Class 10 Science Chapter 8: Heredity – NCERT Solutions Notes Heredity is an important biology chapter in Class 10 Science that explains how traits are passed from parents to offspring. It also introduces the basics of genetics, Mendel’s experiments, and the idea of evolution. These notes are designed for clear understanding and quick NCERT-based revision. Key Concepts Heredity Heredity is the transmission of traits from parents to offspring. Variation Differences in traits among individuals of the same species. Importance: Helps in survival Supports evolution Mendel’s Experiments Gregor Mendel studied heredity using pea plants. Why pea plants? Short life cycle Clear contrasting traits Easy to grow Mendel’s Monohybrid Cross A cross involving one pair of contrasting traits. Example: Tall (T) × Dwarf (t) Results: F1 generation: all tall plants F2 generation: 3 tall : 1 dwarf Mendel’s Dihybrid Cross A cross involving two traits. Example: Seed shape + seed colour Dominant and Recessive Traits Dominant trait: expressed in F1 generation Recessive trait: hidden in F1, appears in F2 Genes and DNA Gene A unit of heredity that controls traits. DNA Genetic material present in chromosomes. Chromosomes Structures in the nucleus that carry genes. Humans have 23 pairs of chromosomes. Sex Determination in Humans Females: XX Males: XY Male determines the sex of the child. Inherited Traits and Evolution Small changes in genes over generations lead to evolution. Acquired Traits vs Inherited Traits Acquired Traits Inherited Traits Developed during lifetime Passed from parents Not genetic Genetic Not passed to offspring Passed to offspring NCERT Important Questions (Concept Based) What is heredity? Transmission of traits from parents to offspring. What is a gene? A unit of heredity controlling a trait. Why is variation important? It helps organisms survive changing environments. Important Diagrams to Revise Monohybrid cross chart Dihybrid cross Chromosome structure Sex determination (XX–XY) Why this chapter is important This chapter is very important for exams and is frequently asked in: Genetic cross problems Definitions Diagrams NCERT reasoning questions Final Revision Tip Focus on: Mendel’s experiments Dominant vs recessive traits Monohybrid cross (very important) Sex determination Difference between acquired and inherited traits