Reproduction: How Life Continues | Class 9 Science Notes
By ConceptScroll Team · Published on 17 July 2026 · 5 min read
Reproduction: How Life Continues – this guide gives you a concise, exam-ready overview of Reproduction: How Life Continues from Class 9 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
11.1 Asexual Reproduction
Asexual reproduction is a mode of reproduction in which a single parent produces offspring without the involvement of gametes or sex cells. The offspring produced are genetically identical to the parent, often called clones. This type of reproduction is common in many unicellular organisms such as bacteria, amoeba, and yeast, as well as in simple multicellular organisms like hydra and sponges. Many plants also reproduce asexually through vegetative propagation, where new plants arise from the vegetative parts such as stems, roots, or leaves rather than seeds. For example, potato and ginger plants sprout new plants from their fleshy underground stems. Money plant and sugarcane grow from stem cuttings, and Bryophyllum leaves produce tiny plantlets that grow into new plants. Vegetative propagation is important in agriculture as it allows for the rapid and large-scale production of genetically identical plants with desirable traits. Methods such as cutting, grafting, layering, and tissue culture are used by farmers and horticulturists to propagate plants efficiently. The key advantage of asexual reproduction is its speed and simplicity, allowing organisms to increase their population quickly when conditions are favorable. However, since the offspring are genetically identical, there is less variation, which may reduce adaptability to changing environments.
📊 Diagram: Fig. 11.1: Bryophyllum leaf sprouts tiny plantlet; Fig. 11.2: Cutting; Fig. 11.3: Steps of grafting; Fig. 11.4: Layering; Fig. 11.5: Plant tissue culture.
🧪 Activity: Activity 11.1: Observing cutting, grafting, and layering techniques in plants by interacting with gardeners or farmers and recording observations.
🔗 Connection: Leads to exploring asexual reproduction in unicellular organisms like yeast and hydra, and fungi such as moulds.
Frequently asked questions
(i) Self-pollination (ii) Cross-pollination (iii) Fertilisation (iv) Tissue culture 2. Arrange the following stages of sexual reproduction in plants in the correct order: (i) Pollen germination on stigma (ii) Fertilisation (iii) Pollination (iv) Formation of zygote 3. Assertion (A): The zygote formed after fertilisation immediately attaches to the uterus wall. Reason (R): The uterus wall is always prepared to receive the zygote. (i) Both A and R are true, and R is the correct explanation of A. (ii) Both A and R are true, but R is not the correct explanation of A. (iii) A is true, but R is false. (iv) A is false, but R is true. 4. Why does asexual reproduction produce offsprings that are genetically identical to the parent? 5. Explain why the menstrual cycle stops during pregnancy. 6. Why are flowers that bloom at night white or light in colour as compared to flowers that bloom during the day? 7. Why do vegetatively propagated plants tend to be more vulnerable to diseases than sexually reproduced plants? 8. If all flowers in a type of plant were only capable of self-pollination, how would it affect the genetic diversity over several generations? Explain. 9. A farmer wants to produce a large number of genetically identical plants quickly. Suggest suitable reproduction methods and explain why they are effective.
1. (i) Self-pollination: Pollination occurs within the same flower or between flowers of the same plant. (ii) Cross-pollination: Pollination occurs between flowers of different plants of the same species. (iii) Fertilisation: Fusion of male and female gametes to form a zygote. (iv) Tissue culture: A method of asexual reproduction where new plants are grown from a few cells of a parent plant in a nutrient medium.
2. Correct order: (iii) Pollination → (i) Pollen germination on stigma → (ii) Ferti
10. Suresh prepares slides with pollen grains in different sugar concentrations (0%, 2.5%, 5%, 7.5%, 10%) to study the germination of pollen. (i) What are the different hypotheses which can be tested using this set-up? (ii) What parameters should be kept the same in this set-up?
(i) Hypotheses that can be tested:
- The effect of sugar concentration on pollen germination rate.
- The optimal sugar concentration for maximum pollen germination.
- Whether pollen grains can germinate in the absence of sugar.
(ii) Parameters to keep the same:
- Temperature during the experiment.
- Type and source of pollen grains.
- Duration of pollen exposure to sugar solutions.
- Volume of sugar solution used.
- pH of the sugar solutions if possible.
- Humidity and other environmental condi
11. Look at the picture given below and think in line with the given prompts and find out which type(s) of pollination might have been followed in these flowers — Tomato: Stamens cover the stigma. Wheat: Flowers open after pollination. Papaya: Male and female flowers are often borne on different papaya trees.
Tomato: Since stamens cover the stigma, self-pollination is likely.
Wheat: Flowers open after pollination, indicating cross-pollination.
Papaya: Male and female flowers on different trees indicate cross-pollination (dioecious plants).
12. In the lower Himalayan region of northern India, apples are an important cash crop that contribute significantly to farmer's livelihoods. The fruit yield in apple cultivation is declining continuously, associated with climate change and a significant decline in the population of natural pollinators. A researcher-farmer group set up two experimental apple orchards at two distinct locations: Places A and B. In apple orchards at Place A, they allowed natural pollinators to pollinate the flowers of the apple. In apple orchards at Place B, they applied mixed farming techniques of beekeeping. Along with honey, the farmer yielded apples. The yield of apples is depicted in Fig. 11.24, in terms of fruit setting (number of fruits/the total number of corresponding fruit-bearing branches) and fruit drop (premature falling of developing fruits) in the two types of experimental places of apple orchards. (i) What are the hypotheses the researcher-farmers group has thought of for this investigation? (ii) What are the different parameters in the experiment? (iii) Compare and analyse the data of two experimental orchards Places A and B, in terms of high yields of apple fruits. (iv) Based on your analysis, what do you infer from the data?
(i) Hypotheses:
- The presence of natural pollinators affects apple fruit yield.
- Beekeeping (managed pollinators) increases fruit setting and reduces fruit drop compared to natural pollination alone.
(ii) Parameters:
- Location of orchards (Place A and Place B).
- Pollination method (natural pollinators vs. beekeeping).
- Fruit setting rate.
- Fruit drop rate.
(iii) Analysis:
- Place B (with beekeeping) shows higher fruit setting and lower fruit drop compared to Place A.
- This indicates bet
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