ScienceCBSE Class 10 · How do Organisms Reproduce?

Sexual Reproduction in Flowering Plants

Updated 14 October 2026 · Fact-checked

In flowering plants, the stamen (male part) makes pollen and the pistil (female part) holds ovules in its ovary. Pollen reaches the stigma by pollination, a pollen tube grows down the style, and the male germ cell fuses with the egg in the ovule. The zygote becomes an embryo, the ovule a seed and the ovary a fruit.

Understand Sexual Reproduction in Flowering Plants

Why sexual reproduction? DNA copying is not perfectly accurate, so variation builds up slowly. Sexual reproduction speeds up variation by combining DNA from two individuals, creating new combinations. To stop the DNA doubling every generation, special cells (germ cells or gametes) carry half the number of chromosomes and half the DNA of body cells, made by a cell division called meiosis. When two gametes fuse, the original number is restored in the zygote. In complex organisms one gamete is large with food stores (female) and the other small and usually motile (male).

The flower. The reproductive parts of angiosperms are in the flower: sepals, petals, stamens and pistil. The stamens and pistil carry the germ cells.

A flower with either stamens or pistil is unisexual (papaya, watermelon); one with both is bisexual (Hibiscus, mustard).
The stamen is the male part; its anther produces yellowish pollen grains.
The pistil, in the centre, is the female part: the swollen base is the ovary, the long middle part is the style, and the tip, which may be sticky, is the stigma. The ovary contains ovules, each with an egg cell.

Pollination. Pollen must be transferred from the stamen (anther) to the stigma. Transfer within the same flower is self-pollination; from one flower to another is cross-pollination, carried by agents such as wind, water or animals.

Fertilisation. After pollen lands on a suitable stigma, the pollen grain sends out a pollen tube, which grows down through the style until it reaches the ovary. The male germ cell produced by the pollen grain fuses with the female gamete (egg) in the ovule. This fusion is fertilisation, and it forms the zygote.

After fertilisation.

Repeated divisions of the zygote build an embryo inside the ovule.
The ovule forms a hard protective coat and turns into a seed.
The ovary grows rapidly and ripens into a fruit.
Petals, sepals, stamens, style and stigma may shrivel and fall off (some flower parts can persist in the fruit).

Germination. The seed contains the future plant, the embryo, which develops into a seedling under suitable conditions. Soak Bengal gram (chana) overnight, keep it moist for a day and cut it open: you can see the parts of the embryo, including the plumule (future shoot), radicle (future root) and cotyledons (food stores).

Pollination vs fertilisation. Pollination is the transfer of pollen to the stigma; fertilisation is the fusion of male and female gametes inside the ovule. Pollination comes first and is needed for fertilisation, but it is not the same event.

Sexual Reproduction in Flowering Plants: formulas and key facts

Pistil: $stigma + style + ovary (with ovules)$; Female reproductive part.
Stamen: $anther (pollen) + filament$; Male reproductive part.
Sequence of events: $pollination \to pollen tube \to fertilisation \to zygote \to embryo$; Then ovule → seed, ovary → fruit.
Chromosome number: $gamete = \frac{1}{2} \times body cell; zygote = gamete + gamete$; Halving by meiosis keeps the number constant across generations.

How to solve Sexual Reproduction in Flowering Plants questions

Most questions here ask for the sequence of events, a labelled flower diagram, or a comparison. Use this approach.

1Identify the stage asked about: flower parts, pollination, fertilisation, post-fertilisation changes or germination.
2Name the male (stamen: anther, pollen) and female (pistil: stigma, style, ovary, ovule, egg) parts with their roles.
3Describe pollination as transfer of pollen to the stigma; say whether self or cross and name the agent.
4Trace the pollen tube from stigma through style to ovary and ovule; state fusion of gametes forms the zygote.
5Give the fate of each part: zygote → embryo, ovule → seed, ovary → fruit; other parts may wither.
6For the L.S. of a flower diagram, label sepal, petal, stamen (anther, filament), stigma, style, ovary, ovule.

Sexual Reproduction in Flowering Plants in real life

Each concept, met in an everyday situation. Read the situation, try the problem, then check the solution. The one-line hook is what to remember.

Cross-pollination and fruit formation

Suppose a farmer grows papaya, which has unisexual flowers. He notices that some trees with flowers never set fruit, and that fruit-setting falls in a season when few insects visit his farm.

Explain why some papaya trees may never bear fruit, why fewer insects can mean less fruit, and what happens inside a flower that does set fruit.

Try it first, then show the solutionSolution

Papaya flowers are unisexual: a flower has either stamens or a pistil. A tree bearing only stamen-flowers has no ovary to become a fruit.
For the pistil-flowers to set fruit, pollen must come from another flower: cross-pollination, carried by agents such as wind, water or animals like insects.
With fewer insects, less pollen reaches stigmas, so fewer flowers are fertilised.
In a pollinated flower, a pollen tube grows through the style to the ovule; the male germ cell fuses with the egg to form a zygote, the ovule becomes a seed and the ovary ripens into the fruit.

Answer: Trees with only male (stamen) flowers cannot form fruit; fewer insects means less cross-pollination and so fewer fertilised flowers. After fertilisation, the ovule becomes a seed and the ovary a fruit.

Memory hook: No pollen on the stigma, no seed in the fruit.

Tricks to remember Sexual Reproduction in Flowering Plants

Short memory aids. Say each one aloud once, then use it on a question the same day.

SSO: stigma-style-ovary
Top to bottom of the pistil: Stigma (sticky landing pad), Style (tube path), Ovary (ovule store).
Use it when: Labelling the pistil.
Ovule → Seed, Ovary → Fruit
'Small O' (ovule) gives the small seed; 'big O' (ovary) gives the big fruit.
Use it when: Post-fertilisation changes.
P before F
Pollination (Pollen Placed) before Fertilisation (Fusion).
Use it when: Distinguishing pollination from fertilisation.

Sexual Reproduction in Flowering Plants: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Pollination vs fertilisation · 2 marks · Very short answerBoard level

How is pollination different from fertilisation? State where each takes place.

Try it first, then show the solutionSolution

Pollination: transfer of pollen grains from the anther to the stigma; takes place on the stigma (1 mark).
Fertilisation: fusion of the male germ cell with the egg (female gamete), forming a zygote; takes place inside the ovule in the ovary (1 mark).

Answer: Pollination transfers pollen to the stigma; fertilisation is fusion of gametes in the ovule.

Example 2: Growth of the pollen tube · 3 marks · Short answerHarder board level

Describe what happens from the moment a pollen grain lands on a suitable stigma until a zygote is formed. Draw a diagram showing germination of pollen on the stigma.

Try it first, then show the solutionSolution

A pollen tube grows out of the pollen grain on the stigma (1 mark).
The tube travels through the style and reaches the ovary and an ovule; the male germ cell is carried to the egg (1 mark).
The male germ cell fuses with the egg: fertilisation, forming the zygote. Diagram labels: pollen grain, stigma, pollen tube, style, ovary, ovule, female germ cell (1 mark).

Answer: Pollen tube grows from stigma through style to ovule; gametes fuse to form the zygote.

Example 3: After fertilisation · 3 marks · Short answerHarder board level

List the changes that take place in a flower after fertilisation. What is the advantage of seed formation for the plant?

Try it first, then show the solutionSolution

Repeated divisions of the zygote form an embryo inside the ovule; the ovule gets a hard protective coat and turns into a seed (1 mark).
The ovary grows rapidly and ripens into a fruit; petals, sepals, stamens, style and stigma may shrivel and fall off (1 mark).
A seed contains the embryo protected by a tough coat, with food stored in cotyledons, so the future plant can wait until conditions suit germination and can be dispersed (1 mark).

Answer: Zygote → embryo, ovule → seed, ovary → fruit, other parts wither; seeds protect and store food for the embryo.

Example 4: Why gametes have half the DNA · 3 marks · Short answerHarder board level

(a) Why must germ cells have only half the number of chromosomes of body cells? (b) Name the process that achieves this. (c) Give one advantage of sexual reproduction over asexual reproduction.

Try it first, then show the solutionSolution

(a) If two full sets of DNA combined, each generation would have twice the DNA of the previous one, which would upset the control of the cellular apparatus; halving restores the normal amount in the zygote (1 mark).
(b) Meiosis (1 mark).
(c) It combines DNA from two individuals, producing new combinations of variations faster, which helps the species survive changing conditions (1 mark).

Answer: (a) To keep DNA content constant. (b) Meiosis. (c) Greater variation.

Example 5: Experiment on a flower · 3 marks · Short answerHOTS / competency

A student removes the stamens from a bisexual flower before its anthers open and covers it with a paper bag. Another flower on the same plant is left untouched. (a) Will the bagged flower produce a seed by self-pollination? Why? (b) What could be done to make it produce seeds? (c) What does the untouched flower act as in this experiment?

Try it first, then show the solutionSolution

(a) No. Its own stamens were removed, so it has no pollen of its own; the bag stops pollen from arriving by wind or insects (1 mark).
(b) Dust pollen from another flower onto its stigma by hand (cross-pollination), then re-cover it; fertilisation and seed formation can then follow (1 mark).
(c) A control, showing what normally happens when pollination is not prevented (1 mark).

Answer: (a) No, no pollen can reach the stigma. (b) Hand-pollinate with pollen from another flower. (c) Control.

Where students lose marks in Sexual Reproduction in Flowering Plants

The slips examiners see most often, and what to write instead.

Mistake: Treating pollination and fertilisation as the same
Both involve pollen.
Wrong working
Pollination is the fusion of pollen with the ovule.
Right working
Pollination is transfer of pollen to the stigma; fertilisation is fusion of the male germ cell with the egg.
Do this: Write the two definitions side by side.
Usually costs: 1-2 marks.
Mistake: Wrong fate of flower parts
Ovary and ovule are confused.
Wrong working
The ovary becomes the seed and the ovule becomes the fruit.
Right working
The ovule becomes the seed; the ovary becomes the fruit.
Do this: Use the 'small O, big O' trick.
Usually costs: 1 mark.
Mistake: Incomplete pistil labels
Students label only 'pistil'.
Wrong working
Pistil (one label).
Right working
Stigma, style, ovary, ovule labelled separately.
Do this: Label each part of the pistil and stamen.
Usually costs: 1 mark in diagram questions.
Mistake: Mixing unisexual and bisexual examples
Examples are memorised loosely.
Wrong working
Hibiscus is unisexual; papaya is bisexual.
Right working
Papaya and watermelon: unisexual. Hibiscus and mustard: bisexual.
Do this: Learn the two NCERT pairs together.
Usually costs: ½ to 1 mark.

Exam tips

Use the term 'pollen tube' and say it travels through the style; this is the key step examiners look for.
Practise the L.S. of a flower and the germination of pollen on stigma diagrams; both are NCERT figures.
For post-fertilisation changes, state what each part becomes in a list.
Link sexual reproduction to variation and meiosis when asked 'why sexual reproduction?'.
Name agents of cross-pollination as wind, water or animals; avoid unsupported specifics.

Practice questions on Sexual Reproduction in Flowering Plants

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
The anther contains:
(a) sepals (b) ovules (c) pistil (d) pollen grains
Hint
The anther is part of the stamen.
Answer
(d) pollen grains.
Q2 · 1 mark · Assertion-reasonBoard level
Assertion (A): Papaya and watermelon flowers are unisexual.
Reason (R): A unisexual flower contains either stamens or pistil, not both.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Compare with Hibiscus and mustard.
Answer
(a).
Q3 · 3 marks · Short answerHarder board level
Draw a labelled diagram of the longitudinal section of a flower and mark the male and female reproductive parts.
Hint
Seven to eight labels.
Answer
Labels: sepal, petal, stamen with anther and filament (male part), pistil with stigma, style and ovary containing ovules (female part), receptacle. Show stamens around the central pistil.
Q4 · 4 marks · Case-basedHOTS / competency
Read the passage and answer.
Suppose a class soaks Bengal gram seeds overnight, keeps them under a wet cloth for a day, then cuts them open and observes the parts inside.
(a) What is the process by which the embryo grows into a seedling called? (1 mark)
(b) Name the parts that will form the root and the shoot. (1 mark)
(c) The seed came from an ovule of a flower. Trace in order how an egg cell in that ovule became the embryo you see, naming the events. (2 marks)
Hint
Pollination, pollen tube, fertilisation, zygote, divisions.
Answer
(a) Germination. (b) Radicle (root) and plumule (shoot). (c) Pollen reached the stigma (pollination); a pollen tube grew through the style to the ovule; the male germ cell fused with the egg (fertilisation) to form a zygote; the zygote divided several times to form the embryo, while the ovule developed a tough coat and became the seed.
Q5 · 3 marks · Short answerHOTS / competency
Self-pollination needs no outside agent, yet many plants rely on cross-pollination by wind, water or animals. Using the idea of variation, suggest why cross-pollination can be an advantage to a plant species.
Hint
Whose DNA is combined in each case?
Answer
In cross-pollination, gametes come from two different plants, so the offspring combine variations from two individuals, producing more new combinations. Greater variation in the population increases the chance that some individuals survive if conditions change. Self-pollination combines gametes of the same plant, giving fewer new combinations.
Q6 · 3 marks · Short answerHarder board level
What are the functions of the stigma, style and ovary? What would happen if the style of a flower were cut off just after pollination?
Hint
The style is the path of the pollen tube.
Answer
Stigma: receives pollen (often sticky). Style: path through which the pollen tube grows to the ovary. Ovary: contains ovules with egg cells; becomes the fruit. If the style were cut off just after pollination, the pollen tube could not reach the ovary, so fertilisation would not occur and no seeds would form from that pollen.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Male reproductive part of a flower?Show answer
Stamen (anther produces pollen).
2.Three parts of the pistil?Show answer
Stigma, style and ovary.
3.What does the ovary become after fertilisation?Show answer
The fruit.
4.What is formed when the male germ cell fuses with the egg?Show answer
The zygote.
5.Give two bisexual flowers.Show answer
Hibiscus and mustard.
6.Process that halves the chromosome number in gametes?Show answer
Meiosis.

Sexual Reproduction in Flowering Plants: frequently asked questions

What is the difference between self-pollination and cross-pollination?

Self-pollination is transfer of pollen within the same flower; cross-pollination is transfer from one flower to another, by wind, water or animals.

How does fertilisation take place in flowering plants?

A pollen tube grows from the pollen grain on the stigma through the style to the ovule, where the male germ cell fuses with the egg to form a zygote.

What happens to the ovule and ovary after fertilisation?

The ovule develops a tough coat and becomes a seed; the ovary grows and ripens into a fruit.

What are unisexual and bisexual flowers?

Unisexual flowers have either stamens or pistil (papaya, watermelon); bisexual flowers have both (Hibiscus, mustard).

Why is sexual reproduction important?

It combines DNA from two individuals, creating more variation, which helps species survive in changing conditions.