CLASS XII BIOLOGY
REPRODUCTION IN ORGANISMS
Detailed Chapter Notes — NCERT Biology, Unit: Reproduction
Topics Covered
● Characteristics and significance of reproduction
● Asexual reproduction — modes, fission, budding, fragmentation, spore formation, vegetative
propagation
● Sexual reproduction — pre-fertilisation, fertilisation, post-fertilisation events
● Reproduction in flowering plants — flower structure, gametogenesis, pollination, fertilisation
● Reproduction in humans (overview) — male and female reproductive systems
● Key terms, diagrams described, comparison tables, and exam-oriented Q&A
Compiled as structured revision notes suitable for board exam preparation, quick revision, and moot-style precision in
definitions.
, 1. Introduction to Reproduction
Reproduction is the biological process by which living organisms produce new individuals ('offspring') that
are similar to themselves. It is essential for continuation of species, though not essential for survival of an
individual organism.
1.1 Characteristics of Reproduction
● Life span: The time between birth and natural death of an organism. It varies greatly — mango tree
may live for 100 years while some insects live only for a few days.
● Reproductive events differ across organisms but the end result — production of progeny — is the
same.
● A well-defined life span is required for a species to reproduce and perpetuate.
1.2 Types of Reproduction
Basis Asexual Reproduction Sexual Reproduction
Gametes involved No fusion of gametes Fusion of male and female gametes
(fertilisation)
Number of parents Single parent Usually two parents (some exceptions)
Genetic variation Offspring genetically identical (clones) Offspring genetically variable
Speed Faster, simpler Relatively slower, more complex
Examples Amoeba, Hydra, Yeast, Bryophyllum Humans, most animals and flowering
plants
NCERT Focus: Asexual reproduction is common in single-celled organisms, and in plants and simple
animals; sexual reproduction is seen in higher plants and animals.
REPRODUCTION IN ORGANISMS
Detailed Chapter Notes — NCERT Biology, Unit: Reproduction
Topics Covered
● Characteristics and significance of reproduction
● Asexual reproduction — modes, fission, budding, fragmentation, spore formation, vegetative
propagation
● Sexual reproduction — pre-fertilisation, fertilisation, post-fertilisation events
● Reproduction in flowering plants — flower structure, gametogenesis, pollination, fertilisation
● Reproduction in humans (overview) — male and female reproductive systems
● Key terms, diagrams described, comparison tables, and exam-oriented Q&A
Compiled as structured revision notes suitable for board exam preparation, quick revision, and moot-style precision in
definitions.
, 1. Introduction to Reproduction
Reproduction is the biological process by which living organisms produce new individuals ('offspring') that
are similar to themselves. It is essential for continuation of species, though not essential for survival of an
individual organism.
1.1 Characteristics of Reproduction
● Life span: The time between birth and natural death of an organism. It varies greatly — mango tree
may live for 100 years while some insects live only for a few days.
● Reproductive events differ across organisms but the end result — production of progeny — is the
same.
● A well-defined life span is required for a species to reproduce and perpetuate.
1.2 Types of Reproduction
Basis Asexual Reproduction Sexual Reproduction
Gametes involved No fusion of gametes Fusion of male and female gametes
(fertilisation)
Number of parents Single parent Usually two parents (some exceptions)
Genetic variation Offspring genetically identical (clones) Offspring genetically variable
Speed Faster, simpler Relatively slower, more complex
Examples Amoeba, Hydra, Yeast, Bryophyllum Humans, most animals and flowering
plants
NCERT Focus: Asexual reproduction is common in single-celled organisms, and in plants and simple
animals; sexual reproduction is seen in higher plants and animals.
