🌸 How Do Organisms Reproduce?
Sexual Reproduction in Plants | Class 10 Science | CBSE + Foundation + Competitive
How Do Organisms Reproduce? | Sexual Reproduction in Plants
1. Introduction – परिचय
English:
Sexual reproduction involves the formation of male and female gametes and their fusion to form a zygote. In flowering plants, the flower is the reproductive structure. Sexual reproduction produces variation because genetic material comes from two gametes.
हिन्दी:
लैंगिक जनन में नर तथा मादा युग्मकों का निर्माण और उनका संलयन शामिल होता है, जिससे युग्मनज (zygote) बनता है। आवृतबीजी पौधों में फूल जनन संरचना है।
Sexual reproduction involves the formation of male and female gametes and their fusion to form a zygote. In flowering plants, the flower is the reproductive structure. Sexual reproduction produces variation because genetic material comes from two gametes.
हिन्दी:
लैंगिक जनन में नर तथा मादा युग्मकों का निर्माण और उनका संलयन शामिल होता है, जिससे युग्मनज (zygote) बनता है। आवृतबीजी पौधों में फूल जनन संरचना है।
2. Flower – The Reproductive Organ
A typical flower contains four main whorls:
- Calyx – sepals
- Corolla – petals
- Androecium – male reproductive part
- Gynoecium – female reproductive part
🌸 Animated Structure of a Flower
3. Male Reproductive Part – Stamen
The stamen is the male reproductive part of a flower.
It consists mainly of:
- Filament – stalk that supports the anther.
- Anther – produces pollen grains.
4. Female Reproductive Part – Pistil/Carpel
The pistil or carpel is the female reproductive part.
It has three main parts:
After fertilisation:
Ovule → Seed
Ovary → Fruit
| Part | Function |
|---|---|
| Stigma | Receives pollen grains |
| Style | Connects stigma with ovary and provides a pathway for pollen tube growth |
| Ovary | Contains ovules |
Ovule → Seed
Ovary → Fruit
5. Bisexual and Unisexual Flowers
| Type | Meaning | Example |
|---|---|---|
| Bisexual flower | Contains both stamens and carpels | Hibiscus, mustard |
| Unisexual flower | Contains either stamens or carpels | Papaya, watermelon |
6. Pollination – परागण
Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
There are two major types:
- Self-pollination
- Cross-pollination
7. Self-Pollination
Self-pollination occurs when pollen reaches the stigma of the same flower or another flower on the same plant.
It does not require pollen transfer between different plants.
Same Flower / Same Plant → Pollen Transfer → Stigma
8. Cross-Pollination
Cross-pollination occurs when pollen grains are transferred from a flower of one plant to the stigma of a flower on another plant of the same species.
Agents such as insects, wind and other animals may help in pollination.
Plant A → Pollen → Plant B → Stigma
9. Agents of Pollination
| Agent | Typical Feature |
|---|---|
| Wind | Light, dry pollen; exposed anthers/stigmas in many wind-pollinated flowers |
| Insects | Flowers may have colour, scent and nectar |
| Animals | Can transfer pollen while visiting flowers |
10. Pollen Tube Formation
After a compatible pollen grain lands on the stigma, it can germinate and produce a pollen tube.
The pollen tube grows through the style towards the ovary.
It carries the male gametes towards the ovule.
🌱 Animated Pollen Tube Growth
11. Fertilisation – निषेचन
Fertilisation is the fusion of male and female gametes to form a zygote.
In flowering plants, male gametes are delivered through the pollen tube to the ovule.
The male gamete fuses with the female gamete (egg cell).
Male Gamete + Female Gamete → Zygote
12. Double Fertilisation – द्विनिषेचन
A special feature of flowering plants is double fertilisation.
One male gamete fuses with the egg to form the diploid zygote.
The other male gamete fuses with the two polar nuclei to form the triploid primary endosperm nucleus.
Therefore:
Syngamy:
Male gamete + Egg → Zygote (2n)
Triple fusion:
Male gamete + Two polar nuclei → Primary endosperm nucleus (3n)
Syngamy:
Male gamete + Egg → Zygote (2n)
Triple fusion:
Male gamete + Two polar nuclei → Primary endosperm nucleus (3n)
Competitive/Foundation Point:
Double fertilisation is characteristic of flowering plants (angiosperms). It involves syngamy + triple fusion.
Double fertilisation is characteristic of flowering plants (angiosperms). It involves syngamy + triple fusion.
13. What Happens After Fertilisation?
| Before Fertilisation | After Fertilisation |
|---|---|
| Ovule | Seed |
| Ovary | Fruit |
| Zygote | Embryo |
| Fertilisation | Seed formation begins |
14. Seed Formation
After fertilisation, the zygote develops into an embryo.
The ovule develops into a seed.
The seed contains the embryo and stored food in varying forms depending on the plant.
Under suitable conditions, the seed germinates to produce a new plant.
Zygote → Embryo → Seed → Germination → New Plant
15. Fruit Formation
After fertilisation, the ovary develops into the fruit.
The wall of the ovary generally develops into the pericarp, which forms the fruit wall.
Fruits protect seeds and help in their dispersal.
16. Seed Germination
When a viable seed receives suitable conditions such as water, oxygen and appropriate temperature, it may germinate.
The embryo resumes growth.
The radicle generally develops into the primary root and the plumule develops into the shoot.
Seed + Water + Oxygen + Suitable Temperature
→ Germination → Seedling
17. Sexual Reproduction Produces Variation
Sexual reproduction involves genetic material from two gametes.
During sexual reproduction, genetic combinations can differ among offspring.
Therefore, sexual reproduction generates variation.
Variation is important for adaptation and evolution of populations.
18. Advantages of Sexual Reproduction in Plants
- Produces genetic variation.
- Variation may help populations adapt to changing environments.
- Creates new combinations of characteristics.
- Supports evolution over generations.
19. Sexual vs Asexual Reproduction
| Feature | Sexual Reproduction | Asexual Reproduction |
|---|---|---|
| Gametes | Involved | Generally not involved |
| Fertilisation | Occurs | Absent |
| Parents | Genetic material from two gametes | Usually one parent |
| Variation | More genetic variation | Generally less variation |
| Example in plants | Flowering plants producing seeds | Vegetative propagation |
20. Complete Sequence – Flowering Plant Reproduction
Flower
↓
Anther Produces Pollen
↓
Pollination
↓
Pollen Germination
↓
Pollen Tube Growth
↓
Male Gametes Reach Ovule
↓
Fertilisation
↓
Zygote
↓
Embryo
↓
Seed
↓
Germination
↓
New Plant
21. 30 MCQs – MCQ Practice
Q1. The reproductive structure of a flowering plant is:
A) Flower
B) Root
C) Leaf
D) Stem
Answer: A) Flower
Q2. The male reproductive part of a flower is:
A) Pistil
B) Stamen
C) Ovary
D) Stigma
Answer: B) Stamen
Q3. Pollen grains are produced in:
A) Filament
B) Stigma
C) Anther
D) Ovary
Answer: C) Anther
Q4. The female reproductive part of a flower is:
A) Anther
B) Filament
C) Stamen
D) Pistil/Carpel
Answer: D) Pistil/Carpel
Q5. The stigma mainly functions to:
A) Receive pollen grains
B) Produce ovules
C) Produce seeds
D) Store food
Answer: A) Receive pollen grains
Q6. Ovules are present inside the:
A) Anther
B) Ovary
C) Filament
D) Stigma
Answer: B) Ovary
Q7. Transfer of pollen from anther to stigma is called:
A) Fertilisation
B) Germination
C) Pollination
D) Fragmentation
Answer: C) Pollination
Q8. Pollination between flowers of two different plants of the same species is:
A) Self-pollination
B) Budding
C) Vegetative propagation
D) Cross-pollination
Answer: D) Cross-pollination
Q9. The tube formed by a germinating pollen grain is called:
A) Pollen tube
B) Root tube
C) Seed tube
D) Ovule tube
Answer: A) Pollen tube
Q10. The pollen tube generally grows through the:
A) Anther
B) Style
C) Petal
D) Sepal
Answer: B) Style
Q11. Fusion of male and female gametes produces:
A) Seed
B) Fruit
C) Zygote
D) Pollen
Answer: C) Zygote
Q12. Double fertilisation is characteristic of:
A) Fungi
B) Algae
C) Bryophytes
D) Flowering plants
Answer: D) Flowering plants
Q13. Syngamy results in the formation of:
A) Zygote
B) Endosperm
C) Pollen tube
D) Fruit wall
Answer: A) Zygote
Q14. Triple fusion produces:
A) Zygote
B) Primary endosperm nucleus
C) Embryo
D) Seed coat
Answer: B) Primary endosperm nucleus
Q15. The ovule develops into:
A) Fruit
B) Pollen
C) Seed
D) Petal
Answer: C) Seed
Q16. After fertilisation, the ovary generally develops into:
A) Seed
B) Embryo
C) Pollen tube
D) Fruit
Answer: D) Fruit
Q17. The zygote develops into:
A) Embryo
B) Pollen grain
C) Stigma
D) Anther
Answer: A) Embryo
Q18. A flower containing both stamens and carpels is:
A) Unisexual
B) Bisexual
C) Sterile
D) Vegetative
Answer: B) Bisexual
Q19. Which is an example of a unisexual flower?
A) Hibiscus
B) Mustard
C) Papaya
D) Rose
Answer: C) Papaya
Q20. Which is an example of a bisexual flower?
A) Papaya
B) Watermelon
C) Maize
D) Hibiscus
Answer: D) Hibiscus
Q21. The stalk of the stamen is called:
A) Filament
B) Style
C) Stigma
D) Ovule
Answer: A) Filament
Q22. Which structure connects stigma and ovary?
A) Filament
B) Style
C) Anther
D) Sepal
Answer: B) Style
Q23. Which process introduces greater genetic variation?
A) Binary fission
B) Budding
C) Sexual reproduction
D) Vegetative propagation
Answer: C) Sexual reproduction
Q24. Which is NOT normally a requirement for seed germination?
A) Water
B) Oxygen
C) Suitable temperature
D) Fertilisation at the time of germination
Answer: D) Fertilisation at the time of germination
Q25. The male gametes in flowering plants are delivered to the ovule through:
A) Pollen tube
B) Sepal
C) Petal
D) Filament
Answer: A) Pollen tube
Q26. The triploid product of triple fusion is:
A) Zygote
B) Primary endosperm nucleus
C) Embryo
D) Pollen grain
Answer: B) Primary endosperm nucleus
Q27. Which combination is correct?
A) Anther — receives pollen
B) Ovary — produces pollen
C) Ovule — develops into seed
D) Filament — contains ovules
Answer: C) Ovule — develops into seed
Q28. Which structure usually becomes the fruit after fertilisation?
A) Ovule
B) Stigma
C) Anther
D) Ovary
Answer: D) Ovary
Q29. Which sequence is correct?
A) Pollination → Pollen tube → Fertilisation → Seed
B) Fertilisation → Pollination → Pollen tube → Seed
C) Seed → Pollination → Fertilisation → Flower
D) Pollen tube → Pollination → Seed → Fertilisation
Answer: A) Pollination → Pollen tube → Fertilisation → Seed
Q30. The main biological significance of sexual reproduction is:
A) No variation
B) Generation of variation
C) Absence of gametes
D) Absence of fertilisation
Answer: B) Generation of variation
22. 30 Subjective Questions
2 Marks
Q1. What is sexual reproduction?
Answer: Sexual reproduction involves the formation of male and female gametes and their fusion to form a zygote.
2 Marks
Q2. Name the male and female reproductive parts of a flower.
Answer: The male reproductive part is the stamen and the female reproductive part is the pistil/carpel.
2 Marks
Q3. What is pollination?
Answer: Pollination is the transfer of pollen grains from the anther to the stigma.
2 Marks
Q4. What is fertilisation?
Answer: Fertilisation is the fusion of male and female gametes to form a zygote.
2 Marks
Q5. What happens to the ovule and ovary after fertilisation?
Answer: The ovule develops into a seed and the ovary generally develops into a fruit.
3 Marks
Q6. Describe the structure of a stamen.
Answer: A stamen consists of a filament and anther. The filament supports the anther. The anther produces pollen grains containing male reproductive cells.
3 Marks
Q7. Describe the structure of a pistil.
Answer: The pistil consists of stigma, style and ovary. The stigma receives pollen, the style provides a path for the pollen tube and the ovary contains ovules.
3 Marks
Q8. Differentiate self-pollination and cross-pollination.
Answer: Self-pollination involves pollen transfer within the same flower or same plant. Cross-pollination involves transfer from one plant to another plant of the same species.
3 Marks
Q9. What is a bisexual flower? Give one example.
Answer: A bisexual flower contains both stamens and carpels. Hibiscus is an example.
3 Marks
Q10. What is a unisexual flower? Give one example.
Answer: A unisexual flower contains either stamens or carpels. Papaya is an example.
4 Marks
Q11. Explain the process of pollination.
Answer: Pollen grains produced in the anther are transferred to the stigma. This transfer may occur within the same flower/plant or between different plants of the same species. Wind, insects and animals can act as pollinating agents.
4 Marks
Q12. Explain pollen tube formation.
Answer: After a compatible pollen grain lands on the stigma, it germinates and forms a pollen tube. The tube grows through the style towards the ovary and carries male gametes to the ovule.
4 Marks
Q13. Explain the changes that occur after fertilisation.
Answer: The zygote develops into an embryo. The ovule becomes a seed and the ovary generally becomes a fruit. The seed contains the developing embryo and stored food.
4 Marks
Q14. Differentiate bisexual and unisexual flowers.
Answer: Bisexual flowers contain both stamens and carpels, e.g. hibiscus. Unisexual flowers contain either stamens or carpels, e.g. papaya.
4 Marks
Q15. Explain the role of stigma, style and ovary.
Answer: Stigma receives pollen grains. Style connects stigma to ovary and supports pollen tube growth. Ovary contains ovules and after fertilisation generally develops into a fruit.
5 Marks
Q16. Draw and explain the structure of a typical flower.
Answer: A typical flower has sepals, petals, stamens and carpels. Stamen consists of filament and anther. Carpel consists of stigma, style and ovary. The ovary contains ovules.
5 Marks
Q17. Explain sexual reproduction in flowering plants.
Answer: The anther produces pollen grains. Pollination transfers pollen to the stigma. A pollen tube develops and grows through the style to the ovule. Male gametes reach the female gamete and fertilisation occurs. The zygote forms an embryo, while ovule becomes seed and ovary becomes fruit.
5 Marks
Q18. Explain double fertilisation.
Answer: In flowering plants, one male gamete fuses with the egg to form the diploid zygote. The other male gamete fuses with two polar nuclei to form the triploid primary endosperm nucleus. These two fusion events constitute double fertilisation.
5 Marks
Q19. Explain the importance of sexual reproduction.
Answer: Sexual reproduction creates new combinations of genetic material and produces variation. Variation can help organisms adapt to changing environments and contributes to evolution.
5 Marks
Q20. Explain seed formation and germination.
Answer: After fertilisation, the ovule develops into a seed containing an embryo. Under suitable conditions of water, oxygen and temperature, the embryo resumes growth. The radicle forms the root and the plumule forms the shoot.
6 Marks
Q21. Describe sexual reproduction in a flowering plant from pollination to seed formation.
Answer: Pollen grains are transferred from anther to stigma. A compatible pollen grain germinates and forms a pollen tube. The tube grows through the style and reaches the ovule. Male gametes are delivered to the female gamete. Fertilisation forms a zygote. The zygote develops into an embryo and the ovule develops into a seed.
6 Marks
Q22. Explain the male and female reproductive parts of a flower.
Answer: The stamen is the male part and consists of filament and anther. The anther produces pollen grains. The pistil/carpel is the female part and consists of stigma, style and ovary. The ovary contains ovules.
6 Marks
Q23. Explain double fertilisation with equations.
Answer: Syngamy: Male gamete + egg → diploid zygote. Triple fusion: Male gamete + two polar nuclei → triploid primary endosperm nucleus. Together these processes are called double fertilisation and are characteristic of flowering plants.
6 Marks
Q24. Explain self-pollination and cross-pollination and compare them.
Answer: Self-pollination occurs within the same flower or plant. Cross-pollination occurs between different plants of the same species. Cross-pollination generally promotes greater genetic mixing, whereas self-pollination tends to maintain greater genetic similarity.
6 Marks
Q25. Explain the changes in flower parts after fertilisation.
Answer: The zygote develops into an embryo. The ovule becomes a seed and the ovary becomes a fruit. Other floral parts may wither and fall, although the exact fate of accessory floral parts can vary among plants.
6 Marks
Q26. Explain why sexual reproduction leads to variation.
Answer: Sexual reproduction involves genetic material from two gametes. Their combination creates new genetic combinations. Therefore, offspring can differ from their parents and from one another, producing variation.
6 Marks
Q27. Explain the importance of pollinating agents.
Answer: Pollinating agents such as wind, insects and animals transfer pollen from anther to stigma. This transfer enables pollen germination and subsequent fertilisation in flowering plants.
6 Marks
Q28. Explain the complete sequence of sexual reproduction in flowering plants.
Answer: Flower formation → pollen production → pollination → pollen germination → pollen tube growth → male gamete delivery → fertilisation → zygote → embryo → seed → germination → new plant.
6 Marks
Q29. Differentiate sexual and asexual reproduction.
Answer: Sexual reproduction involves gametes and fertilisation and produces greater genetic variation. Asexual reproduction generally involves one parent without gamete fusion and usually produces offspring genetically similar to the parent.
6 Marks
Q30. Explain the role of sexual reproduction in adaptation and evolution.
Answer: Sexual reproduction produces genetic variation. Some variations may provide advantages under changing environmental conditions. Such advantageous variations can become more common over generations, contributing to adaptation and evolution.
23. CBSE Golden Points ⭐
⭐ Flower → reproductive structure of flowering plants.
⭐ Stamen → male reproductive part.
⭐ Anther → produces pollen grains.
⭐ Pistil/Carpel → female reproductive part.
⭐ Stigma → receives pollen.
⭐ Style → pathway for pollen tube.
⭐ Ovary → contains ovules.
⭐ Pollination → transfer of pollen from anther to stigma.
⭐ Fertilisation → fusion of male and female gametes.
⭐ Zygote → develops into embryo.
⭐ Ovule → Seed.
⭐ Ovary → Fruit.
⭐ Double fertilisation → Syngamy + Triple fusion.
⭐ Sexual reproduction → genetic variation.
⭐ Stamen → male reproductive part.
⭐ Anther → produces pollen grains.
⭐ Pistil/Carpel → female reproductive part.
⭐ Stigma → receives pollen.
⭐ Style → pathway for pollen tube.
⭐ Ovary → contains ovules.
⭐ Pollination → transfer of pollen from anther to stigma.
⭐ Fertilisation → fusion of male and female gametes.
⭐ Zygote → develops into embryo.
⭐ Ovule → Seed.
⭐ Ovary → Fruit.
⭐ Double fertilisation → Syngamy + Triple fusion.
⭐ Sexual reproduction → genetic variation.
24. One-Line Revision 🧠
🌸 Flower → Reproductive Organ
♂ Stamen → Male Part
🟡 Anther → Pollen
♀ Pistil → Female Part
🎯 Stigma → Receives Pollen
🌿 Style → Pollen Tube Path
🥚 Ovary → Ovules
🌬️ Pollination → Pollen Transfer
🔗 Fertilisation → Gamete Fusion
🌱 Ovule → Seed
🍎 Ovary → Fruit
🧬 Sexual Reproduction → Variation
25. Important Diagram Questions
1. Draw and label a typical flower.
2. Label anther and filament.
3. Label stigma, style and ovary.
4. Draw pollen tube growth through the style.
5. Explain pollination with a diagram.
6. Explain fertilisation in flowering plants.
7. Draw and explain double fertilisation.
8. Show conversion of ovule into seed and ovary into fruit.
2. Label anther and filament.
3. Label stigma, style and ovary.
4. Draw pollen tube growth through the style.
5. Explain pollination with a diagram.
6. Explain fertilisation in flowering plants.
7. Draw and explain double fertilisation.
8. Show conversion of ovule into seed and ovary into fruit.
26. Super-Fast Memory Trick 🚀
S → A → P → S → O → F → S
Stamen → Anther → Pollen → Stigma → Ovule → Fertilisation → Seed
Stamen → Anther → Pollen → Stigma → Ovule → Fertilisation → Seed
O → F
Ovary → Fruit
O → S
Ovule → Seed
Ovary → Fruit
O → S
Ovule → Seed
Syngamy + Triple Fusion = Double Fertilisation
27. Final Exam Revision
Complete Process:
Anther
↓
Pollen
↓
Pollination
↓
Stigma
↓
Pollen Tube
↓
Ovule
↓
Male Gamete + Female Gamete
↓
Zygote
↓
Embryo
↓
Seed
↓
Germination
↓
New Plant
Most Important Conversion:
Ovule → Seed | Ovary → Fruit
Most Important Competitive Point:
Double Fertilisation = Syngamy + Triple Fusion
