Class 9 · ScienceNCERT 2026 Revised Syllabus
Chapter 11: Reproduction: How Life Continues (0906CH11)
Exploration · Asexual and sexual reproduction, pollination, fertilisation, human reproduction.
Chapter code: 0906ch11 · Book: Exploration · Class 9 Science
Find complete NCERT solutions for Class 9 Science, Exploration Chapter 11. Every question has a clear, step-by-step answer for chapter code 0906CH11.
Pause and Ponder(11 questions)
1
In a china-rose (hibiscus or gudhal) plant, a pollen tube grows and continues through the style after pollen lands on the stigma. Which process is about to happen next?
School Level Solution
Ans.
The pollen tube is growing toward the ovule. The next major step is fertilisation, in which the male gamete delivered by the pollen tube fuses with the female gamete in the ovule.
2
Look at the pictures (Fig. 11.16) of calotropis (madar) seeds and dandelion seeds. Can you guess what kind of seed dispersal these seeds are adapted for?
School Level Solution
Ans.
Both are adapted for wind dispersal. Their light seeds and hair-like/feathery structures increase drag and allow the wind to carry them away from the parent plant.
3
A farmer plants two varieties of maize side by side, but notices that seeds form only when pollen from one variety reaches the stigma of the other. What type of pollination is this?
School Level Solution
Ans.
Pollen is transferred from one plant to another plant of the same species, so it is cross-pollination.
4
Why do animals with external fertilisation generally produce more eggs than animals with internal fertilisation?
School Level Solution
Ans.
In external fertilisation, eggs are released into the environment and are more exposed to currents, predators and other losses. Producing many eggs increases the probability that some are successfully fertilised and survive.
5
In animals, which fertilisation method protects the gametes more?
School Level Solution
Ans.
In internal fertilisation, the gametes meet inside the female body, where they are better protected from environmental conditions and predators.
6
Ravi is growing taller, his voice is changing and reproductive organs are maturing. What stage of life is he experiencing?
School Level Solution
Ans.
These are characteristic changes of adolescence/puberty, when reproductive organs mature and the body undergoes rapid physical changes.
7
Rina had her first menstrual period on 5 March. If her cycle is approximately 28 days, on what date would her next period be expected?
School Level Solution
Ans.
A 28-day interval after 5 March gives approximately 2 April.
8
A zygote is formed by fusion of a sperm and an egg in humans. How many chromosomes does the zygote have?
School Level Solution
Ans.
A human sperm and egg each carry 23 chromosomes. Fusion restores the diploid number: 23 + 23 = 46.
9
Why are protective devices such as condoms important in reproductive health?
School Level Solution
Ans.
Condoms act as a barrier that can reduce the chance of sperm reaching the egg and can also reduce transmission of many sexually transmitted infections.
10
Oral contraceptive pills can help prevent pregnancy. What risk remains if they are used without condoms?
School Level Solution
Ans.
Oral contraceptive pills can prevent ovulation and pregnancy but do not provide a barrier against sexually transmitted infections. Condoms provide STI protection in addition to contraception.
11
Why are human babies dependent on adults for a long period after birth compared with many other animals?
School Level Solution
Ans.
Human babies require prolonged care because many physical, behavioural and cognitive capacities continue developing after birth. Adults provide food, protection, warmth and learning support for an extended period.
Activities — How to Do(7 questions)
1
Activity 11.1 (cutting, grafting, layering): observe gardeners/farmers performing these three techniques and record the steps. What is each technique in one line?
School Level Solution
Ans.
Cutting: a stem piece is cut and planted to root independently. Grafting: a scion (desired shoot) is joined onto a stock (rooted stem) so tissues fuse. Layering: a still-attached twig is bent into soil to root before separation. Record each step observed.
2
Activity 11.2 (yeast budding): activate yeast in warm sugar solution, mount a drop after 1–2 hours, and observe under the microscope. What should you see, and what does it prove?
School Level Solution
Ans.
After incubation, slides show round cells with smaller outgrowths (buds) attached. The bud enlarges, receives a copied nucleus, and detaches as a new cell — visible proof of asexual reproduction by budding in yeast.
3
Activity 11.3 (bread mould): keep moistened bread/roti in a warm dark moist chamber; inspect daily; after 3 days mount some mould with cotton-blue stain. What growth and structures do you expect?
School Level Solution
Ans.
White/grey cottony patches spread over 3 days (faster in warmth + moisture). Stained mounts reveal branching hyphae tipped with round sporangia full of spores — the fungus feeds on bread and reproduces by spores. Draw and label both.
4
Activity 11.4 (bead model of segregation): take three different-coloured bead pairs; build combinations picking one bead per pair. How many combinations, and what does scaling to 23 pairs imply?
School Level Solution
Ans.
Three pairs give 2 × 2 × 2 = 8 combinations. Scaling up: 23 chromosome pairs give 2²³ ≈ 84 lakh gamete types from assortment alone — showing why independent assortment makes every individual (except identical twins) genetically unique.
5
Activity 11.5 (flower parts): collect different flowers; observe whorls outer to inner; record in Table 11.1; cut ovary sections and draw. What should the table and drawings capture?
School Level Solution
Ans.
For each flower record calyx (sepals), corolla (petals), androecium (stamens), gynoecium (carpels) — number and arrangement. Ovary T.S. shows chambers/ovules; L.S. shows style–stigma–ovary continuity. Functions: protection, attraction, male/female reproduction.
6
Activity 11.6 (pea pollination): emasculate selected buds/flowers, bag them with muslin, leave one flower open, and compare pod formation. What do the results in Table 11.2 prove?
School Level Solution
Ans.
Emasculated + bagged flowers form no pods (no pollen reached them); open flowers set pods normally. The muslin bags act as controls, proving fruit needs pollination — and emasculation prevents self-pollination in breeding experiments.
7
Activity 11.7 (pollen vs seed data): wind-pollinated grasses release 5–10 lakh pollen for 50–200 seeds; insect-pollinated sunflower releases 20–40 thousand for 800–1000 seeds. Compare ratios and justify huge pollen output.
School Level Solution
Ans.
Pollen-to-seed ratio: grasses ≈ 5000:1 (5,00,000 ÷ 100); sunflower ≈ 30:1. Wind delivery is random and wasteful, so sheer numbers guarantee hits; insects deliver precisely, so fewer grains suffice. Huge output is the price of an unguided vector.