Why is variation beneficial to a species but not always to an individual?
Answer framework: Explain environmental change, population diversity and differential survival.
All Class 10 Science notes
Chapter 7 • Biology
How do Organisms Reproduce?
Study DNA copying, asexual and sexual reproduction, human reproductive systems, reproductive health and contraception.
Core concepts checklist
Importance of reproduction and variation
Fission, budding, fragmentation, regeneration and spores
Vegetative propagation
Sexual reproduction in flowering plants
Human reproduction, contraception and reproductive health
Formula & fact bank
DNA copying → variation → survival advantage
Pollination → fertilisation → zygote → embryo → seed
Testes → sperm; ovaries → ova
Contraception: barrier, hormonal, IUCD and surgical methods
Diagrams to practise
Draw with pencil, use straight label lines, add arrows and write a precise caption.
- 1Binary fission in Amoeba
- 2Longitudinal section of flower
- 3Male reproductive system
- 4Female reproductive system
CBSE examiner focus
- Do not confuse pollination with fertilisation
- Connect DNA-copy variation to evolution without claiming every variation is useful
- Present contraception answers scientifically and sensitively
Board-style practice
Describe fertilisation and development in flowering plants.
Answer framework: Trace pollen transfer, tube growth, male gamete fusion, zygote, embryo, seed and fruit formation.
Turn revision into marks with Eduvista
Use this guide for recall, then practise timed answers and get feedback. Eduvista combines visual notes, NCERT clarity, board-pattern tests and personal doubt support.