Class 10 Science Chapter 8 Heredity

  • Home
  • Class 10 Science Chapter 8 Heredity
ptitle-particle2
ptitle-particle1

[ays_quiz id=”53″]

Class 10 → Science → Chapter 8: Heredity

I. Chapter Summary:

Heredity is the process by which traits are passed from parents to offspring. This chapter explains how variations arise during reproduction and how traits are inherited through genes. It introduces the pioneering work of Gregor Mendel, who explained inheritance patterns using pea plants. The chapter covers concepts like dominant and recessive traits, genotype and phenotype, monohybrid and dihybrid crosses, and sex determination in humans. It also highlights the importance of heredity in evolution.

II. Key Concepts Covered:

1. Heredity and Variation

  • Heredity: Passing of traits from parents to offspring
  • Variation: Differences among individuals of the same species

2. Mendel’s Experiments

  • Conducted on pea plants
  • Established laws of inheritance
  • Traits are controlled by factors (genes)

3. Laws of Inheritance

Law of Dominance

  • One trait is dominant over another

Law of Segregation

  • Alleles separate during gamete formation

Law of Independent Assortment

  • Traits are inherited independently

4. Important Terms

  • Gene: Unit of heredity
  • Allele: Different forms of a gene
  • Genotype: Genetic makeup
  • Phenotype: Physical appearance

5. Monohybrid Cross

  • Involves one pair of contrasting traits
  • Ratio: 3:1 (dominant : recessive)

6. Dihybrid Cross

  • Involves two traits
  • Ratio: 9:3:3:1

7. Sex Determination in Humans

  • Males: XY
  • Females: XX
  • Father determines the sex of the child

8. Role of Heredity in Evolution

  • Variations help organisms adapt
  • Leads to evolution over time

III. Important Questions:

(A) MCQs (1 Mark)

  1. Who is known as the Father of Genetics?
    a) Darwin
    b) Mendel ✅
    c) Lamarck
    d) Watson
  2. Which trait is expressed in F1 generation?
    a) Recessive
    b) Dominant ✅
    c) Both
    d) None
  3. What is the ratio of a monohybrid cross?
    a) 1:1
    b) 3:1 ✅
    c) 9:3:3:1
    d) 2:1
  4. Who determines the sex of the child?
    a) Mother
    b) Father ✅
    c) Both equally
    d) Environment

(B) Short Answer Questions (2/3 Marks)

  1. Define heredity and variation.
  2. What are dominant and recessive traits?
  3. Explain Mendel’s law of segregation.
  4. What is genotype and phenotype?

(C) Long Answer Questions (5 Marks)

  1. Explain Mendel’s monohybrid cross with an example.
  2. Describe the dihybrid cross and its ratio.
  3. Explain sex determination in humans with diagram.
  4. Discuss the importance of variation in evolution.

(D) HOTS Questions

  1. Why do identical twins show slight differences despite having the same genes?
  2. How would the absence of genetic variation affect survival of species?

IV. Key Formulas / Concepts:

Monohybrid Cross Ratio:

  • Phenotypic Ratio = 3 : 1

Dihybrid Cross Ratio:

  • Phenotypic Ratio = 9 : 3 : 3 : 1

Sex Determination:

  • XX → Female
  • XY → Male

V. Deleted Portions (CBSE 2025–2026):

  • Detailed Mendelian experiments with complex examples
  • Some extended pedigree analysis problems

VI. Chapter-Wise Marks Bifurcation (Estimated – CBSE 2025–2026):

Unit/Chapter Estimated Marks Type of Questions Typically Asked
Heredity 6–8 Marks MCQs, Case-based, Short & Long Answer

⚠️ Note: This is an estimate. Actual marks may vary.

VII. Previous Year Questions (PYQs):

1 Mark

  • Define gene. (CBSE 2020)

2/3 Marks

  • Explain dominant and recessive traits. (CBSE 2019)

5 Marks

  • Explain monohybrid cross with diagram. (CBSE 2022)

VIII. Real-World Application Examples:

  • Medical Genetics: Understanding genetic diseases
  • Agriculture: Hybrid crops with better yield
  • Forensics: DNA fingerprinting
  • Family Traits: Eye color, height inheritance

IX. Student Tips & Strategies for Success:

Time Management

  • Practice genetic crosses daily
  • Revise ratios and definitions

Exam Preparation

  • Draw Punnett squares neatly
  • Focus on diagrams and ratios

Stress Management

  • Stay calm during problem solving
  • Practice regularly instead of memorizing

X. Career Guidance & Exploration (Class 10):

Science Stream Careers

  • Geneticist
  • Doctor
  • Biotechnologist

Relevant Entrance Exams:

  • NEET
  • JEE

XI. Important Notes:

  • Refer to CBSE updates regularly
  • Practice NCERT questions thoroughly
  • Focus on concept clarity + diagrams
  • Solve previous year questions

Create your account

[ct-user-form form_type="register"]