Assertion (A): Vegetative propagation is considered a form of asexual reproduction. Reason (R): Offspring from vegetative propagation are genetically identical to the parent plant.

Both A and R are true but R is not the correct explanation of A.

Both A and R are true and R is the correct explanation of A.

Both A and R are true but R is not the correct explanation of A.

How does the structure of a bisexual flower prevent self-pollination? Explain any two mechanisms.

Two mechanisms that prevent self-pollination in bisexual flowers are: (1) Protandry – the anthers mature and release pollen before the stigma becomes receptive; (2) Self-incompatibility – the pollen from the same flower cannot fertilize the ovule due to genetic barriers.

A farmer wants to grow a whole field of sugarcane quickly using a few stalks. Which method of reproduction would you suggest and why?

I would suggest vegetative propagation through stem cuttings. Sugarcane is propagated by planting sections of the stem having nodes, which develop roots and shoots, producing new plants rapidly that are genetically identical to the parent.

In human reproduction, the fusion of sperm and egg results in a zygote that is genetically unique. Explain how the process of meiosis contributes to this genetic variation, even though both parents contribute equal genetic material. Why is the zygote not a clone of either parent?

Meiosis reduces the chromosome number to half (haploid) in gametes. During meiosis, crossing-over between homologous chromosomes exchanges genetic material, creating new combinations of alleles. Independent assortment of chromosomes also leads to a mix of paternal and maternal chromosomes in each gamete. When haploid sperm and egg fuse, the zygote regains the diploid number, with a combination of chromosomes from both parents. Since each parent contributes a unique set of recombined chromosomes, the zygote is genetically distinct from both parents and is not a clone. Genetic variation arises due to recombination and random fertilization.

Describe the hormonal control of the menstrual cycle in human females. Explain what happens to the uterine lining if fertilization does not take place.

The menstrual cycle is regulated by hormones from the pituitary and ovaries. The pituitary releases FSH and LH. FSH stimulates growth of ovarian follicles, which secrete estrogen. Estrogen causes thickening of the uterine lining. A surge in LH triggers ovulation. After ovulation, the ruptured follicle forms the corpus luteum, which secretes progesterone. Progesterone maintains the uterine lining. If fertilization does not occur, the corpus luteum degenerates, progesterone levels drop, and the thickened uterine lining breaks down and is shed during menstruation.

a) Draw a labelled diagram depicting the stages of binary fission in Amoeba. b) Explain the process of budding in Hydra with the help of a labelled diagram. State one key difference between the two processes.

Binary fission in Amoeba: The parent cell divides into two daughter cells by mitosis. Initially, the nucleus divides, followed by the division of the cytoplasm. Budding in Hydra: A small outgrowth called bud develops on the body of the parent. The bud grows, develops tentacles, and eventually detaches to live independently. Key difference: Binary fission results in two equal-sized offspring, while budding produces a smaller bud that separates from the parent.

Describe the process of fertilization in flowering plants. Explain the post-fertilization changes that lead to the formation of seed and fruit. Draw a labelled diagram of a typical embryo sac.

Fertilization: Pollen grain germinates on stigma, pollen tube grows through style, carrying two male gametes. One male gamete fuses with egg cell (syngamy) to form zygote. The other fuses with secondary nucleus (triple fusion) forming primary endosperm nucleus. This double fertilization is unique to angiosperms. After fertilization: Zygote develops into embryo; ovule becomes seed; ovary becomes fruit; integuments form seed coat; endosperm provides nutrition.

A 15-year-old girl experiences menarche and starts having regular menstrual cycles. She notices changes in her body and mood during different phases of the cycle. Her mother advises her on maintaining hygiene and explains that hormones control these changes. The girl learns that ovulation typically occurs around the 14th day of a 28-day cycle. (1) Explain the role of hormones in regulating the menstrual cycle. (2) Mention two important measures for menstrual hygiene. (3) If her cycle is 28 days, on which days is she most likely to conceive? Explain briefly.

1. Hormones orchestrate the cycle: FSH and LH from pituitary, estrogen and progesterone from ovaries, regulating follicle development, ovulation, and uterine lining. 2. Use sanitary pads, maintain cleanliness. 3. Fertile window: days 12-16, peaking at ovulation (day 14).

Class 10 Science Chapter 7: How do Organisms Reproduce? — Important Questions & Sample Paper

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Yes — this page has 44+ original Class 10 Science Chapter 7 (“How do Organisms Reproduce?”) important questions with answers (Multiple Choice (MCQ), Assertion–Reason, Short Answer, Short Answer, Long Answer, Case Study). Practise them free, or generate a full CBSE board-pattern sample paper (80 marks) and export it to PDF or Word — in English & Hindi, for 2026-27.

Chapter 7: How do Organisms Reproduce? in CBSE Class 10 Science introduces students to the essential biological process of reproduction. The chapter distinguishes between asexual reproduction—where offspring are genetically identical to a single parent, seen in methods like binary fission (Amoeba), budding (Hydra), fragmentation (Spirogyra), regeneration (Planaria), and vegetative propagation (sugarcane, rose)—and sexual reproduction, which involves fusion of gametes, promoting genetic diversity. In flowering plants, the focus is on the structure of a bisexual flower, pollination agents and mechanisms (self vs. cross), double fertilization, and post-fertilization development of embryo, seed, and fruit. The human reproductive system is studied with labelled diagrams of male and female organs, gamete formation, and the journey from fertilization to implantation. The chapter emphasizes the importance of variation for evolution and also touches upon reproductive health. Exam questions frequently ask students to distinguish between modes of reproduction, explain the role of meiosis in genetic uniqueness, justify vegetative propagation for agriculture, draw and label reproductive structures, and describe fertilisation and post-fertilisation changes. Our question bank provides targeted practice covering all these critical areas, helping teachers assess conceptual clarity and application skills.

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Science — How do Organisms Reproduce?

Class 10Time: 3 hrsMax Marks: 80

SECTION A

1.
Which part of the flower develops into the fruit?
(a) Stamen(b) Petal(c) Ovary(d) Sepal
1
2.
The process of a new organism developing from an outgrowth on the parent body is called:
(a) Regeneration(b) Fission(c) Budding(d) Fragmentation
1
3.
In human females, fertilization normally takes place in the:
(a) Ovary(b) Uterus(c) Fallopian tube(d) Vagina
1

+ 41 more questions in the full paper

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In a CBSE exam, this chapter typically contributes questions across the following types. The last column shows how many original questions of each type we have ready in our bank for this chapter:

Question type	Marks each	In our bank
Multiple Choice (MCQ)	1 mark	13
Assertion–Reason	1 mark	6
Short Answer	2 marks	8
Short Answer	3 marks	6
Long Answer	5 marks	5
Case Study	4 marks	6

44 original, exam-style questions in our bank for this chapter — with answers.

Important & sample questions (with answers)

Real, exam-style questions to practise and revise — each with its answer. Generate a full paper for unlimited more.

Q1. Which part of the flower develops into the fruit?
1 mark
Multiple Choice (MCQ)
(A) Stamen(B) Petal(C) Ovary(D) Sepal
▸ Answer▾ Answer
c) Ovary
Q2. The process of a new organism developing from an outgrowth on the parent body is called:
1 mark
Multiple Choice (MCQ)
(A) Regeneration(B) Fission(C) Budding(D) Fragmentation
▸ Answer▾ Answer
c) Budding
Q3. In human females, fertilization normally takes place in the:
1 mark
Multiple Choice (MCQ)
(A) Ovary(B) Uterus(C) Fallopian tube(D) Vagina
▸ Answer▾ Answer
c) Fallopian tube
Q4. A piece of a carrot is cut off and planted in moist soil. It eventually grows into a full plant. This is an example of:
1 mark
Multiple Choice (MCQ)
(A) Cutting(B) Grafting(C) Layering(D) Tissue culture
▸ Answer▾ Answer
a) Cutting
Q5. Assertion (A): Vegetative propagation is considered a form of asexual reproduction. Reason (R): Offspring from vegetative propagation are genetically identical to the parent plant.
1 mark
Assertion–Reason
(A) Both A and R are true and R is the correct explanation of A.(B) Both A and R are true but R is not the correct explanation of A.(C) A is true but R is false.(D) A is false but R is true.
▸ Answer▾ Answer
Both A and R are true but R is not the correct explanation of A.
Q6. How does the structure of a bisexual flower prevent self-pollination? Explain any two mechanisms.
2 marks
Short Answer
▸ Answer▾ Answer
Two mechanisms that prevent self-pollination in bisexual flowers are: (1) Protandry – the anthers mature and release pollen before the stigma becomes receptive; (2) Self-incompatibility – the pollen from the same flower cannot fertilize the ovule due to genetic barriers.
Q7. A farmer wants to grow a whole field of sugarcane quickly using a few stalks. Which method of reproduction would you suggest and why?
2 marks
Short Answer
▸ Answer▾ Answer
I would suggest vegetative propagation through stem cuttings. Sugarcane is propagated by planting sections of the stem having nodes, which develop roots and shoots, producing new plants rapidly that are genetically identical to the parent.
Q8. In human reproduction, the fusion of sperm and egg results in a zygote that is genetically unique. Explain how the process of meiosis contributes to this genetic variation, even though both parents contribute equal genetic material. Why is the zygote not a clone of either parent?
3 marks
Short Answer
▸ Answer▾ Answer
Meiosis reduces the chromosome number to half (haploid) in gametes. During meiosis, crossing-over between homologous chromosomes exchanges genetic material, creating new combinations of alleles. Independent assortment of chromosomes also leads to a mix of paternal and maternal chromosomes in each gamete. When haploid sperm and egg fuse, the zygote regains the diploid number, with a combination of chromosomes from both parents. Since each parent contributes a unique set of recombined chromosomes, the zygote is genetically distinct from both parents and is not a clone. Genetic variation arises due to recombination and random fertilization.
Q9. Describe the hormonal control of the menstrual cycle in human females. Explain what happens to the uterine lining if fertilization does not take place.
3 marks
Short Answer
▸ Answer▾ Answer
The menstrual cycle is regulated by hormones from the pituitary and ovaries. The pituitary releases FSH and LH. FSH stimulates growth of ovarian follicles, which secrete estrogen. Estrogen causes thickening of the uterine lining. A surge in LH triggers ovulation. After ovulation, the ruptured follicle forms the corpus luteum, which secretes progesterone. Progesterone maintains the uterine lining. If fertilization does not occur, the corpus luteum degenerates, progesterone levels drop, and the thickened uterine lining breaks down and is shed during menstruation.
Q10. a) Draw a labelled diagram depicting the stages of binary fission in Amoeba. b) Explain the process of budding in Hydra with the help of a labelled diagram. State one key difference between the two processes.
5 marks
Long Answer
▸ Answer▾ Answer
Binary fission in Amoeba: The parent cell divides into two daughter cells by mitosis. Initially, the nucleus divides, followed by the division of the cytoplasm. Budding in Hydra: A small outgrowth called bud develops on the body of the parent. The bud grows, develops tentacles, and eventually detaches to live independently. Key difference: Binary fission results in two equal-sized offspring, while budding produces a smaller bud that separates from the parent.
Q11. Describe the process of fertilization in flowering plants. Explain the post-fertilization changes that lead to the formation of seed and fruit. Draw a labelled diagram of a typical embryo sac.
5 marks
Long Answer
▸ Answer▾ Answer
Fertilization: Pollen grain germinates on stigma, pollen tube grows through style, carrying two male gametes. One male gamete fuses with egg cell (syngamy) to form zygote. The other fuses with secondary nucleus (triple fusion) forming primary endosperm nucleus. This double fertilization is unique to angiosperms. After fertilization: Zygote develops into embryo; ovule becomes seed; ovary becomes fruit; integuments form seed coat; endosperm provides nutrition.
Q12. A 15-year-old girl experiences menarche and starts having regular menstrual cycles. She notices changes in her body and mood during different phases of the cycle. Her mother advises her on maintaining hygiene and explains that hormones control these changes. The girl learns that ovulation typically occurs around the 14th day of a 28-day cycle.
4 marks
Case Study
1. (i) Explain the role of hormones in regulating the menstrual cycle.2 marks
2. (ii) Mention two important measures for menstrual hygiene.1 mark
3. (iii) If her cycle is 28 days, on which days is she most likely to conceive? Explain briefly.1 mark
▸ Answer▾ Answer
1. Hormones orchestrate the cycle: FSH and LH from pituitary, estrogen and progesterone from ovaries, regulating follicle development, ovulation, and uterine lining. 2. Use sanitary pads, maintain cleanliness. 3. Fertile window: days 12-16, peaking at ovulation (day 14).

Frequently asked questions

How does self-pollination differ from cross-pollination in plants?

Self-pollination involves transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant, resulting in genetically similar offspring. Cross-pollination involves transfer of pollen between flowers of different plants of the same species, promoting genetic variation. Self-pollination does not require pollinating agents, while cross-pollination depends on wind, water, or animals.

Why is vegetative propagation considered a better method for cultivating plants like sugarcane and banana?

Vegetative propagation produces genetically identical plants (clones) quickly, preserving desirable traits like high yield or disease resistance. It is the only method for plants that do not produce viable seeds, such as sugarcane and banana, and allows rapid multiplication from a single parent stem cutting or rhizome.

What post-fertilization changes occur in a flower to form a fruit?

After fertilization, the zygote develops into an embryo within the ovule. The ovule becomes the seed, and the ovary enlarges and ripens into the fruit. Sepals, petals, and stamens usually wither and fall off. In some cases, the ovary wall differentiates into a fleshy or dry fruit wall.

How does meiosis contribute to genetic variation in sexually reproducing organisms?

Meiosis halves the chromosome number during gamete formation and involves crossing over and independent assortment, which shuffle parental genes. When sperm and egg fuse, the resulting zygote has a unique combination of genes from both parents, ensuring offspring are not clones.

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