HOTS, and Value-Based Questions. There are questions based on the classification of species, genetic drift and tracing evolutionary traits. You will also get to understand why offsprings have certain different characteristics than the parents and why is that variation beneficial but not necessary.

Instasolv provides you with the best and easily understandable Xam Idea Class 10 Science solutions to the questions Chapter 9 Heredity and Evolution. All the solutions are designed in a simple way so that you can learn them very easily without taking much time. All solutions are provided with appropriate diagrams and illustrations that will help you to understand the basic concept of the chapter. Our Xam Idea Class 10 solutions provide you with a platform where you can make your learning easy and fast. Here you can cover your syllabus in very less time and can save so much time for the revision.

Introduction Topics for Xam Idea Class 10 Science Solutions Chapter 9 Heredity and Evolution

Sex Determination: The phenomenon of decision or determination of sex of an offspring is known as sex determination. The factors responsible for sex determination are Environmental and Genetic.

  • Environmental:  In certain creatures, the temperature at which the prepared eggs are kept chooses the sexual orientation, for example, turtle. 
  • Genetic: In some animals like humans gender or individual is determined by a pair of the chromosome called sex chromosome

Sex Chromosomes: In people, there are 23 sets of chromosomes. Out of these 22 chromosomes, sets are considered autosomes and the last pair of chromosomes that help in choosing the sex of that individual are called sex chromosome

Traits: There are two types of traits one is Acquired Trait and another one is an Inherited Trait.

Acquired Trait

  • These are the attributes which are created in a person because of exceptional conditions  
  • They cannot be transferred to the progeny
  •  They cannot direct evolution, for example, Low weight of starving beetles. 

Inherited Trait

  •  These are the traits that are passed from one generation to the next.
  • They get transferred to the progeny.
  •  They are helpful in evolution, for example, the color of eyes.

Genetics: Branch of science that deals with Heredity and variation.

  • Heredity:  It implies the transmission of highlights/characters/characteristics starting with one age then onto the next age.
  • Variation:  The distinctions among the animal varieties/populace are called varieties.

Mendel and his work on Inheritance 

  • Gregor Johann Mendel (1822&1884): Started his tests on plant rearing and hybridization. The Mendel is known as the dad of Genetics.
  • Mendel’s Experiments: Mendel directed a progression of trials in which he crossed the pollinated plants to consider one character (at once)
  • Monohybrid Cross: Cross between two pea plants with one set (monohybrid cross) differentiating characters, for example, Tall / Short Plant
  • Dihybrid Cross: A cross macle between two plants having two pairs of contrasting characters is called a dihybrid cross.
  •  eyes and hair


  • Microevolution: It is the evolution that is on a small scale. eg. change in the body colour of beetles.
  • Speciation:  It is the procedure of development of new species. 
  • Species: A group of similar individuals that along to a population that can interbreed and produces fertile offspring.
  • Geneflow: It is an exchange of genetic material by interbreeding between populations of the same species or individuals

Genetic Drift

  •  It is the arbitrary change in the recurrence of alleles (quality pair) in a populace over progressive age
  • Natural Selection: The procedure by which nature chooses and unite those living beings which are all the more reasonably adjusted and has good varieties 
  • Genetic drift takes place due to:
  1. a) Severe changes in the DNA
  2. b) Change in number of chromosomes

Evolution and Classification 

  • Both evolution and classification are interlinked.
  •  The arrangement of species is an impression of their transformative relationship. 
  • The more trademark two species share for all intents and purpose the more intently they are connected.  
  • The more intently they are connected, the more as of late they have a typical progenitor. 
  • Likenesses among living beings permit us to assemble them and to contemplate their trademark.

Tracing Evolutionary Relationships

  • Homologous Organs: These are the organs that have the same basic structural plan and origin but different functions.
  • Analogous Organs: These are the organs that have different origins and structural plans but the same functions.
  • Fossils: The remains and relics of dead organisms of the past.
  • Example :
  1. Fossil of a woolly mammoth
  2. Archeopteryx (fossil bird)
  3. Dead insect caught in hot mud.

Fossils: These are preserved traces of living organisms. Here are some examples. 

  • AMMONITE – Fossil invertebrate
  • TRILOBITE – Fossil in vertebrate
  • KNIGHTIA – Fossil fish
  • RAJASAURUS – Fossil dinosaur skull

Age of Fossils

  • Deeper the fossil, the older it is.
  • Distinguishing the proportions of various of a similar component in the fossil material ie Radio-cell based dating.

Evolution by Stages

Evolution takes place in stages that are bitten by bit over a generation.

Fitness advantage

The Evolution of Eyes

 The advancement of complex organs isn’t unexpected; it happens because of minor changes in DNA, be that as it may, it happens a little bit at a time overages. For example,

  • Flatworm has rudimentary eyes
  • Insects have compound eyes
  • Humans have binocular eyes

Functional Advantage

Evolutions of Feathers

Feathers provide insulation in cold weather but later they became useful for flight. Dinosaurs had quills, yet couldn’t fly utilizing plumes. Flying creatures appear to have later adjusted the plumes to fly.

Artificial Selection: Humans have been an amazing specialist in altering wild species to suit their own prerequisites all through ages by utilizing counterfeit determination. 

For example:

  • Wild cabbage the dissimilar looking structures have evolved from common ancestral design.
  • Wheat (many varieties obtained due to artificial selection)

Molecular Phylogeny:

  •  It depends on the possibility that adjustments in DNA during generation are the essential occasions in the advancement
  •  Organisms which are all the more indirectly related will collect more prominent contrasts in their DNA

Exercise Discussion of Xam Idea Class 10 Science Chapter 9 Heredity and Evolution

Very Short Answer Type Questions

In this section, you get 27 questions each containing 1 mark. The definition of mutation, what are fossils, what is genetic drift are some of the examples of the question which are there in this section.

Short Answer Type Questions Part-I

This section contains 12 questions and every question contains 2 marks. What is the cause of variations, what is the contribution of Mendel in genetics, how does use and disuse of an organ help in the evolution of a new species, etc are some of the examples of the question that are given in this section?

Short Answer Type Questions Part-II

In this section, you get 23 questions each of 3 marks. Describe the contribution of Lamarck, mention three important features of fossils which help in the study of evolution, how do variations occur in an offspring, etc are some of the examples of the question that are given in this section.

Long Answer Type Questions

In this section, you get only 12 questions each containing 5 marks. In this section check how much you understand the chapter. Here you have to answer every question in detail and the question is like, Explain the ways in which evolutionary relationships can be treated, Describe Darwin’s theory of evolution, What are the various evidence in favour of evolution, etc.

HOTS (Higher Order Thinking Skills)

There is a total of 6 questions in this section and all the questions are very important. These questions are given to you to check how much you read or understand the chapter. The reason why Mendel chose pea plants for his experiments, why is making antiviral drugs more difficult than making antibacterial medicines, etc are some of the examples of the question that are asked in this section.

Value-Based Questions

This section is given to you to check what values you learn from this chapter and how you would express your values in front of societies and different peoples.

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