Class 10 Science - CBSE
Heredity
The Chapter 'Heredity' in Class 10 CBSE Science explores how traits and characteristics are passed down from parents to offspring through generations. Students will learn about Gregor Mendel's groundbreaking experiments with garden peas, discovering the laws of inheritance, dominant and recessive traits, and how genes determine physical features. The chapter also covers sex determination in humans. This is a high-scoring and conceptually vital chapter for CBSE board exams, frequently featuring direct numerical ratio problems, diagram-based questions on monohybrid and dihybrid crosses, and conceptual applications that test your understanding of genetic variations.
Start Learning FreeKey Concepts
Heredity
The transmission of characters or traits from parents to their offspring, which is the primary reason why children resemble their parents.
Variations
The differences in traits and characteristics shown by individuals of the same species, which are essential for evolution and survival in changing environments.
Dominant and Recessive Traits
A dominant trait is expressed even when only one copy is present (e.g., Tallness), while a recessive trait is expressed only when two identical copies are present (e.g., dwarfness).
Genotype and Phenotype
Genotype is the genetic makeup of an organism (e.g., TT, Tt), whereas phenotype is the observable physical appearance or trait (e.g., Tall plant).
Monohybrid Cross
A cross between two parents that studies the inheritance of a single pair of contrasting traits, resulting in a 3:1 phenotypic ratio in the F2 generation.
Sex Determination in Humans
The process by which biological sex is determined; humans have 23 pairs of chromosomes, where the 23rd pair (XX in females, XY in males) determines whether the child is a boy or a girl.
Important Formulas
Board Exam Info
In the CBSE Class 10 Science board exam, the Heredity and Evolution unit usually carries around 4 to 7 marks. Heredity specifically contributes 3 to 5 marks. Expect questions ranging from 1-mark MCQs, 2-mark definitions/reasons, to 3-mark analytical problems where you must draw a Punnett square or predict offspring ratios from a given cross.
Frequently Asked Questions
What is the difference between acquired and inherited traits?
Inherited traits are genetic changes passed from parents to offspring (like eye color) and affect DNA. Acquired traits are developed during a lifetime (like learning to ride a bicycle) and do not affect germ cells, so they cannot be inherited.
How is the sex of a child determined in human beings?
Human females have XX chromosomes and produce eggs with X. Males have XY chromosomes and produce two types of sperm: 50% with X and 50% with Y. If a sperm carrying X fertilizes the egg, it's a girl (XX); if Y fertilizes the egg, it's a boy (XY).
Why did Mendel choose garden pea plants for his experiments?
Mendel chose garden peas because they have many distinct contrasting characters, are easy to grow, have a short life span, and naturally self-pollinate but can also be easily cross-pollinated artificially.
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