Heredity and Evolution Class 10 Science — Revision Notes
This chapter explores how traits are inherited from parents to offspring through genes and DNA. Students learn about dominant and recessive traits, the wor
TL;DR: This chapter explores how traits are inherited from parents to offspring through genes and DNA. Students learn about dominant and recessive traits, th…
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
This chapter explores how traits are inherited from parents to offspring through genes and DNA. Students learn about dominant and recessive traits, the wor
Genes and Inheritance
- Gene is unit of heredity controlling a particular trait
- Dominant allele expresses trait when present with recessive allele
- Recessive allele expresses trait only when present with another recessive
- Homozygous: two identical alleles, Heterozygous: two different alleles
Mendels Laws
- Law of Segregation: alleles separate during gamete formation
- Law of Independent Assortment: different traits assort independently
- Test cross: heterozygous crossed with homozygous recessive
- Monohybrid cross: Aa x Aa produces 3:1 phenotypic ratio
Sex Determination
- Humans have 23 pairs of chromosomes including one pair of sex chromosomes
- Males: XY (Y from father), Females: XX
- Sex-linked traits: color blindness, hemophilia linked to X chromosome
- Sex determination occurs at fertilization
Evolution and Natural Selection
- Evolution: gradual change in species over long periods
- Natural selection: organisms better adapted survive and reproduce
- Evidence: fossil records, homologous structures, DNA similarities
- Speciation: formation of new species through divergent evolution
Key Terms
- Allele: Different form of a gene for a particular trait
- Phenotype: Observable characteristics of an organism
- Genotype: Genetic makeup of an organism
Frequently Asked Questions
How did Mendel explain inheritance?
Mendel proposed that traits are controlled by pairs of factors (genes/alleles). During reproduction, alleles separate and recombine in offspring following predictable ratios.
What is natural selection?
Natural selection is the process where organisms with traits better suited to environment survive and reproduce, passing beneficial traits to offspring over generations.
More Class 10 Science Revision Notes
- Chemical Reactions and Equations
- Acids Bases and Salts
- Metals and Non-metals
- Carbon and its Compounds
- Life Processes
- Control and Coordination
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