Reproduction in Plants
Overview
Where does a new plant come from? From a seed. Where does the seed come from? From a flower. This chapter covers plant reproduction — the method without seeds (asexual) and the method involving flowers and seeds (sexual).
Typed Notes
Without seeds — asexual reproduction
(1) Vegetative propagation — a new plant grows from the vegetative parts of a plant (stem, root, or leaf): from the 'eyes' (buds) of a potato, from the nodes of ginger; cuttings (branches) of rose or gulmohar are placed in water or soil — they develop roots — and a new plant grows (this is how gardeners make new plants of their favourite varieties); from the roots of sweet potato and dahlia; on the edges of bryophyllum leaves, new plants sprout. (2) Budding — in yeast: a small outgrowth (bud) appears on the body — it grows — then breaks off to become a new yeast organism. (3) Fragmentation — in spirogyra (green algae): it breaks apart — each piece becomes a new organism. (4) Spore formation — in mushroom, fern, and bread mould: light spores travel through the air — wherever they find a moist place — a new organism grows. Advantages: fast, only one parent needed, offspring have the same qualities.
Parts of a flower — male and female
The main reproductive parts of a flower are: (1) Stamen — male part: filament (stalk) + anther (at the top — contains pollen grains — yellow and powdery — these are the male gametes). (2) Carpel/Pistil — female part: stigma (at the top — sticky — catches pollen), style (stalk), ovary (at the bottom — contains ovules inside — each ovule has an egg/female gamete). Other parts: sepals (green — protect the bud), petals (colourful — attract insects). The flower is the reproduction centre of the plant.
Pollination — the journey of pollen
The transfer of pollen from the anther to the stigma is called pollination. There are two types: (1) Self-pollination — pollen from the anther of the same flower lands on its own stigma (as in pea). (2) Cross-pollination — pollen from one flower reaches the stigma of another flower — agents: insects (bees and butterflies — attracted by colourful petals and nectar — pollen sticks to their bodies), wind (very light pollen in large quantities — as in grass and maize), and water (in some aquatic plants). Cross-pollination produces plants with new traits — creating variety.
From fertilisation to seed
When pollen lands on the stigma — a pollen tube forms inside — it travels through the style into the ovary — inside, it meets the egg — fertilisation occurs → zygote is formed. The zygote grows and develops into an embryo; the ovule becomes a seed (embryo + food + seed coat); the ovary becomes a fruit (which contains the seed inside). The seed falls to the ground — in moist soil with sunlight — it germinates — and a new plant grows. This is the cycle: flower → seed → new plant → flower again.
Key Concepts
Revision ke liye ek nazar — exam se pehle yahi padhna hai.
- 01Asexual reproduction: only one parent, a new organism comes from it — without flowers or seeds. Types: vegetative propagation (from stem/root/leaf), budding (yeast), fragmentation (spirogyra), spore formation (mushroom, fern).
- 02Vegetative propagation: stem — potato (eyes), ginger, rose (cutting); root — sweet potato, dahlia; leaf — bryophyllum (new plants grow on the edges of leaves).
- 03Sexual reproduction: the male part of the flower (stamen — anther → pollen) and the female part (carpel — stigma, style, ovary → ovule/egg).
- 04Pollination: pollen travels from the anther to the stigma — self-pollination (same flower) or cross-pollination (another flower — agents: insects, wind, water).
- 05Fertilisation: pollen + egg → zygote → seed (embryo). Ovary → fruit, ovule → seed. A new plant grows from the seed.
Questions & Solutions
Pehle khud try karo — phir solution kholo. Yahi tariqa topper banata hai.
What is vegetative propagation? Give three examples.
What is the difference between self-pollination and cross-pollination?
Name and describe the parts of the stamen and carpel.
What is the relationship between a seed and a fruit?
How are budding and fragmentation different from each other?
What role do insects play in cross-pollination?
Asexual (one parent, no seeds): vegetative propagation (potato/rose/bryophyllum), budding (yeast), fragmentation (spirogyra), spores (mushroom). Sexual: stamen (pollen) + carpel (ovary and egg); pollination (self/cross — insects and wind) → fertilisation → zygote → seed; ovary → fruit. Seed → new plant.
Chapter-end quiz
4 MCQsOption tap karo — turant pata chalega sahi ya galat, explanation ke saath.
Q1.In bryophyllum, where do new plants grow from?
Q2.Where are pollen grains produced?
Q3.What does pollination mean?
Q4.What does the ovary become after fertilisation?
Mark karo — dashboard par progress dikhega.