Heredity is the transmission of characteristics from parents to offspring through genes carried on chromosomes. Gregor Mendel’s experiments on pea plants laid the foundations: by tracking single traits (monohybrid crosses) and pairs of traits (dihybrid crosses), he showed that traits are controlled by factors (genes) that come in dominant and recessive forms. A dominant trait appears even when only one copy is present, while a recessive trait shows only when both copies are recessive. Mendel’s ratios — 3:1 in the F₂ generation of a monohybrid cross and 9:3:3:1 in a dihybrid cross — reveal how traits separate and recombine independently. The chapter also explains sex determination in humans, where the father’s X or Y chromosome decides the sex of the child, while the mother always contributes an X chromosome.
Mendel’s experimentsDominant and recessive traitsMonohybrid and dihybrid crossesSex determination in humansGenes and inheritance
Key terms
Gene
A unit of heredity that controls a particular trait.
Dominant trait
A trait expressed even when only one allele is present.
Recessive trait
A trait expressed only when both alleles are recessive.
Sex determination
How the sex of offspring is decided by sex chromosomes.
Extra questions & answers
QUESTIONS
Activity 8.1
Activity 8.2
QUESTIONS
EXERCISES
Try one from this chapter
Who is regarded as the “Father of Genetics” for his work on pea plants?
Flashcards & interactive practice
Practice quiz · Heredity
Score on this chapter, climb the leaderboard, and get an AI diagnosis of your mistakes.
Double-checked questions Real exam pattern 1 free test every month, then ₹9 per test
#1
Heredity
Start here
Science 10 Qs · ~10 min
Instant score, answer review and weak-topic diagnosis
Data & insights
Trending in Class 10 this weekThe chapters students are reading most right now
