Reproduction In Plants Class 7 Chapter Notes

Key points

• Reproduction is the process by which living organisms produce new individuals of their own kind.
• Plants reproduce by two main methods: asexual reproduction and sexual reproduction.
• In asexual reproduction, only one parent is involved and seeds are not formed; examples include potato, rose, yeast and Bryophyllum.
• In sexual reproduction, male and female reproductive cells join to form a new plant; in flowering plants, the flower is the reproductive part.
• The stamen is the male part of a flower and produces pollen grains in the anther.
• The pistil or carpel is the female part; it has stigma, style and ovary containing ovules.
• Pollination means transfer of pollen grains from anther to stigma; fertilisation means fusion of male and female gametes.
• After fertilisation, the ovary develops into a fruit and the ovule develops into a seed.
• Seed dispersal prevents overcrowding and helps plants spread to new places.
• Agents of seed dispersal include wind, water, animals and bursting of fruits.

Important definitions

Reproduction

The biological process by which living organisms produce new individuals of the same kind.

Asexual reproduction

A mode of reproduction in which a new plant is produced from a single parent without formation of seeds.

Sexual reproduction

A mode of reproduction in which male and female gametes fuse to form a new individual.

Vegetative propagation

A type of asexual reproduction in which new plants grow from vegetative parts such as roots, stems, leaves or buds.

Budding

Asexual reproduction in which a small outgrowth called a bud develops on the parent and later separates to form a new individual, as in yeast.

Pollination

Transfer of pollen grains from the anther to the stigma of a flower.

Fertilisation

Fusion of the male gamete with the female gamete to form a zygote.

Zygote

The single cell formed after fusion of male and female gametes; it develops into an embryo.

Seed dispersal

The scattering of seeds away from the parent plant by agents like wind, water, animals or explosion of fruits.

Big idea: how plants make new plants

Plants cannot move from place to place like animals, but they have smart ways to continue their species. In asexual reproduction, a plant can produce a new plant from a body part such as a stem, root, leaf or bud. This is fast and does not need flowers, pollen or seeds. In sexual reproduction, flowers produce male and female reproductive cells. The pollen grain carries the male cell, and the ovule contains the female cell. When pollen reaches the stigma, it may form a pollen tube that carries the male gamete to the ovule. After fertilisation, the zygote develops into an embryo, the ovule becomes a seed, and the ovary becomes a fruit. Therefore, the correct flow to remember is: flower → pollination → fertilisation → seed and fruit formation → seed dispersal → germination.

Asexual reproduction in plants: quick revision

Asexual reproduction vs sexual reproduction

Sexual reproduction in a flowering plant: step-by-step

1. 1. Flower produces reproductive cells — The anther of the stamen produces pollen grains containing male gametes. The ovary of the pistil contains ovules with female gametes.
2. 2. Pollination occurs — Pollen grains are transferred from anther to stigma. This may happen by wind, water, insects or other animals.
3. 3. Pollen tube grows — After reaching a suitable stigma, a pollen grain forms a pollen tube through the style towards the ovule.
4. 4. Fertilisation takes place — The male gamete fuses with the female gamete inside the ovule to form a zygote.
5. 5. Seed and fruit form — The zygote develops into an embryo. The ovule becomes a seed and the ovary becomes a fruit.
6. 6. Seed dispersal and germination — Seeds are dispersed away from the parent plant. Under suitable air, water and warmth, a seed germinates into a new plant.

Self-pollination vs cross-pollination

Worked mini-examples

• {"title":"Example 1: Potato tuber","bodyMarkdown":"Q: A potato piece with an eye grows into a new plant. Which type of reproduction is it? A: Vegetative propagation. The eye is a bud on the stem tuber, so a new plant grows from a vegetative part, not from a seed."}
• {"title":"Example 2: From flower to fruit","bodyMarkdown":"Q: In a mango flower, what does the ovary become after fertilisation? A: The ovary becomes the fruit. The ovule becomes the seed. This is a very common one-mark exam question."}
• {"title":"Example 3: Seed dispersal clue","bodyMarkdown":"Q: A seed has wings or hair-like structures and is light in weight. What is its likely dispersal agent? A: Wind. Examples include maple-like winged seeds and cotton-like hairy seeds."}

Seed dispersal: why it is important

If all seeds fell directly below the parent plant, many seedlings would grow in the same small area. They would compete for sunlight, water, minerals and space. Seed dispersal solves this problem by spreading seeds to different places. Wind-dispersed seeds are often light or winged; water-dispersed seeds can float, like coconut; animal-dispersed seeds may be fleshy, edible, sticky or spiny; and some fruits burst open suddenly to throw seeds away. In answers, always connect seed dispersal with two ideas: reducing competition and colonising new areas.

Exam tip: common traps in this chapter

Do not write pollination and fertilisation as the same process. Pollination is only transfer of pollen, while fertilisation is fusion of gametes. Remember the exact conversion after fertilisation: ovary → fruit and ovule → seed. For vegetative propagation, mention the plant part and example together, such as potato-stem tuber, Bryophyllum-leaf buds, rose-stem cutting. In diagrams, label anther, filament, stigma, style and ovary clearly; incomplete labels often lose marks.

Quick revision checks

• Q: What is the main difference between asexual and sexual reproduction in plants? A: Asexual reproduction involves one parent and no seeds; sexual reproduction involves fusion of gametes and usually forms seeds.
• Q: Name the male and female reproductive parts of a flower. A: The male part is the stamen; the female part is the pistil or carpel.
• Q: What is pollination? A: Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
• Q: Why is seed dispersal useful? A: It prevents overcrowding near the parent plant and helps plants grow in new places.

Frequently Asked Questions