Who is the father of genetics?

Gregor Mendel is considered the father of genetics for his work on inheritance in pea plants.

Evolution is the gradual process by which species change over time through natural selection and adaptation.

Heredity is the transmission of characteristics from parents to offspring through genes.

4. What did Mendel's pea experiments demonstrate?

Mendel showed inheritance follows patterns:law of dominance(dominant traits mask recessive in F1) andlaw of segregation(alleles separate during gamete formation).

6. What is a monohybrid cross and what is the typical F2 ratio?

Monohybrid cross studies inheritance of one trait (e.g., T × t). Mendel observed F2 phenotypic ratio3:1(dominant:recessive).

9. How is sex determined in humans and in bees?

Humans: XY system (males XY, females XX). Bees: haplodiploidy — males from unfertilised haploid eggs, females from fertilised diploid eggs.

12. What was Lamarck's theory and why is it incorrect?

Lamarck proposed use & disuse and inheritance of acquired traits (e.g., giraffes stretching necks). It is incorrect because acquired changes are not generally passed genetically to offspring.

13. What is Darwin's theory of natural selection?

Natural selection: individuals with favourable variations survive & reproduce more, changing population over time (e.g., industrial melanism in peppered moths).

15. What is speciation and how does it occur?

Speciation is formation of new species, often due to reproductive isolation (e.g., geographic separation) leading to independent evolution and inability to interbreed.

16. How do fossils provide evidence for evolution?

Fossils (imprints, petrified remains) show past life forms and transitional fossils (e.g., Archaeopteryx) indicate evolutionary links between groups over geological time.

20. What is the molecular basis of heredity?

DNA is the hereditary material: double helix of nucleotides (A, T, G, C) with complementary base pairing (A–T, G–C) encoding genetic information.

21. Define haploid and diploid. Which division produces them?

Diploid (2n) = two sets of chromosomes (body cells); haploid (n) = one set (gametes).Meiosisproduces haploid gametes;mitosismaintains diploid status.

22. What is crossing-over and why is it important?

Crossing-over is exchange of chromosome segments between homologous chromosomes during meiosis (chiasma), generating genetic recombination and increasing variation.

23. What is a pedigree chart?

A pedigree chart traces inheritance of a trait across generations in a family using standard symbols (squares = male, circles = female, shaded = affected).

25. How does natural selection explain antibiotic resistance in bacteria?

Bacteria with random mutations allowing survival in antibiotics reproduce. Repeated antibiotic use selects resistant strains — an example of natural selection driven by human pressure.

Heredity & Evolution — Class 10 Science Notes

🔹 Key Concepts

Heredity: Transmission of traits from parents to offspring

Mendelian Laws: Law of Dominance, Law of Segregation, Law of Independent Assortment

Evolution: Change in species over generations via natural selection

Speciation: Formation of new species from existing ones

Adaptation: Traits enhancing survival in environment

Topic	Example	Key Points
Heredity	Pea Plants	Transmission of traits, Mendel’s experiments
Mendelian Laws	Monohybrid & Dihybrid crosses	Dominant & recessive traits, ratios
Evolution	Darwin’s finches	Natural selection, adaptation, speciation

Topic

Example

Key Points

Heredity

Pea Plants

Transmission of traits, Mendel’s experiments

Mendelian Laws

Monohybrid & Dihybrid crosses

Dominant & recessive traits, ratios

Evolution

Darwin’s finches

Natural selection, adaptation, speciation

🧮 Practice Questions

Define heredity. ➡ Show Answer

What is the Law of Segregation? ➡ Show Answer

Explain natural selection. ➡ Show Answer

Mendelian Genetics Variation Evolution Evidence

NCERT Class 10 — Heredity & Evolution

📘 Introduction

🔹 Key Concepts

📊 Chapter Summary Table

🧮 Practice Questions

1. What is heredity?

2. What is variation? Name its types.

3. Define gene, allele and their relation to chromosomes and DNA.

4. What did Mendel's pea experiments demonstrate?

5. Differentiate genotype and phenotype with examples.

6. What is a monohybrid cross and what is the typical F2 ratio?

7. What does a dihybrid cross show? State Mendel's law involved.

8. Explain dominance, codominance and incomplete dominance with examples.

9. How is sex determined in humans and in bees?

10. What are mutations? Give types and an example where a mutation is advantageous.

11. Define evolution.

12. What was Lamarck's theory and why is it incorrect?

13. What is Darwin's theory of natural selection?

14. What are selection pressures? Give examples.

15. What is speciation and how does it occur?

16. How do fossils provide evidence for evolution?

17. Differentiate homologous and analogous organs with examples.

18. What is adaptive radiation? Example.

19. What are genetic drift, founder effect and bottleneck?

20. What is the molecular basis of heredity?

21. Define haploid and diploid. Which division produces them?

22. What is crossing-over and why is it important?

23. What is a pedigree chart?

24. Give a brief account of sickle-cell anaemia as a genetic disorder.

25. How does natural selection explain antibiotic resistance in bacteria?

26. What is the modern synthesis of evolution?

27. What are homologous chromosomes?

28. Why is variation important for evolution?

29. Can some traits be inherited maternally? Explain briefly.

30. Why were Mendel's pea experiments ideal for studying inheritance?

31. What is a phylogenetic tree?

32. What are vestigial organs? Give examples.

33. What is the molecular clock concept?

34. What is artificial selection? How does it differ from natural selection?

35. What does the neutral theory of molecular evolution state?

36. How are fossils formed and dated?

37. Define gene pool and its importance.

38. List forms of reproductive isolation that can lead to speciation.

39. Name three types of natural selection and a brief example of each.

40. Differentiate microevolution and macroevolution.

41. What is cultural evolution and how is it different from biological evolution?

42. Give a brief overview of human evolution.

43. What is gene flow and its evolutionary effect?

44. What methods do scientists use to study evolution?

45. (Concept) What is fitness in evolution?

46. What is convergent evolution?

47. What are punctuated equilibrium and gradualism?

48. How do molecular similarities support evolutionary relationships?

49. Why is understanding evolution important?

50. Quick revision: High-yield points for Heredity & Evolution.