This MCQ module is based on: Reproduction: How Life Continues — NCERT Exercises
TOPIC 42 OF 50
Reproduction: How Life Continues — NCERT Exercises
🎓 Class 9
Science
CBSE
Theory
Ch 11 — Reproduction: How Life Continues
⏱ ~15 min
🌐 Language: [gtranslate]
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This assessment will be based on: Reproduction: How Life Continues — NCERT Exercises
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Chapter Summary
Chapter 11 explains how living organisms make sure their species continues across generations. The big ideas — DNA copying, variation, asexual and sexual reproduction, the workshop of the flower, and the journey from zygote to new offspring — are summarised below.
Why reproduce?Individuals die; the species lives on only because new individuals are produced. Reproduction also creates variation, which is the raw material of evolution.
DNA copyingEvery reproductive event begins with the parent's DNA being copied. Tiny copying errors give rise to variations in the offspring.
Asexual reproductionOne parent; offspring are genetically near-identical clones. Includes binary fission, multiple fission, fragmentation, regeneration, budding, spore formation and vegetative propagation.
Sexual reproductionTwo parents; haploid (n) gametes fuse to form a diploid (2n) zygote. Mixing of two genomes produces large variation.
FertilizationExternal (fish, frog) — fusion in water. Internal (reptiles, birds, mammals) — fusion inside the female body. Internal fertilization needs fewer gametes.
EmbryoRepeated division of the zygote produces an embryo, which differentiates into the various tissues and organs of the new individual.
Flower partsSepals (calyx), petals (corolla), stamens (anther + filament — male), pistil (stigma + style + ovary with ovules — female).
PollinationTransfer of pollen from anther to stigma. Self vs cross. Agents — wind, water, insects (and other animals).
Fertilization in plantsPollen tube grows from stigma down through style; male gametes fuse with the egg in the ovule.
After fertilizationZygote → embryo; ovule → seed; ovary → fruit. Other floral parts wither.
Reproduction in animalsFish/amphibians — external fertilization, larval stage. Reptiles/birds — internal fertilization, hard-shelled eggs. Mammals — internal fertilization, embryo develops in the uterus.
Variation & evolutionSexual reproduction creates new gene combinations every generation. Useful variations are selected by the environment, leading to evolution over time.
Keyword Grid
ReproductionProducing new individuals of the same kind.
DNAGenetic blueprint inside the cell.
VariationGenetic differences among offspring.
AsexualOne parent; clones produced.
Binary FissionParent splits into two — Amoeba.
Multiple FissionMany daughter cells at once — Plasmodium.
FragmentationFilament breaks — Spirogyra.
RegenerationLost parts regrow — Hydra, Planaria.
BuddingOutgrowth on parent — yeast, Hydra.
SporesTough air-borne reproductive cells — Rhizopus.
Vegetative PropagationNew plant from root/stem/leaf.
GameteHaploid reproductive cell — sperm/egg.
Zygote2n cell formed at fertilization.
EmbryoMulticellular developing stage.
FertilizationFusion of male and female gametes.
StamenMale part — anther + filament.
PistilFemale part — stigma + style + ovary.
PollinationPollen transfer to stigma.
Pollen TubeCarries male gametes to ovule.
SeedFertilized ovule with embryo.
FruitRipened ovary surrounding seeds.
Bisexual FlowerBoth stamens and pistil — hibiscus.
Unisexual FlowerOnly male or only female — papaya.
External FertilizationOutside body — fish, frog.
Internal FertilizationInside body — mammal, bird.
NCERT Exercises — Step-by-Step Solutions
Click "Show Solution" to view the worked answer. Attempt each question on your own first.
Q 1 What is the importance of reproduction for a species?
Every individual organism has a finite lifespan. Without reproduction, the death of older individuals would not be balanced by the birth of new ones, and the species would disappear in a single generation.Reproduction therefore ensures the continuity of the species. Additionally, copying errors and mixing of genes during reproduction produce variations, which give the species the ability to adapt and evolve when the environment changes.
Q 2 Why is variation beneficial to a species but not necessarily to the individual?
An individual has a fixed body and lifestyle; a chance variation may or may not help that one individual — it may even be harmful.For the species, however, having a pool of varied individuals is insurance: when the environment changes (a new disease, a hotter climate), at least some variants are likely to survive and reproduce, ensuring the species continues. So variation helps the species even when it does not help every individual.
Q 3 Distinguish between asexual and sexual reproduction (any four points).
Asexual: single parent; no gametes; offspring are clones (very similar to parent); little variation; usually fast. Examples — Amoeba (binary fission), yeast (budding), Rhizopus (spores).Sexual: two parents; gametes fuse (n + n → 2n); offspring carry genes of both parents; large variation; slower. Examples — flowering plants, fish, frog, mammals.
Q 4 Describe binary fission with reference to Amoeba.
Step 1 — The Amoeba's nucleus first divides into two by mitosis.Step 2 — The cytoplasm gradually constricts in the middle, forming a furrow that deepens.Step 3 — The cytoplasm pinches off completely, leaving two roughly equal daughter Amoebae, each with its own nucleus.The plane of division can be in any direction, and each daughter grows into a full-sized Amoeba. This is asexual reproduction by binary fission.
Q 5 Explain spore formation in Rhizopus. Why are spores especially useful for the organism?
Rhizopus grows as a network of fine threads (hyphae) on damp bread. Some hyphae stand erect and develop knob-like sporangia at their tips. Inside each sporangium, hundreds of microscopic spores are produced.When the sporangium ripens, it bursts and releases the spores into the air. A spore that lands on a moist surface germinates into a new Rhizopus colony.Each spore has a thick protective wall, allowing it to survive heat, cold and dryness for long periods — a great advantage in the unpredictable environments fungi inhabit.
Q 6 What is vegetative propagation? Give three examples and state any two advantages.
Vegetative propagation is a kind of asexual reproduction in plants in which new plants develop from non-reproductive parts (root, stem or leaf) of the parent.Examples: (i) Potato — buds (eyes) on the underground stem give rise to new plants. (ii) Bryophyllum — adventitious buds on the leaf margin grow into plantlets. (iii) Sugarcane — stem cuttings with at least one node sprout into new plants.Advantages: (a) The new plants are genetically identical to the parent, so a desirable variety can be preserved exactly. (b) Plants such as banana that do not produce viable seeds can still be multiplied. (c) Flowering and fruiting begin earlier than in seed-grown plants.
Q 7 Why are gametes haploid even though parent body cells are diploid?
If gametes were diploid (2n), fertilization would give the zygote 2n + 2n = 4n chromosomes. The next generation would have 8n, then 16n — the chromosome number would double every generation and rapidly become unmanageable.By making gametes haploid (n), nature ensures that fusion restores the diploid (2n) chromosome number in the zygote and keeps it constant from generation to generation.
Q 8 Differentiate between external and internal fertilization. Give one example each.
External fertilization takes place outside the female's body, usually in water. The female releases eggs and the male releases sperm over them. Many gametes are wasted, so very large numbers are produced. Example — frog, fish.Internal fertilization takes place inside the female's body — the male transfers sperm directly into the female. Gamete wastage is much less, so few gametes are produced; the embryo is also better protected. Example — humans, birds, reptiles.
Q 9 Draw a labelled diagram of a typical bisexual flower and write the function of each part. (Description-based answer)
The four whorls of a typical flower (e.g. hibiscus) and their functions are:Sepals (calyx): green, leaf-like; protect the developing bud and may carry out photosynthesis.Petals (corolla): brightly coloured; attract insects and other pollinators for cross-pollination.Stamens (androecium): male part; each has a filament holding up an anther, in which pollen grains carrying the male gametes are produced.Pistil (gynoecium): female part; has a sticky stigma that catches pollen, a style through which the pollen tube grows, and an ovary at the base containing one or more ovules. Each ovule has the female gamete (egg).
Q 10 What is pollination? How does it differ from fertilization in flowering plants?
Pollination is the transfer of pollen grains from the anther of a stamen to the stigma of a pistil. It is carried out by agents such as wind, water and animals (especially insects).Fertilization is the fusion of the male gamete (delivered by the pollen tube) with the female gamete (egg) inside the ovule, resulting in a diploid zygote.In short — pollination delivers the pollen to the right place; fertilization is the actual fusion of gametes that takes place after the pollen tube reaches the ovule.
Q 11 Compare self-pollination and cross-pollination. Mention one advantage of cross-pollination.
Self-pollination — pollen lands on the stigma of the same flower (or another flower of the same plant). Offspring are very similar to the parent. Example — pea, wheat.Cross-pollination — pollen is transferred to a stigma of a flower on a different plant of the same species. Offspring carry mixed features of two parents. Example — mustard, papaya, maize.Advantage of cross-pollination: it produces greater genetic variation, making the population better able to survive new diseases or changes in the environment, and often gives healthier, more vigorous offspring.
Q 12 After fertilization, what changes occur in the different parts of the flower?
The zygote divides repeatedly and develops into the embryo.The ovule matures into the seed, which contains the embryo, stored food, and a protective seed coat.The ovary grows and ripens into the fruit, surrounding and protecting the seed(s) and helping in their dispersal.The other floral parts — sepals, petals, stamens and the style — usually wither and fall off as the fruit develops.
Q 13 Briefly describe how reproduction takes place in (a) a frog and (b) a mammal.
(a) Frog: Reproduction is sexual, with external fertilization. The female releases thousands of eggs into pond water, and the male releases sperm over them. Fusion takes place in water, forming zygotes that develop into tadpoles. Tadpoles grow gills, then legs, lose the tail, and metamorphose into adult frogs.(b) Mammal: Reproduction is sexual, with internal fertilization. Sperm produced in the male's testes are transferred into the female's reproductive tract, where one sperm fuses with the egg released by the ovary. The diploid zygote implants in the uterus and grows into an embryo, nourished through the placenta until birth. The young are then nursed on mother's milk.
Q 14 "Sexual reproduction is the basis of evolution." Justify this statement.
Sexual reproduction generates large amounts of variation in three ways: (i) it brings together genes of two different parents, (ii) it shuffles chromosomes randomly during gamete formation, and (iii) small DNA copying errors add new variants.When the environment changes, individuals with useful variations are more likely to survive and reproduce, so those features become more common in successive generations. This slow filtering — natural selection — gradually changes the species and may even produce new species.Without the variation supplied by sexual reproduction, natural selection would have very little to work on, and evolution would be far slower. Hence sexual reproduction is the very basis of evolution.
Q 15 A potato tuber kept in a corner of the kitchen for two weeks develops several green shoots from its eyes. Explain the biological process at work and identify it.
The "eyes" of a potato are tiny axillary buds on the surface of the underground stem (tuber).When the tuber is left in moist, warm conditions, each bud awakens, the cells inside divide, and a green shoot emerges. If planted in soil, this shoot, together with new roots, would grow into a complete potato plant — genetically identical to the parent.This is an example of vegetative propagation — a form of asexual reproduction in which new plants arise from non-reproductive parts (here, the underground stem) of the parent.
Frequently Asked Questions — NCERT Exercises & Intext Questions
How do I solve NCERT Class 9 Science Chapter 11 (Reproduction: How Life Continues) exercise questions for the CBSE board exam?
Solve NCERT Chapter 11 — Reproduction: How Life Continues — exercise questions by first reading the question carefully, writing down the given data, recalling the relevant concepts like asexual reproduction, sexual reproduction, human reproduction, and applying them step by step. This Part 4 covers every intext and end-of-chapter exercise from the NCERT textbook. Write balanced equations, label diagrams clearly and show each step — CBSE Class 9 examiners award step marks even if the final answer has a small slip. Practising these solutions strengthens conceptual clarity and builds speed for both the school exam and the upcoming Class 10 board exam.
Are the NCERT intext questions from Reproduction: How Life Continues important for the Class 9 Science exam?
Yes, NCERT intext questions for Chapter 11 Reproduction: How Life Continues are highly important for the CBSE Class 9 Science exam. Many questions in school and competitive papers are directly lifted or only slightly modified from these intext questions, and they test the foundational concepts — asexual reproduction, sexual reproduction, human reproduction — that chapter-end questions and the Class 10 board build on. Attempt every intext question first, then move on to the exercises. This practice ensures complete NCERT coverage, which is the CBSE syllabus's primary source.
What types of questions from Reproduction: How Life Continues are asked in the Class 9 Science exam?
The Class 9 Science paper (CBSE pattern) asks a mix of question types from Reproduction: How Life Continues: 1-mark MCQ and assertion-reason, 2-mark short answers, 3-mark explanations, 5-mark long answers with diagrams or derivations, and 4-mark competency-based / case-study questions. These test understanding of asexual reproduction, sexual reproduction, human reproduction, flower. Practising every NCERT exercise and intext question prepares you to answer all of these formats with confidence.
How many marks does Chapter 11 — Reproduction: How Life Continues — typically carry in the Class 9 Science paper?
Chapter 11 — Reproduction: How Life Continues — is part of the CBSE Class 9 Science syllabus and typically contributes 5–9 marks in the annual paper, depending on the year's weightage. Questions are drawn from definitions, reasoning, numerical/descriptive problems and diagrams on topics like asexual reproduction, sexual reproduction, human reproduction. Solving the NCERT exercises in this part is essential because CBSE directly references the NCERT Exploration textbook for question design.
Where can I find step-by-step NCERT solutions for Chapter 11 Reproduction: How Life Continues Class 9 Science?
You can find complete, step-by-step NCERT solutions for Chapter 11 Reproduction: How Life Continues Class 9 Science on MyAiSchool. Every intext and end-of-chapter exercise question is solved with full working, labelled diagrams and CBSE-aligned mark distribution. Solutions highlight key points about asexual reproduction, sexual reproduction, human reproduction that examiners look for. This makes revision quick and exam-focused for Class 9 CBSE students.
What is the best way to revise Reproduction: How Life Continues for the Class 9 Science exam?
The best way to revise Reproduction: How Life Continues for the CBSE Class 9 Science exam is a three-pass approach. First pass: skim the chapter and note down key terms like asexual reproduction, sexual reproduction, human reproduction in a one-page mind map. Second pass: solve every NCERT intext and exercise question without looking at the solution, then self-check. Third pass: attempt sample papers and competency-based questions under timed conditions. This structured revision secures full marks for this chapter.
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