This MCQ module is based on: How Do Organisms Reproduce? – NCERT Exercises
TOPIC 28 OF 50
How Do Organisms Reproduce? – NCERT Exercises
🎓 Class 10
Science
CBSE
Theory
Ch 7 — How do Organisms Reproduce?
⏱ ~17 min
🌐 Language: [gtranslate]
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Chapter Summary — How do Organisms Reproduce?
Reproduction is the life process by which organisms produce new individuals of their own kind, ensuring the continuity of the species and the transfer of genetic information (with small variations that fuel evolution).
Asexual reproduction
Single parent; offspring nearly identical. Modes: fission (Amoeba, Plasmodium), fragmentation (Spirogyra), regeneration (Planaria, Hydra), budding (Hydra, yeast), vegetative propagation (potato, Bryophyllum, grafting) and spore formation (Rhizopus).
Sexual reproduction in plants
Flower is the organ. Stamens produce pollen (male), pistil (stigma, style, ovary) bears ovules (female). Pollination → pollen tube → fertilisation → zygote. Ovule → seed; ovary → fruit.
Reproduction in humans
Male: testes (sperm + testosterone), scrotum, epididymis, vas deferens, seminal vesicles, prostate, urethra. Female: ovaries (egg + oestrogen/progesterone), fallopian tube, uterus, vagina. Fertilisation occurs in the fallopian tube; foetus develops in the uterus.
Menstrual cycle
About 28 days. Ovulation ~day 14. If egg unfertilised, thick uterine lining sheds as menstruation. Completely natural and healthy.
Placenta & pregnancy
Embryo implants in uterus; placenta exchanges nutrients, oxygen and wastes with mother via the umbilical cord. Gestation ~9 months.
Reproductive health
STDs (gonorrhoea, syphilis, AIDS). Contraception: barrier, hormonal, IUD, surgical. Prenatal sex determination is illegal in India (PCPNDT Act) to protect the girl child.
Keyword Grid
DNA copyingDuplication of genetic material during cell division.
VariationSmall differences arising from imperfect DNA copying.
Binary fissionSplitting into two equal daughters (Amoeba).
Multiple fissionMany daughters at once inside a cyst (Plasmodium).
BuddingNew individual grows as an outgrowth (Hydra, yeast).
RegenerationWhole new body from a cut piece (Planaria).
Vegetative propagationNew plant from root, stem or leaf.
SporangiumSpore-containing knob in Rhizopus.
GameteReproductive cell (sperm / egg).
PollinationPollen transfer to stigma.
FertilisationFusion of male and female gametes.
ZygoteCell produced by fertilisation.
OvulationRelease of a mature egg from the ovary.
MenstruationShedding of uterine lining if egg is unfertilised.
PlacentaOrgan connecting foetus to mother's blood supply.
ContraceptionVoluntary prevention of pregnancy.
NCERT Exercises — Full Solutions
Click "Show Solution" below each question to reveal the answer.
Q1 Asexual reproduction takes place through budding in:
(a) Amoeba (b) Yeast (c) Plasmodium (d) Leishmania
(a) Amoeba (b) Yeast (c) Plasmodium (d) Leishmania
Answer: (b) Yeast. A small bud forms on the parent cell, grows and eventually separates as a new individual. Amoeba and Leishmania reproduce by binary fission; Plasmodium by multiple fission.
Q2 What is the importance of DNA copying in reproduction?
Answer: DNA carries the complete "body plan" of an organism. Accurate copying ensures that offspring inherit the parent's traits, which is why the species continues to look and function the same from generation to generation. At the same time, tiny copying errors produce variations. These variations give populations the flexibility to adapt to changing environments — the raw material of evolution. So DNA copying achieves both continuity (like parent) and change (slight variations).
Q3 Why is variation beneficial to the species but not necessarily for the individual?
Answer: An individual organism has a fixed environment. Any variation that does not suit that environment may actually harm or kill that individual. But a species lives through long time scales during which the environment changes. When it does (rising temperature, new disease, loss of food), the few individuals who happened to carry a "useful" variation survive and pass it on. Over time the population adapts. So variation is often neutral or harmful to the single organism but is vital insurance for the species.
Q4 How does binary fission differ from multiple fission?
Answer: In binary fission the parent cell divides into two equal daughter cells by a single division of the nucleus followed by the cytoplasm. Example: Amoeba, Leishmania, bacteria.
In multiple fission the parent first forms a protective cyst; inside the cyst the nucleus divides many times (producing many nuclei), and finally the cytoplasm splits around each nucleus to release many daughter cells at once. Example: Plasmodium. Multiple fission is typically an emergency response to unfavourable conditions.
In multiple fission the parent first forms a protective cyst; inside the cyst the nucleus divides many times (producing many nuclei), and finally the cytoplasm splits around each nucleus to release many daughter cells at once. Example: Plasmodium. Multiple fission is typically an emergency response to unfavourable conditions.
Q5 How will an organism benefit if it reproduces through spores?
Answer: Spores are very small and extremely light, produced in thousands inside a sporangium. They are dispersed easily by wind and water, so the organism can colonise far-away places. Spores are surrounded by a tough protective coat and can survive unfavourable conditions (dryness, temperature extremes) for long periods. When moisture and warmth return, each spore can germinate into a new individual — giving the organism a huge reproductive success rate.
Q6 Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Answer: Complex organisms like mammals have highly specialised organ systems — heart, brain, lungs, kidneys — each developed from specific embryonic cells. Their adult cells are committed to one role and cannot switch into any other cell type. A fragment of such an organism would be missing most organs and could not replace them. Regeneration is therefore possible only in simple-bodied animals like Planaria and Hydra, which still possess many unspecialised cells capable of dividing and turning into any tissue.
Q7 Why is vegetative propagation practised for growing some types of plants?
Answer: Several reasons — (i) the new plants are genetic copies of the parent, so desirable traits (sweet fruit, fragrant flower) are guaranteed; (ii) the plants begin to flower and fruit faster than those grown from seed; (iii) plants that cannot produce viable seeds (banana, seedless grape, orange, rose) can still be multiplied this way; (iv) the method is cheap and simple and requires only a piece of root, stem or leaf.
Q8 What is the importance of DNA copying in reproduction?
Answer: (Same idea as Q2, in brief.) Accurate DNA copying transfers the parent's genetic information to the offspring, ensuring the child organism resembles its parent and the species continues across generations. Minor inaccuracies during copying introduce small variations, which accumulate over generations and allow the species to evolve and adapt to environmental changes.
Q9 How is the process of pollination different from fertilisation?
Answer:
Pollination — the transfer of pollen grains from an anther to a stigma. It is an external event, carried out by agents like insects, wind or water. No fusion of gametes is involved.
Fertilisation — the internal fusion of the male gamete (carried down by the pollen tube) with the female gamete (egg) inside the ovule, forming the zygote.
Pollination is a prerequisite; fertilisation follows only if pollination is successful.
Pollination — the transfer of pollen grains from an anther to a stigma. It is an external event, carried out by agents like insects, wind or water. No fusion of gametes is involved.
Fertilisation — the internal fusion of the male gamete (carried down by the pollen tube) with the female gamete (egg) inside the ovule, forming the zygote.
Pollination is a prerequisite; fertilisation follows only if pollination is successful.
Q10 What is the role of the seminal vesicles and the prostate gland?
Answer: The seminal vesicles and the prostate gland secrete fluids that are added to the sperms as they pass through the vas deferens. The combined sperm + fluid mixture is called semen. These fluids (i) provide nutrition (such as fructose) for the sperms, (ii) maintain a suitable pH, and (iii) give the sperms a liquid medium in which they can swim efficiently towards the egg.
Q11 What are the changes seen in girls at the time of puberty?
Answer: The changes are driven by the hormone oestrogen. They include — growth of breasts; widening of the hips; appearance of hair in the under-arm and pubic regions; onset of menstruation (periods); occasional acne and oily skin; a general growth spurt; and emotional changes. All these changes are natural and mark the transition into adulthood.
Q12 How does the embryo get nourishment inside the mother's body?
Answer: After implantation, a special disc-shaped organ called the placenta develops inside the mother's uterine wall. The placenta is connected to the embryo through the umbilical cord. On the embryo's side it has thousands of finger-like projections (villi) that provide a very large surface area. The mother's blood flowing past these villi delivers glucose, amino acids, oxygen and other nutrients into the embryo's blood (through a thin membrane), and takes away the embryo's waste products like carbon dioxide and urea. The two blood streams never mix directly — exchange is by diffusion.
Q13 If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?
Answer: No. The Copper-T is an intra-uterine device (IUD). It prevents pregnancy by stopping the implantation of a fertilised embryo in the uterine wall. It does not form any barrier between sexual partners, so it gives no protection against sexually transmitted diseases like gonorrhoea, syphilis or AIDS. To be protected against STDs, a barrier method such as a condom must be used.
Frequently Asked Questions — NCERT Exercises & Intext Questions
How do I solve NCERT Class 10 Science Chapter 7 (How Do Organisms Reproduce?) exercise questions for the CBSE board exam?
Solve NCERT Chapter 7 — How Do Organisms Reproduce? — exercise questions by first reading the question carefully, writing down the given data, recalling the relevant concepts like reproduction, asexual, sexual, 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 10 board examiners award step marks even if the final answer has a small slip. Practising these solutions strengthens conceptual clarity and builds speed for the board exam.
Are the NCERT intext questions from How Do Organisms Reproduce? important for the Class 10 board exam?
Yes, NCERT intext questions for Chapter 7 How Do Organisms Reproduce? are highly important for the CBSE Class 10 Science board exam. Many board questions are directly lifted or only slightly modified from these intext questions, and they test the foundational concepts — reproduction, asexual, sexual — that chapter-end questions build on. Attempt every intext question first, then move on to the exercises. This practice ensures complete NCERT coverage, which is the CBSE exam's primary source.
What types of questions from How Do Organisms Reproduce? are asked in the CBSE Class 10 Science board exam?
The CBSE Class 10 board paper asks a mix of question types from How Do Organisms Reproduce?: 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 reproduction, asexual, sexual, flower. Practising every NCERT exercise and intext question prepares you to answer all of these formats with confidence.
How many marks does Chapter 7 — How Do Organisms Reproduce? — carry in the Class 10 Science CBSE paper?
Chapter 7 — How Do Organisms Reproduce? — is part of the Class 10 Science syllabus and typically contributes 5–9 marks in the CBSE board paper, depending on the annual weightage. Questions are drawn from definitions, reasoning, numerical/descriptive problems and diagrams on topics like reproduction, asexual, sexual. Solving the NCERT exercises in this part is essential because CBSE directly references NCERT for question design.
Where can I find step-by-step NCERT solutions for Chapter 7 How Do Organisms Reproduce? Class 10 Science?
You can find complete, step-by-step NCERT solutions for Chapter 7 How Do Organisms Reproduce? Class 10 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 reproduction, asexual, sexual that examiners look for. This makes revision quick and exam-focused for Class 10 CBSE board students.
What is the best way to revise How Do Organisms Reproduce? before the Class 10 Science board exam?
The best way to revise How Do Organisms Reproduce? for the CBSE Class 10 Science board exam is a three-pass approach. First pass: skim the chapter and note down key terms like reproduction, asexual, sexual 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 previous CBSE board questions and competency-based questions under timed conditions. This structured revision secures full marks for this chapter.
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