This MCQ module is based on: Sexual Reproduction in Flowering Plants
TOPIC 26 OF 50
Sexual Reproduction in Flowering Plants
🎓 Class 10
Science
CBSE
Theory
Ch 7 — How do Organisms Reproduce?
⏱ ~17 min
🌐 Language: [gtranslate]
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7.3 Sexual Reproduction — Why Bother With a Partner?
Asexual reproduction is fast and efficient, but its offspring are almost exact copies of the parent. A single virus or climate change could wipe out the whole population. Sexual reproduction solves this problem. Two parents contribute DNA through specialised cells called gametes. When the male gamete fuses with the female gamete a new cell called the zygote is formed. The zygote carries a mixture of the two parents' DNA — so the offspring is never identical to either parent. This shuffling is the reason no two siblings (except identical twins) look exactly alike, and it is the foundation of biological evolution.
Key terms: Gametes — reproductive cells with half the number of chromosomes. Fertilisation — fusion of male and female gametes. Zygote — the single diploid cell formed after fertilisation, which develops into the new organism.
7.3.1 Sexual Reproduction in Flowering Plants
In flowering plants (angiosperms), the flower is the reproductive organ. A typical flower has four concentric whorls, arranged from outside to inside:
| Whorl | Parts | Function |
|---|---|---|
| Calyx | Sepals (green) | Protect the bud before it opens |
| Corolla | Petals (coloured) | Attract pollinators (insects, birds) |
| Androecium | Stamens (anther + filament) — male | Produce pollen grains |
| Gynoecium | Pistil = stigma + style + ovary — female | Receive pollen; contain ovules |
Inside each anther thousands of pollen grains are produced — the male gametes are packaged inside them. The pistil sits in the centre of the flower. Its sticky top is the stigma, connected by a tube called the style to the swollen base — the ovary. Inside the ovary are one or more ovules, each containing the female gamete (the egg).
Flowers with both stamens and pistil in the same flower are called bisexual (hibiscus, mustard). Flowers with only stamens or only pistil are called unisexual (papaya, watermelon).
Pollination — Pollen on the Move
Pollination is the transfer of pollen from an anther to a stigma. Depending on where the pollen lands:
- Self-pollination — pollen lands on the stigma of the same flower (or another flower on the same plant).
- Cross-pollination — pollen is carried to a flower of a different plant of the same species. Carriers called pollinating agents include insects (bees, butterflies), wind, water and birds.
Cross-pollination is biologically preferred because it produces more variation in the offspring.
Fertilisation — Pollen to Zygote
Once a pollen grain lands on the sticky stigma, it germinates — a pollen tube grows out of the pollen and extends down through the style. The male gamete travels inside this tube. On reaching an ovule, the pollen tube delivers the male gamete, which fuses with the female gamete (egg). This fusion is called fertilisation and the product is the zygote (2n).
Post-fertilisation Changes
After fertilisation, several coordinated changes occur in the flower:
- Zygote divides many times → becomes the embryo.
- Ovule develops a tough protective coat → becomes the seed.
- Ovary grows large and fleshy (or dry) → becomes the fruit.
- Sepals, petals, stamens, stigma and style usually wither and fall off as they are no longer needed.
Under suitable conditions the seed germinates: water absorption activates enzymes, the embryo starts to grow, a tiny root (radicle) emerges first, then a tiny shoot (plumule). The seedling draws food from the stored food reserves (endosperm / cotyledons) until it develops green leaves that can make their own food. And a new plant is born — different from both parents because of sexual reproduction.
Activity 7.2 — Dissecting a Hibiscus FlowerL3 Apply
Aim: To identify the four whorls of a flower and locate the male and female parts.
Procedure:
- Collect a fresh hibiscus flower. Separate out the parts from outside to inside using forceps.
- Arrange them in order on a sheet of paper and label: sepals, petals, stamens and pistil.
- With a razor blade cut the ovary vertically. Observe with a hand lens.
Predict: Where will you find pollen? Why is the stigma sticky? What do the tiny dots inside the ovary represent?
Observation: The outer green whorl is the calyx (sepals); next the bright pink whorl is the corolla (petals); the thread-like structures with yellow tips form the androecium (stamens) — the yellow powder on the tips is pollen; in the centre is the pistil, with a feathery red stigma and a green swollen ovary at the base. Cutting the ovary vertically shows tiny white ovules inside.
Explanation: The stigma is sticky to trap pollen. The yellow powder is thousands of pollen grains containing male gametes. Each dot inside the ovary is an ovule containing the female gamete. After fertilisation the ovules would become seeds and the ovary a fruit.
Interactive — Label the Flower
Click each part. The panel tells you its name, whorl and job.
Tap a part to see what it does.
Competency-Based Questions
Arjun plants two identical mustard plants in separate net cages. In cage A he releases honey bees; cage B is sealed. After a few weeks, cage A plants produce plump pods full of seeds, while cage B has only shrivelled pods with very few seeds.
Q1. Explain the difference in terms of pollination and fertilisation. L3 Apply
In cage A, bees transfer pollen between flowers, causing cross-pollination. Pollen tubes form, fertilisation occurs and ovules develop into seeds inside healthy fruits. In cage B there is no pollinating agent, so most flowers are not pollinated, fertilisation fails and ovules do not develop into seeds.
Q2. (MCQ) After fertilisation, the ovary develops into L1 Remember
(c) Fruit. The ovule becomes the seed and the ovary becomes the fruit.
Q3. Differentiate between pollination and fertilisation. L2 Understand
Pollination is the physical transfer of pollen from anther to stigma (an external event). Fertilisation is the internal fusion of the male gamete (delivered by the pollen tube) with the egg inside the ovule. Pollination must happen before fertilisation.
Q4. Fill in the blank — In a flower, the male reproductive part is called ______ and the female reproductive part is called ______. L1 Remember
Stamen (androecium); Pistil (gynoecium/carpel).
Q5. Why do flowers of insect-pollinated plants typically have bright petals and a sweet scent, while wind-pollinated flowers are often small and dull? L4 Analyse
Insect-pollinated flowers must attract insects — colour, scent and nectar serve this purpose. Wind-pollinated flowers do not need to attract anyone; they rely on producing light, abundant pollen that can be blown easily, so they do not "waste" energy on petals or scent.
Assertion–Reason Questions
Options: (A) Both A & R true, R correctly explains A. (B) Both A & R true, R does NOT explain A. (C) A true, R false. (D) A false, R true.
Assertion (A): Sexual reproduction introduces more variation than asexual reproduction.
Reason (R): Sexual reproduction combines DNA from two different parents.
(A) — Both true and R correctly explains A.
Assertion (A): A pollen grain germinates on the stigma to form a pollen tube.
Reason (R): The pollen tube carries the male gamete through the style to the ovule.
(B) — Both statements are true, but R is an additional fact about the role of the tube rather than the reason for its formation.
Assertion (A): The petals of a flower are responsible for making the ovule.
Reason (R): Petals are often brightly coloured to attract pollinators.
(D) — A is false (ovules are formed inside the ovary, not petals). R is true.
Frequently Asked Questions — Sexual Reproduction in Plants
What is sexual reproduction in plants in Class 10 Science (CBSE board)?
Sexual Reproduction in Plants is a key topic in NCERT Class 10 Science Chapter 7 — How Do Organisms Reproduce?. It explains sexual reproduction in flowering plants — flower parts, pollination, fertilisation and seed formation. Core ideas covered include flower, stamen, pistil, anther. Mastering this subtopic is essential for scoring well in the CBSE Class 10 Science board exam because board papers repeatedly test these concepts through MCQs, short answers and long-answer questions. This part gives a complete, exam-ready explanation with activities, diagrams and competency-based practice aligned to NCERT.
Why is flower important in NCERT Class 10 Science?
Flower is important in NCERT Class 10 Science because it forms the foundation for understanding sexual reproduction in plants in Chapter 7 — How Do Organisms Reproduce?. Without a clear idea of flower, students cannot answer higher-order CBSE board questions involving stamen, pistil, anther. Board papers regularly include 2-mark and 3-mark questions on this concept, and competency-based questions often link flower to real-life situations. Building clarity here pays off directly in board marks.
How is sexual reproduction in plants tested in the Class 10 Science CBSE board exam?
The CBSE Class 10 Science board exam tests sexual reproduction in plants through a mix of 1-mark MCQs, 2-mark short answers, 3-mark explanations with examples, 5-mark descriptive questions (often with diagrams or balanced equations) and 4-mark competency-based questions. Expect direct questions on flower, stamen, pistil and application-based questions drawn from NCERT activities. Students who follow NCERT thoroughly and practice this chapter's questions consistently score in the 90%+ range.
What are the key terms to remember for sexual reproduction in plants in Class 10 Science?
The key terms to remember for sexual reproduction in plants in NCERT Class 10 Science Chapter 7 are: flower, stamen, pistil, anther, filament, stigma. Each of these concepts carries exam weightage and regularly appears in the CBSE board paper. Write clear one-line definitions of every term in your revision notes and revisit them before the exam. Linking these terms visually through a flowchart or concept map makes recall easier during the Class 10 Science board exam.
Is Sexual Reproduction in Plants included in the Class 10 Science syllabus for 2025–26 CBSE board exam?
Yes, Sexual Reproduction in Plants is a part of the NCERT Class 10 Science syllabus (2025–26) prescribed by CBSE. It falls under Chapter 7 — How Do Organisms Reproduce? — and is examined in the annual board paper. The current syllabus retains the full treatment of flower, stamen, pistil as per the NCERT textbook. Because CBSE bases every board question on NCERT, studying this part thoroughly ensures complete syllabus coverage and guarantees marks from this chapter.
How should I prepare sexual reproduction in plants for the CBSE Class 10 Science board exam?
Prepare sexual reproduction in plants for the CBSE Class 10 Science board exam in three steps. First, read this NCERT part carefully, highlighting definitions and diagrams of flower, stamen, pistil. Second, solve every in-text question and end-of-chapter exercise — CBSE questions often come directly from NCERT. Third, practice competency-based and assertion-reason questions to sharpen reasoning. Write answers in the exam-style format (point-wise with diagrams) and time yourself. This method delivers confidence and full marks in the board exam.
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