Short Intro

This chapter explains how living organisms reproduce and ensure continuity of life. Students learn about asexual and sexual reproduction in plants and animals, pollination, fertilisation, reproductive systems in humans, menstruation, pregnancy, and methods of birth control with detailed explanations and solved questions.

Quick Information Box

Topic	Details
Chapter Name	Reproduction: How Life Continues
Class	Grade 9
Subject	Science
Main Topics	Reproduction in Plants and Humans
Important Processes	Pollination, Fertilisation, Meiosis
Human Chromosomes	46
Gametes Chromosomes	23

Concepts Used (Topics Covered)

Asexual Reproduction
Budding and Spore Formation
Sexual Reproduction
Meiosis and Gamete Formation
Pollination and Fertilisation
Self and Cross Pollination
Flower Structure
Reproduction in Animals
Human Male Reproductive System
Human Female Reproductive System
Menstrual Cycle
Pregnancy and Childbirth
Contraceptive Methods
Sexually Transmitted Infections (STIs)

Important Formulas

Number of Chromosomes in Human Gametes
= 23
Number of Chromosomes in Human Body Cells
= 46
Fertilisation
Male Gamete + Female Gamete → Zygote
Menstrual Cycle Duration
≈ 28 days
Ovulation
Occurs approximately on Day 14

Questions & Step-by-step Solutions with Explanation

Q1. Artificial Pollination Experiment

Question:

A flower’s anthers are removed before maturity and pollen from another plant is dusted onto stigma. Which process is ensured?

Solution:

Pollen is transferred from one plant to another plant of same species.

Answer:

Cross-pollination

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Q2. Correct Sequence in Plant Reproduction

Given:

(i) Pollen germination on stigma
(ii) Fertilisation
(iii) Pollination
(iv) Formation of zygote

Solution:

First pollination occurs, then pollen germinates, fertilisation takes place, and finally zygote forms.

Correct Order:

(iii) → (i) → (ii) → (iv)

Q3. Assertion and Reason

Assertion:

The zygote formed after fertilisation immediately attaches to uterus wall.

Reason:

The uterus wall is always prepared to receive zygote.

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Also Read : NCERT Class 9 Maths Exercise 2.1 Solutions – Introduction to Linear Polynomials

Solution:

Zygote first divides repeatedly before implantation.

Uterus lining changes cyclically and is not always ready.

Answer:

(iv) A is false but R is true.

Q4. Why Asexual Reproduction Produces Identical Offspring

Solution:

Asexual reproduction involves only mitosis.

No fusion of gametes occurs.

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Therefore offspring receive identical genetic material from parent.

Answer:

Offspring are genetically identical because only mitotic division occurs.

Q5. Why Menstruation Stops During Pregnancy

Solution:

During pregnancy, uterus lining is needed to nourish embryo.

Therefore uterine lining is not shed.

Answer:

Menstruation stops because the uterus retains its thick lining for embryo development.

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Q6. Why Night Blooming Flowers are White

Solution:

White or light coloured flowers are easily visible at night.

This helps attract pollinators like moths and insects.

Answer:

Night flowers are light coloured to attract pollinators in darkness.

Q7. Why Vegetatively Propagated Plants are Vulnerable

Solution:

Vegetative propagation produces clones with little variation.

If disease affects one plant, all similar plants may be affected.

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Answer:

Lack of genetic variation makes them more vulnerable to diseases.

Q8. Effect of Only Self-pollination

Solution:

Self-pollination reduces genetic variation.

Over generations, adaptability decreases.

Answer:

Genetic diversity decreases due to lack of mixing of genes.

Q9. Method for Producing Identical Plants Quickly

Solution:

Vegetative propagation or tissue culture can be used.

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These methods produce clones rapidly.

Answer:

Vegetative propagation is suitable for producing identical plants quickly.

Q10. Pollen Germination Experiment

(i) Possible Hypotheses

Sugar concentration affects pollen germination.
Optimum sugar concentration gives maximum germination.

(ii) Parameters to Keep Constant

Temperature
Type of pollen
Time duration
Slide conditions
Quantity of solution

Q11. Type of Pollination

Tomato:

Self-pollination because stamens cover stigma.

Wheat:

Wind pollination

Also Read : Class 9 Maths Exercise 1.2 Solutions | Coordinate Geometry NCERT Solutions

Papaya:

Cross-pollination because male and female flowers are on different plants.

Q12. Apple Orchard Investigation

(i) Hypothesis

Bee pollination increases fruit yield.

(ii) Parameters

Presence of bees
Fruit setting
Fruit drop
Number of flowers

(iii) Data Analysis

Place B with beekeeping shows:

Higher fruit setting
Lower fruit drop

(iv) Inference

Pollinators increase successful pollination and crop yield.

Q13. Ovulation Claim

Statement:

“Ovulation always occurs on day 14.”

Solution:

This is not always correct.

Reasons:

Menstrual cycles vary among females.
Stress, illness, and hormones affect ovulation timing.

Answer:

The statement is incorrect.

Q14. Why External Fertilisation Produces Many Eggs

Solution:

Many eggs are destroyed or eaten in water.

Producing large numbers increases survival chances.

Answer:

External fertilisation requires many eggs due to low survival rate.

Q15. Which Fertilisation Gives More Protection

Solution:

Internal fertilisation protects gametes and embryo inside body.

Answer:

Internal fertilisation provides more protection.

Q16. Function of Flower Parts

Flower Part	Function
Sepal	Protects bud
Petal	Attracts pollinators
Stamen	Produces pollen
Pistil	Female reproductive part

Q17. Why Pollination is Necessary

Solution:

Pollination transfers pollen grains to stigma.

This enables fertilisation and seed formation.

Answer:

Pollination is essential for fruit and seed formation.

Q18. Human Male Reproductive System

Main Parts:

Testes
Scrotum
Vas deferens
Urethra
Penis

Function:

Production and transfer of sperm.

Q19. Human Female Reproductive System

Main Parts:

Ovary
Oviduct
Uterus
Cervix
Vagina

Function:

Production of eggs and development of foetus.

Q20. What Happens During Fertilisation

Solution:

Sperm fuses with egg in oviduct.

A zygote is formed.

Answer:

Fusion of male and female gametes forms zygote.

Q21. Menstrual Cycle Stages

Days	Process
1–5	Menstruation
6–14	Uterus lining rebuilds
14	Ovulation
15–28	Thickening of uterus lining

Q22. Why Condoms are Important

Solution:

Condoms prevent:

Pregnancy
Sexually transmitted infections

Also Read : NCERT Class 9 Maths Exercise 2.2 Solutions – Linear Polynomials

Answer:

Condoms act as protective barrier methods.

Q23. Difference Between Sperm and Egg

Feature	Sperm	Egg
Size	Small	Large
Number	Millions	Few
Movement	Motile	Non-motile

Q24. IVF Technique

Solution:

Fertilisation occurs outside body in laboratory dish.

Embryo is implanted into uterus.

Answer:

IVF helps couples facing fertility problems.

Common Mistakes

Confusing pollination with fertilisation
Mixing self-pollination and cross-pollination
Forgetting functions of flower parts
Confusing mitosis and meiosis
Incorrect understanding of menstruation cycle

Exam Tips

Draw labelled diagrams of flower and reproductive systems.
Learn definitions carefully.
Revise menstrual cycle stages regularly.
Remember differences between sperm and egg.
Practice assertion-reason questions.

Practice MCQs

1. Transfer of pollen to stigma is called:

A. Fertilisation
B. Pollination
C. Germination
D. Budding

Answer:

B. Pollination

2. Male reproductive part of flower:

A. Pistil
B. Ovary
C. Stamen
D. Ovule

Answer:

C. Stamen

3. Human gametes contain:

A. 46 chromosomes
B. 23 chromosomes
C. 92 chromosomes
D. 12 chromosomes

Answer:

B. 23 chromosomes

4. Fertilisation in frogs is generally:

A. Internal
B. External
C. Artificial
D. Vegetative

Answer:

B. External

5. Which method prevents STIs?

A. Copper-T
B. Oral pills
C. Condoms
D. Surgery

Answer:

C. Condoms

FAQ Section

Q1. What is reproduction?

It is the biological process through which organisms produce new individuals.

Q2. What is pollination?

Transfer of pollen grains from anther to stigma.

Q3. What is fertilisation?

Fusion of male and female gametes.

Q4. Why is meiosis important?

It reduces chromosome number to half in gametes.

Q5. What is menstruation?

Monthly shedding of uterine lining when fertilisation does not occur.

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