Exercise — How do Organisms Reproduce?

11 questions✓ Free · step-by-step

11 markNCERT Cl-10 Science, Exercise Q1
Asexual reproduction takes place through budding in (a) Amoeba. (b) Yeast. (c) Plasmodium. (d) Leishmania.
Hint. Match each organism to its own specific mode of asexual reproduction from this chapter.
Step 1 — Recall each organism's mode. Amoeba and Leishmania reproduce by binary fission; Plasmodium reproduces by multiple fission.

Step 2 — Identify the budding organism. Yeast is the one that reproduces by budding, since it puts out small buds that separate and grow further.

✦ Answer: (b) Yeast.
Where students slip. Picking Amoeba — Amoeba reproduces by binary fission, splitting into two equal halves, not by budding.
21 markNCERT Cl-10 Science, Exercise Q2
Which of the following is not a part of the female reproductive system in human beings? (a) Ovary (b) Uterus (c) Vas deferens (d) Fallopian tube
Hint. One of these four structures belongs to the male reproductive system instead.
Step 1 — Classify each structure. Ovary, uterus and fallopian tube are all part of the female reproductive system.

Step 2 — Identify the odd one out. The vas deferens is the tube that carries sperm from the testes, since it belongs to the male reproductive system, not the female one.

✦ Answer: (c) Vas deferens.
Where students slip. Confusing vas deferens with fallopian tube because both are 'tubes' in a reproductive system — they belong to different sexes entirely.
31 markNCERT Cl-10 Science, Exercise Q3
The anther contains (a) sepals. (b) ovules. (c) pistil. (d) pollen grains.
Hint. The anther is part of the stamen — the flower's male reproductive part.
Step 1 — Recall what the anther is. The anther is part of the stamen, the male reproductive part of the flower.

Step 2 — Recall what it produces. The stamen produces pollen grains, since that's the yellowish powder it's specifically built to make.

✦ Answer: (d) pollen grains.
Where students slip. Picking ovules — ovules are inside the ovary, part of the pistil (the female reproductive part), not the anther.
43 marksNCERT Cl-10 Science, Exercise Q4
What are the advantages of sexual reproduction over asexual reproduction?
Hint. Think about where new combinations of variation come from, and why combining two individuals' variations speeds this up.
Step 1 — Recall the source of variation in general. DNA copying always introduces some variation, but on its own this makes variation accumulate only slowly.

Step 2 — Explain what sexual reproduction adds. Sexual reproduction combines the already-varied DNA of two different individuals, creating new combinations of variants much faster than asexual reproduction (which just passes on one individual's variations) could.

Step 3 — State the resulting advantage. Since each combination is novel, sexual reproduction generates far greater variation in a population, which is more useful for that population's long-term survival if the environment changes.

✦ Answer: Sexual reproduction combines variations from two individuals into new combinations, generating far more variation, far faster, than asexual reproduction alone — better equipping the population to survive future environmental change.
Where students slip. Saying sexual reproduction is 'more reliable' or 'produces healthier offspring' — the actual, chapter-based advantage is specifically about generating variation faster by combining two individuals' DNA, not about offspring quality.
52 marksNCERT Cl-10 Science, Exercise Q5
What are the functions performed by the testis in human beings?
Hint. The testis does two separate jobs — one about producing cells, one about producing a chemical messenger.
Step 1 — First function. The testes produce the male germ-cells, sperm.

Step 2 — Second function. The testes also secrete the hormone testosterone, since it's this hormone that regulates sperm formation and brings about the bodily changes seen in boys at puberty.

✦ Answer: The testes produce sperm and secrete testosterone, which regulates sperm formation and drives puberty changes in boys.
Where students slip. Naming only sperm production — the testes are also an endocrine gland, secreting testosterone, which is a distinct and equally important function.
62 marksNCERT Cl-10 Science, Exercise Q6
Why does menstruation occur?
Hint. Think about what the uterus lining was preparing for every month, and what happens to that preparation when it isn't needed.
Step 1 — Recall the monthly preparation. Every month, the uterus lining becomes thick and spongy, preparing to nourish an embryo in case fertilisation occurs.

Step 2 — Explain what happens if there's no fertilisation. If the released egg is not fertilised, this thickened lining is no longer needed.

Step 3 — State the outcome. The lining slowly breaks down and is shed through the vagina as blood and mucus — this is menstruation, occurring roughly every month.

✦ Answer: Menstruation occurs because the uterus lining, built up each month to nourish a potential embryo, is shed when the egg released that month isn't fertilised.
Where students slip. Describing menstruation as the body 'getting rid of the egg' — the egg itself survives only about a day if unfertilised; menstruation is specifically the shedding of the built-up uterine lining, not the egg.
72 marksNCERT Cl-10 Science, Exercise Q7
Draw a labelled diagram of the longitudinal section of a flower.
Hint. Work outward from the centre: ovary, then the male and female parts around it, then the outer whorls.
Step 1 — Female part (pistil), from the centre outward. Ovary (swollen bottom part, containing ovules) → style (elongated middle part) → stigma (sticky terminal part).

Step 2 — Male part (stamen). Filament topped by the anther, since this is the part that produces pollen grains.

Step 3 — Outer whorls. Petals (colourful, surrounding the reproductive parts) and sepals (green, outermost, protecting the bud).

✦ Answer: A correctly labelled diagram shows, from the centre out: ovary–style–stigma (pistil) and filament–anther (stamen), surrounded by petals, surrounded by sepals.
Where students slip. Placing the ovary at the top of the diagram instead of the base — the pistil's swollen ovary is the bottom part, with the style and stigma extending upward from it.
82 marksNCERT Cl-10 Science, Exercise Q8
What are the different methods of contraception?
Hint. Group them by how each one works — a physical block, a hormonal change, a device in the uterus, or a surgical block.
Step 1 — Barrier methods. Condoms or similar coverings create a mechanical barrier so sperm cannot reach the egg.

Step 2 — Hormonal methods. Oral contraceptive pills change the body's hormonal balance so eggs are not released.

Step 3 — Intrauterine devices. Devices such as the loop or copper-T are placed in the uterus to prevent pregnancy.

Step 4 — Surgical methods. Blocking the vas deferens (in males) or the fallopian tube (in females) prevents sperm or egg from reaching the site of fertilisation.

✦ Answer: Barrier methods (condoms), hormonal methods (oral pills), intrauterine devices (loop, copper-T), and surgical methods (blocking the vas deferens or fallopian tube).
Where students slip. Listing only barrier and hormonal methods — surgical and intrauterine methods are equally valid categories covered in this chapter.
92 marksNCERT Cl-10 Science, Exercise Q9
How are the modes for reproduction different in unicellular and multicellular organisms?
Hint. A single cell can simply become two — but a body organised into tissues and organs can't divide the same way.
Step 1 — Unicellular organisms. A single cell can reproduce by dividing itself directly — as in binary fission or multiple fission — since the whole organism is just that one cell.

Step 2 — Multicellular organisms. Their cells are organised into tissues, and tissues into organs placed at fixed positions, so the whole body cannot simply divide cell-by-cell; instead, only a specific cell type (capable of proliferating and producing other cell types) drives reproduction.

✦ Answer: Unicellular organisms reproduce by directly dividing the single cell (fission). Multicellular organisms, being organised into tissues and organs, rely instead on specific reproductive cell types capable of growing and producing all the other cell types needed.
Where students slip. Assuming multicellular organisms could just 'split like a unicellular one' if they wanted to — their organised tissue/organ structure specifically rules this out, which is why they need a dedicated reproductive cell type instead.
102 marksNCERT Cl-10 Science, Exercise Q10
How does reproduction help in providing stability to populations of species?
Hint. Think about what reproduction is actually preserving generation after generation, and why that matters for a population's niche.
Step 1 — Recall what reproduction preserves. DNA copying during reproduction maintains the body-design features that let an organism use its particular ecological niche.

Step 2 — Explain how this stabilises a population. As long as this copying stays consistent across generations, the population continues to be well-suited to its niche, keeping its numbers stable over time.

Step 3 — Note the built-in safeguard. Since some variation is still generated in the process, a population isn't left completely vulnerable if its niche changes — some individuals may survive due to those variations.

✦ Answer: Reproduction maintains the body-design features (via DNA copying) that keep a population suited to its niche, stabilising its numbers, while the small variations generated along the way also give the population a chance to survive if that niche changes.
Where students slip. Focusing only on variation's role and forgetting reproduction's basic stabilising function — consistent DNA copying is what maintains a population's fit to its niche in the first place; variation is a secondary safeguard on top of that.
112 marksNCERT Cl-10 Science, Exercise Q11
What could be the reasons for adopting contraceptive methods?
Hint. Think beyond pregnancy prevention alone — what else does the chapter connect contraception to at a societal level?
Step 1 — Health reason. Pregnancy makes major demands on a woman's body and mind, so avoiding pregnancy when she isn't ready protects her health.

Step 2 — Personal/social reason. Couples may wish to control the timing or number of children for personal, family, or social reasons.

Step 3 — Societal reason. Contraception also helps avoid the misuse of pregnancy-related choices, such as illegal sex-selective practices, and supports maintaining a healthy population sex ratio.

✦ Answer: To protect a woman's health from an unwanted or ill-timed pregnancy, to allow couples to choose the timing/number of children, and to support broader social goals like population control and preventing misuse such as sex-selective practices.
Where students slip. Reducing the answer to just 'to avoid having a baby' — the chapter frames this around health protection and social/population-level reasons, not just personal preference.

Solutions written by the tuition.in editorial team and checked against the NCERT Class 10 Science textbook, Reprint 2026-27 (jesc107.pdf) — three in-text question sets (12 questions total) plus one end-of-chapter Exercise (11 questions, not 17 as some older manifests claim). Unchanged by rationalisation.. Questions are referenced from the NCERT textbook for identification.

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