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NCERT Books for Class 10 Science Chapter 9

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NCERT Books for Class 10 Science - Heredity and Evolution - Free PDF Download

NCERT Books for Class 10 Science Chapter 9 is a critical and high-scoring chapter, as many problems from it will feature in the CBSE Term II exams. Students will gain a thorough understanding of the ideas based on the CBSE board's most recent syllabus. Vedantu provides free PDF solutions that may be accessed at any time to assist students with the exercise-by-exercise answers. It also expedites syllabus revision a few days before the exam. Students can get a free PDF of NCERT Solutions for Class 10 Science by clicking on the link.

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Topics in the Chapter

Topics in the Chapter

The topics discussed in this chapter are listed below-

  1. Accumulation of Variation During Reproduction

  2. Evolution

    1. Acquired and Inherited Traits

  3. Evolution and Classification

    1. Evolution by Stages

    2. Tracing Evolutionary Relationships

    3. Fossils

  4. Speciation

  5. Evolution Should Not Be Equated With ‘Progress'

    1. Human Evolution

  6. Heredity

    1. How do these Traits get Expressed?

    2. Inherited Traits

    3. Mendel’s Contributions

    4. Sex Determination


Mind Map


Variation accumulation during Reproduction

  • During reproduction, characters, features, and qualities are passed down from generation to generation.

  • This inheritance supplies the next generation with both a shared fundamental body design and minor alterations.

  • When this generation reproduces, the children will inherit both inherited and newly developed differences from the preceding generation.

  • Variations in a population occur as a result of the accumulation of these differences from generation to generation.

  • Different variations offer different benefits to the population, and the variation that offers the best chances of survival is passed down to the following generation.


Heredity

  • The transmission of features from parent to offspring via genes in the chromosomes is referred to as heredity.

  • Contributions of Mendel

  • Mendel was the first scientist whose research led to the development of inheritance laws.

  • He explored the transmission of features with two contrasting traits, such as round/wrinkled seeds, tall/short plants, white/violet flowers, and so on, in cross-hybridization tests of the garden pea plant (Pisum sativum).


Determination of sex

  • Different animals employ various techniques to accomplish this:

  • The temperature at which fertilised eggs are stored, for example, impacts the sex of developing creatures in the eggs. Crocodiles, turtles, and other animals have been observed to have it.

  • Snails may alter their gender, suggesting that sex is not defined by genetics.

  • Humans, for example, have a genetically defined sex.


Evolution

  • It refers to the gradual change in population characteristics (plants and animals) over successive generations.

  • Evolution is explained by errors in DNA copying during reproduction, mutations, and natural selection.

  • Evolution creates biodiversity at every level of biological organisation, including species, people, molecules, and so on.


'Progress' Should Not Be Associated With Evolution

  • Evolution is simply the generation and shaping of diversity through environmental selection.

  • The only apparent progressive trend in evolution appears to be the formation of increasingly complex body forms throughout time. However, this does not imply that previous designs are ineffective.

  • Bacteria, for example, live in the most inhospitable environments, such as hot springs, deep-sea thermal vents, and ice in Antarctica.


Human Evolution

  • Tools have been employed to investigate human evolution, including excavating, time-dating, and examining fossils, determining DNA sequences, and so on.

  • Regardless of skin colour or the human race, all people are a single species.

  • Homo sapiens, the oldest members of the human species, may be traced back to Africa, implying that we are all descended from Africans.

  • Some of our forefathers departed Africa a few hundred thousand years ago, while others remained.

  • The migrants migrated gradually throughout the globe, from Africa to West Asia, then to Central Asia, Eurasia, South Asia, and East Asia.

  • They traveled down the Indonesian and Philippine islands to Australia, then across the Bering land bridge to the Americas.

FAQs on NCERT Books for Class 10 Science Chapter 9

1. How to download Class 10 Science Chapter 9 NCERT Book for CBSE?

Students can download it from NCERT official website. On this page, Students can download Class 10 Science Chapter-9 PDF Solutions of the Book.

2. What does the word Speciation mean? 

It's a gradual evolutionary process in which populations develop into different species.


In the process of speciation, reproductive and geographical isolation are crucial factors. Genetic drift occurs when the frequency of an existing gene variant in a population changes.


Genetic drift, combined with natural selection, results in the development of new species over generations.


Other causes that can cause speciation include sudden severe DNA changes (mutation), such as chromosomal number alterations, and variance, such as female green beetles refusing to mate with male red beetles. Her actions secure reproductive isolation between them, resulting in the emergence of new species. It's a gradual evolutionary process in which populations develop into different species.


In the process of speciation, reproductive and geographical isolation are crucial factors. 

3. In Chapter 9 of the NCERT book for Class 10 Science, what are similar organs?

Analogous organs are organs from different animals that perform similar activities. The structural appearance of these organs may differ, but their functions are the same in all creatures. While answering textbook questions, students can refer to Chapter 9  to acquire a better understanding of the ideas. There are topic-by-topic and exercise-by-exercise options available for students to use based on their needs. You can find further answers in the books and solutions of class 10 Science NCERT which are easily available for free on the Vedantu website. Also, one can find the answers readily available in the Vedantu app that can be downloaded from the Google Play Store. 

4. What are the topics that are covered in the Chapter 9 of the class 10 NCERT Science book?

The topics in Chapter 9 are as follows:

  • Accumulation of Variation During Reproduction

  • Evolution

    • Acquired and Inherited Traits

  • Evolution and Classification

    • Evolution by Stages

    • Tracing Evolutionary Relationships

    • Fossils

  • Speciation

  • Evolution Should Not Be Equated With ‘Progress'

    • Human Evolution

  • Heredity

    • How do these Traits get Expressed?

    • Inherited Traits

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

    • Sex Determination

5. Why shouldn’t progress be associated with Human Evolution?

Progress should not be associated with human evolution because of the following given reasons:

  • Evolution is simply the generation and shaping of diversity through environmental selection.

  • The only apparent progressive trend in evolution appears to be the formation of increasingly complex body forms throughout time. However, this does not imply that previous designs are ineffective.

  • Bacteria, for example, live in the most inhospitable environments, such as hot springs, deep-sea thermal vents, and ice in Antarctica.

6. How are Evolution and classification interlinked?

Classification is the process of grouping organisms into useful categories based on plainly observable characteristics. Cell type (prokaryote or eukaryote), single-cell or multicellular, presence or lack of a nucleus, autotrophic (such as photosynthesis) or heterotrophic, sexual or asexual reproduction, and other characteristics are used to categorise organisms. The more features two species share, the more closely related they are. And the closer they are linked, the more recent a common ancestor they will have had. A brother and sister, for example, are more closely related than a female and her first cousin.