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Reproduction: How Life Continues

NCERT Class 9 · Science Based on NCERT Class 9 Science textbook · Free CBSE study kit

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Chapter Notes

Overview
This chapter explains how living organisms produce new individuals of their own kind, ensuring the continuity of life on Earth. It covers the two main modes of reproduction—asexual and sexual—detailing processes like vegetative propagation, budding, spore formation, pollination, fertilisation, and human reproduction. The one big idea a student must walk away with is that reproduction, whether asexual (producing clones) or sexual (producing variation), is essential for species survival and adaptation.
Key Concepts (20)
Reproduction
A biological process by which living beings produce new individuals of their own kind.
e.g. A mango tree produces seeds that grow into new mango plants.
Asexual reproduction
A mode of reproduction involving a single parent that produces offspring that are almost exact copies of the parent (genetically identical).
e.g. Yeast cells producing buds that grow into new yeast cells.
Sexual reproduction
A mode of reproduction involving two parents where offspring inherit a mix of characteristics from both individuals.
e.g. Humans giving birth to children who resemble both parents.
Vegetative propagation
A type of asexual reproduction in plants where new plants arise from the vegetative parts (growing parts) of a plant, such as stems, roots, or leaves.
e.g. A potato tuber sprouting new shoots from its eyes.
Budding
A form of asexual reproduction where repeated cell division at a specific site on the parent body produces a small outgrowth called a bud, which enlarges and separates to live independently.
e.g. Hydra producing buds on its body that detach to form new hydra.
Spores
Lightweight, usually single-celled reproductive structures produced in huge numbers by fungi (e.g., mould) that float easily through air currents and germinate into new individuals when moisture and nutrients are available.
e.g. Black patches on bread are mould growing from spores present in the air.
Mitosis
A type of cell division that produces two daughter cells, each having the same number of chromosomes identical to the parent cell; it is the central process behind asexual reproduction.
e.g. When a yeast cell buds, mitosis ensures the bud has the same genetic material.
Meiosis
A special type of cell division that forms gametes, in which the chromosome number of a parent cell (diploid) is reduced to half (haploid) in daughter cells.
e.g. In humans, meiosis produces sperm and egg cells each with 23 chromosomes.
Gametes
Haploid cells used only for reproduction; in animals, male gametes are called sperm and female gametes are called eggs.
e.g. A human sperm cell has 23 chromosomes and fuses with an egg to form a zygote.
Pollination
The transfer of pollen grains from the anther to the stigma of a flower.
e.g. Bees carrying pollen from one sunflower to another.
Self-pollination
The transfer of pollen to the stigma of the same flower or another flower of the same plant.
e.g. Pea plants often self-pollinate before the flower opens.
Cross-pollination
The transfer of pollen from the anther of a flower of one plant to the stigma of a flower of another plant of the same type.
e.g. Maize plants relying on wind to carry pollen between different plants.
Fertilisation
The fusion of male and female gametes (sperm and egg) to form a zygote.
e.g. In flowering plants, the male gamete travels through the pollen tube and fuses with the egg cell in the ovule.
Zygote
The fertilised egg formed after the fusion of male and female gametes, which later develops into an embryo.
e.g. In humans, the zygote has 46 chromosomes and implants in the uterus.
External fertilisation
A method of fertilisation where the female releases eggs into the water and the male releases sperm over them for fertilisation to take place outside the body.
e.g. Frogs and most fish reproduce by external fertilisation in water.
Internal fertilisation
A method of fertilisation where fertilisation takes place inside the body of the female.
e.g. In humans, sperm meets egg inside the female's oviduct.
Ovulation
The release of a mature egg from the ovary, which usually occurs once every month from puberty onwards in human females.
e.g. Around day 14 of a 28-day menstrual cycle, an ovary releases an egg.
Menstruation
The process in which the inner lining of the uterus, along with some blood, sheds and leaves the body through the vagina when an egg is not fertilised.
e.g. A girl's period typically lasts 3 to 7 days each month.
Contraceptive methods
Methods used to prevent unwanted pregnancy, including barriers (condoms), oral pills, Intra-Uterine Devices (IUDs like Copper-T), and surgical methods.
e.g. Using a condom during sexual activity prevents sperm from reaching the egg.
Sexually Transmitted Infections (STIs)
Infections that can be transmitted from an infected person to an uninfected person through sexual contact, including gonorrhoea, herpes, syphilis, genital warts, and HIV.
e.g. HIV can lead to AIDS and is transmitted through unprotected sexual contact.
Formulas & Equations (1)
2^n (where n = number of chromosome pairs)
Reads as: Two to the power n, where n is the number of chromosome pairs
Variables: n = number of chromosome pairs (e.g., for 3 pairs, n=3)
Use when: Calculating the number of possible combinations of chromosomes in gametes due to independent assortment during meiosis
⚠ Students often forget that n is the number of pairs, not the total number of chromosomes. For humans, n=23, not 46.
How It Works
Vegetative propagation by cutting
  1. Cut overgrown branches at the end of the growing season.
  2. Prepare cuttings of shoots in the morning; average length includes several nodes and internodes.
  3. Remove leaves from the lower half of each cutting.
  4. Insert the cuttings up to approximately half their length in soil mixed with compost at an angle of about 45–60° from the soil surface.
  5. Water regularly and observe root and shoot growth.
💡 Cuttings must be taken from the growing parts (shoots) and inserted at an angle to encourage root development.
Grafting
  1. Take a healthy rooted plant (Plant A) and a healthy stem piece from another plant (Plant B).
  2. Create a wound or slit on a twig of Plant A.
  3. Insert and fit the cutting of stem of Plant B into the slit of Plant A.
  4. Protect the wound with a cotton cloth or wrapping film to avoid pests until it heals.
  5. Cut the other branches of Plant A.
  6. Water regularly and observe the growth of Plant B along with Plant A.
💡 Grafting combines two different varieties; the wound must be protected to prevent infection.
Layering
  1. Select a flexible, thin twig of a tree or shrub (e.g., lemon).
  2. Bury the middle part of the twig under the soil surface.
  3. Water regularly and observe new leaves on the buried twig.
  4. After 10–15 days, roots develop from the buried area.
  5. Cut the twig from the parent plant so it can grow as a new plant.
💡 Roots form on the buried portion before separation from the parent.
Budding in yeast and hydra
  1. A small outgrowth (bud) emerges from the parent cell/body.
  2. The bud enlarges through repeated cell division (mitosis).
  3. The bud separates from the parent to live independently.
💡 In hydra, multiple buds can grow on the parent's body at the same time.
Spore formation in fungi (e.g., Rhizopus, Aspergillus)
  1. Spores are formed in a sac-like structure or on a swollen vesicle on fungal hyphae.
  2. Spores are produced in huge numbers (millions from one mould colony).
  3. Spores are lightweight, single-celled, and float easily through air currents.
  4. When spores land on a moist surface with nutrients, they germinate into new individuals.
💡 Spores need warmth and moisture to germinate; refrigeration slows spore growth.
Meiosis and gamete formation
  1. The parent cell (diploid, e.g., 46 chromosomes in humans) undergoes meiosis.
  2. Chromosome number is reduced to half (haploid, e.g., 23 chromosomes in gametes).
  3. Each gamete receives only one chromosome from each pair.
  4. Random mixing of chromosomes creates many combinations (2^n possibilities).
  5. In males, meiosis produces numerous tiny motile sperm; in females, it produces a single large egg.
💡 Meiosis reduces chromosome number by half so that upon fertilisation, the zygote has the correct diploid number.
Pollination and fertilisation in flowering plants
  1. Pollen grains are transferred from anther to stigma (pollination).
  2. Pollen grain germinates on the stigma and produces a pollen tube.
  3. The pollen tube grows down through the style into the ovary.
  4. The male gamete moves through the pollen tube and fuses with the egg cell in the ovule (fertilisation).
  5. The fertilised egg (zygote) develops into an embryo.
  6. The ovary develops into a fruit, and the ovules develop into seeds.
💡 Pollination must occur before fertilisation; without pollination, no fruits or seeds form.
Human fertilisation and pregnancy
  1. During sexual intercourse, millions of sperm enter the vagina and swim through the reproductive tract.
  2. An egg released during ovulation travels from the ovary to the oviduct.
  3. A sperm fuses with the egg in the oviduct to form a zygote.
  4. The zygote undergoes mitotic divisions while travelling to the uterus.
  5. The zygote implants into the thickened inner lining of the uterus (implantation marks beginning of pregnancy).
  6. The embryo develops into a foetus over about nine months (three trimesters).
  7. During childbirth, uterine contractions push the foetus out through the birth canal.
💡 Implantation is essential for pregnancy; if the egg is not fertilised, menstruation occurs.
Menstrual cycle (28-day cycle)
  1. Day 1–5: Menstruation — shedding of the uterine lining.
  2. Day 6–14: Uterine lining gradually rebuilds; an egg starts maturing in the ovary.
  3. Day 14: Ovulation — ovary releases a mature egg.
  4. Day 15–28: Uterine lining becomes thicker and rich with blood vessels.
  5. If no fertilisation occurs, the lining breaks down around day 28 and the cycle repeats.
💡 Ovulation occurs around day 14; the egg remains viable for about one day.
Exam Traps — Don't Make These Mistakes
⚠ Confusing mitosis with meiosis in asexual reproduction
✗ Asexual reproduction involves meiosis because it produces new individuals.
→ Asexual reproduction is based on mitosis, which produces genetically identical daughter cells. Meiosis is used only for gamete formation in sexual reproduction.
✓ Asexual reproduction involves mitosis, a type of cell division that produces two daughter cells with the same number of chromosomes as the parent, resulting in genetically identical offspring (clones).
⚠ Thinking pollination and fertilisation are the same
✗ Pollination is the fusion of male and female gametes.
→ Pollination is only the transfer of pollen from anther to stigma; fertilisation is the actual fusion of gametes (sperm and egg) that occurs after the pollen tube grows.
✓ Pollination is the transfer of pollen grains from the anther to the stigma. Fertilisation is the fusion of the male gamete (from the pollen) with the female gamete (egg) inside the ovule.
⚠ Confusing self-pollination with cross-pollination
✗ Self-pollination occurs between two different plants of the same species.
→ Self-pollination involves the same flower or another flower on the same plant. Cross-pollination involves flowers of two different plants of the same species.
✓ Self-pollination is the transfer of pollen to the stigma of the same flower or another flower of the same plant. Cross-pollination is the transfer of pollen from a flower of one plant to the stigma of a flower of another plant of the same type.
⚠ Assuming all flowers have both male and female parts
✗ Every flower has both stamens and pistil.
→ Some flowers have only stamens (male) or only pistil (female). A complete flower has all four parts: sepals, petals, stamens, and pistil.
✓ A complete flower has four parts: sepals, petals, stamens (male), and pistil (female). However, some flowers may lack either stamens or pistil.
⚠ Thinking the number of chromosomes doubles in sexual reproduction
✗ In sexual reproduction, the offspring has double the number of chromosomes as the parents.
→ Meiosis reduces the chromosome number by half in gametes, so when they fuse, the zygote has the same number as the parents (diploid).
✓ In sexual reproduction, meiosis produces haploid gametes (e.g., 23 chromosomes in humans). Fertilisation restores the diploid number (46 chromosomes) in the zygote, so the chromosome number remains constant across generations.
⚠ Confusing external and internal fertilisation examples
✗ Birds and reptiles use external fertilisation.
→ Birds and reptiles use internal fertilisation; external fertilisation is typical of aquatic animals like frogs and fish.
✓ External fertilisation occurs in water (e.g., frogs, fish), where eggs and sperm are released outside the body. Internal fertilisation occurs inside the female body (e.g., reptiles, birds, mammals).
Compare & Contrast
Number of parents involved
Asexual reproduction
Sexual reproduction
Asexual reproduction involves a single parent; sexual reproduction involves two parents.
Source of pollen
Self-pollination
Cross-pollination
Self-pollination transfers pollen to the stigma of the same flower or another flower on the same plant; cross-pollination transfers pollen from a flower of one plant to the stigma of a flower of another plant of the same type.
Location of fertilisation
External fertilisation
Internal fertilisation
External fertilisation occurs outside the female body (e.g., in water); internal fertilisation occurs inside the female body.
Size and motility
Sperm
Egg
Sperm are very small, produced in millions, actively motile, and have a tail; eggs are large, produced in few numbers, non-motile, and contain stored nutrients.
Exam Focus
Marks pattern: 2 MCQs (1 mark each), 1 Very Short Answer (1 mark), 1 Short Answer (3 marks), 1 Long Answer (5 marks) — total approximately 10-12 marks
Most asked: Differences between asexual and sexual reproduction · Vegetative propagation methods (cutting, grafting, layering) · Structure of a flower and functions of its parts · Pollination types and agents · Fertilisation and seed formation in plants · Human male and female reproductive systems · Menstrual cycle · Contraceptive methods
Don't skip: Draw and label the male or female reproductive system (5 marks); Explain the process of fertilisation in flowering plants (3 marks); Differentiate between asexual and sexual reproduction with examples (3 marks); Describe the menstrual cycle (3 marks)
One-Line Revision (read aloud before the exam)
  1. Reproduction is the biological process by which living beings produce new individuals of their own kind.
  2. Asexual reproduction involves a single parent and produces genetically identical offspring (clones).
  3. Sexual reproduction involves two parents and produces offspring with a mix of characteristics, creating variation.
  4. Vegetative propagation is asexual reproduction in plants using vegetative parts like stems, roots, or leaves.
  5. Cutting, grafting, and layering are artificial methods of vegetative propagation used in agriculture.
  6. Budding is seen in yeast and hydra, where a small outgrowth (bud) grows and separates from the parent.
  7. Spores are lightweight, single-celled reproductive structures produced by fungi that germinate in moist conditions.
  8. Mitosis is the cell division behind asexual reproduction, producing identical daughter cells.
  9. Meiosis reduces chromosome number by half to form haploid gametes (sperm and egg).
  10. A complete flower has four whorls: sepals, petals, stamens (male), and pistil (female).
  11. Pollination is the transfer of pollen from anther to stigma; it can be self or cross.
  12. Fertilisation is the fusion of male and female gametes to form a zygote.
  13. After fertilisation, the ovary becomes a fruit and the ovules become seeds.
  14. External fertilisation occurs in water (e.g., frogs, fish); internal fertilisation occurs inside the female body.
  15. In humans, testes produce sperm and ovaries produce eggs.
  16. Ovulation is the release of a mature egg from the ovary around day 14 of the menstrual cycle.
  17. Menstruation is the shedding of the uterine lining when fertilisation does not occur.
  18. Contraceptive methods include condoms, oral pills, IUDs (Copper-T), and surgical methods.
  19. Sexually Transmitted Infections (STIs) include gonorrhoea, herpes, syphilis, and HIV.
  20. Pregnancy lasts about nine months, divided into three trimesters.

MCQs — 10 Questions with Answers

Q1. Reproduction is defined as the biological process by which living beings produce new individuals. Which of the following best describes the main purpose of reproduction?

  • A. To continue the existence of life on Earth ✓
  • B. To increase the size of individual organisms
  • C. To repair damaged tissues in organisms
  • D. To produce energy for growth

Answer: A — Reproduction ensures species continuation; other options describe growth, repair, or metabolism but not the primary purpose of reproduction.

Q2. A farmer observes that when he plants potato pieces containing eyes (buds), new potato plants grow. This is an example of which type of reproduction?

  • A. Sexual reproduction with two parents
  • B. Asexual reproduction through vegetative propagation ✓
  • C. Budding, the same process as in hydra
  • D. Binary fission similar to bacteria

Answer: B — Potato plant growth from vegetative parts (stem pieces) without seeds is vegetative propagation, a form of asexual reproduction producing genetically identical plants.

Q3. Which of the following statements about asexual reproduction is correct?

  • A. It requires two parents to produce offspring
  • B. It produces genetically identical individuals from a single parent ✓
  • C. It involves mixing of characteristics from two individuals
  • D. It is the primary method of reproduction in all complex animals

Answer: B — Asexual reproduction involves one parent producing genetically identical offspring; sexual reproduction involves two parents and mixing of traits.

Q4. In the grafting technique, a slit is created on Plant A (rooted plant) and a stem cutting from Plant B is inserted. What is the advantage of this process?

  • A. Plant B becomes sexually compatible with Plant A
  • B. Two different plant varieties grow together, combining desirable traits of both ✓
  • C. Plant A produces seeds faster than normal
  • D. The grafted plant becomes immune to all diseases

Answer: B — Grafting allows combining desirable characteristics of two varieties (e.g., disease resistance of one with fruit quality of another) on a single plant.

Q5. Which of the following is NOT a correct statement about vegetative propagation?

  • A. It produces genetically identical plants from a single parent
  • B. It is used extensively in agriculture to propagate desirable crops
  • C. It always produces plants with new genetic variations different from parents ✓
  • D. Methods include cutting, grafting, layering, and tissue culture

Answer: C — Vegetative propagation produces genetically identical offspring without new variations; new genetic variations occur in sexual reproduction where traits mix from two parents.

Q6. Budding in yeast is observed as small round outgrowths (buds) emerging from parent cells. How is budding different from the reproduction in bacteria?

  • A. Budding produces identical offspring while bacterial reproduction produces varied offspring
  • B. Budding is sexual reproduction while bacteria reproduce asexually
  • C. Budding creates a bud that eventually separates, while bacteria split into two equal daughter cells through binary fission ✓
  • D. Budding requires two parent cells while bacteria reproduce with one parent cell

Answer: C — Budding produces an outgrowth that separates as an independent organism, while binary fission in bacteria produces two approximately equal daughter cells by cell division.

Q7. A horticulturist takes a flexible twig from a lemon tree, buries its middle part in soil, waters it regularly, and after 15 days observes roots developing from the buried section. This technique is called:

  • A. Cutting
  • B. Grafting
  • C. Layering ✓
  • D. Tissue culture

Answer: C — Layering involves burying a twig section in soil to develop roots while still attached, then detaching it; cutting and grafting involve different techniques, tissue culture uses cell culture.

Q8. Tissue culture technique revolutionized farming practices in banana production. Which of the following best explains why this technique is advantageous for farmers?

  • A. It allows sexual reproduction to occur in bananas
  • B. It produces mass quantities of healthy, disease-free plantlets from shoot tips, eliminates virus-infected plants, and ensures high yields ✓
  • C. It changes the genetic characteristics of banana plants to make them more productive
  • D. It reduces the need for soil and water in banana cultivation

Answer: B — Tissue culture produces many identical healthy plantlets, removes diseased plants, and guarantees consistent high yields through asexual propagation from disease-free tissue.

Q9. Most complex animals and flowering plants reproduce sexually rather than asexually, even though asexual reproduction is faster. Which of the following is the primary reason for this preference?

  • A. Sexual reproduction is easier to control in laboratories
  • B. Sexual reproduction requires fewer parents so organisms save energy
  • C. Sexual reproduction creates genetic variation through mixing of traits from two parents, enabling populations to adapt to changing environments and evolve ✓
  • D. Sexual reproduction produces more offspring than asexual reproduction

Answer: C — Genetic variation from sexual reproduction allows species to adapt to environmental changes and evolve; asexual clones cannot adapt if conditions change, making sexual reproduction advantageous for complex organisms.

Q10. When preparing cuttings for vegetative propagation, the gardener removes leaves from the lower half of each cutting before inserting it in soil. Which of the following best explains the reason for this practice?

  • A. To reduce water loss through transpiration from buried parts and allow the cutting to focus energy on root development ✓
  • B. To make the cutting lighter so it can penetrate the soil more easily
  • C. To prevent the leaves from rotting and causing fungal infections in the soil
  • D. To speed up the flowering process once roots develop

Answer: A — Removing lower leaves prevents water loss through transpiration from the buried section, allowing the cutting to conserve water and direct energy towards root formation rather than maintaining leaf tissue.

Flashcards

What is reproduction in living beings?

Reproduction is a biological process by which living organisms produce new individuals of their own kind to continue life on Earth.

Define asexual reproduction and give one example.

Asexual reproduction involves a single parent producing genetically identical offspring; example: vegetative propagation in potatoes or yeast budding.

What is vegetative propagation?

Vegetative propagation is a type of asexual reproduction where new plants grow from vegetative parts like stems, leaves, or roots without seeds.

Name three methods of vegetative propagation in agriculture.

The three main methods are: cutting (stem pieces in soil), grafting (joining two plant varieties), and layering (burying twig to develop roots).

What is budding and where does it occur?

Budding is asexual reproduction where a small outgrowth (bud) develops on the parent body and separates to live independently; occurs in hydra and yeast.

Why do farmers prefer asexual reproduction for crop production?

Farmers prefer asexual reproduction because it produces genetically identical plants with desirable traits and ensures consistent quality and higher yields.

Explain the grafting process in plants.

Grafting involves creating a slit on a rooted plant, inserting a stem cutting from another plant variety into it, protecting the wound, and allowing them to grow together.

How does tissue culture help modern agriculture?

Tissue culture produces mass-quantity healthy plantlets from shoot tips, eliminates virus-infected plants, ensures high yields, and revolutionizes farming practices like banana farming.

Why do complex animals and flowering plants use sexual reproduction mainly?

Sexual reproduction produces genetic variation and mixed traits from two parents, enabling populations to adapt to changing environments and evolve new species.

What is the key difference between asexual and sexual reproduction?

Asexual reproduction involves one parent producing identical offspring, while sexual reproduction involves two parents and produces offspring with mixed characteristics.

Important Board Questions

Define asexual reproduction. Name any two methods by which plants reproduce asexually. [2 marks]

Define as single parent producing identical offspring. Name two from: vegetative propagation, budding, binary fission, or specific methods like cutting, grafting, layering, tissue culture.

Explain why farmers prefer vegetative propagation methods like cutting and grafting over growing plants from seeds for cultivating desirable crop varieties. Give two reasons. [3 marks]

Key reasons: produces genetically identical plants preserving desirable traits, ensures consistent quality and high yields, faster multiplication. Do not confuse with sexual reproduction disadvantages.

Describe the process of layering as a method of vegetative propagation. Explain how this technique helps in producing new plants and why it is advantageous compared to growing plants from seeds. Also, suggest one crop where this method is commonly used. [5 marks]

Process steps: select flexible twig, bury middle part in soil, roots develop in 10-15 days, detach from parent. Advantages: genetically identical, no seed dormancy, faster establishment. Examples: lemon, jasmine, guava (any suitable crop).

Assertion-Reason Questions for Reproduction: How Life Continues

Q1. Assertion (A):

Vegetative propagation in plants is a form of asexual reproduction.

Reason (R):

Vegetative propagation involves growth from vegetative parts of a single parent plant and produces genetically identical offspring.

Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true, and the reason correctly explains why vegetative propagation is asexual reproduction. The production of identical offspring from a single parent is the defining characteristic of asexual reproduction.

Q2. Assertion (A):

Tissue culture technique has revolutionised farming practices in banana production.

Reason (R):

Tissue culture produces plantlets from seeds rather than from shoot tips of healthy parent plants.

Answer: C — A is true but R is false — The assertion is true—tissue culture has indeed revolutionised farming by providing mass-produced healthy plantlets. However, the reason is false. Tissue culture uses shoot tips (apical meristem), not seeds. Seeds would involve sexual reproduction, not the asexual tissue culture method.

Q3. Assertion (A):

In grafting, the stock refers to the rooted plant onto which another plant part is attached.

Reason (R):

The stock is the plant that provides the scion, which is the stem piece from the second plant.

Answer: C — A is true but R is false — The assertion is true—the stock is indeed the rooted plant (Plant A) in grafting. However, the reason is false. The stock does not provide the scion; rather, the scion comes from a different plant (Plant B). The stock provides the root system and base support.

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Case-Based Questions (CBQ) for Reproduction: How Life Continues

Case Study:

A strawberry farmer in Himachal Pradesh wanted to increase production of a high-yield strawberry variety called 'Sweet Red'. Instead of growing strawberry plants from seeds (which takes longer and produces genetic variation), he decided to use the runners produced naturally by the strawberry plants. The runners are horizontal stems that emerge from the mother plant, produce leaves and roots at nodes, and can be cut and planted separately as new independent plants. This method allowed him to produce 500 new plants from just 10 mother plants within a single growing season.

Q1. What type of reproduction did the farmer use for strawberry propagation?

  • A. Sexual reproduction through seeds
  • B. Asexual reproduction through vegetative propagation ✓
  • C. Budding reproduction
  • D. Fragmentation reproduction

Answer: B

Q2. Why did the farmer prefer this method over growing from seeds?

  • A. Seeds are more expensive than runners
  • B. To maintain genetic identity and produce identical high-yield plants rapidly ✓
  • C. Because runners contain more nutrients than seeds
  • D. To introduce genetic variation in the strawberry plants

Answer: B

Q3. The runner development in strawberries is an example of:

  • A. Tissue culture propagation
  • B. Grafting technique
  • C. Natural vegetative propagation ✓
  • D. Cutting technique requiring human intervention

Answer: C

Q4. If the farmer had used this method continuously for 10 seasons without changing the parent plants, what potential issue could arise?

  • A. The plants would become too large to handle
  • B. The runners would stop being produced
  • C. The strawberries would lose their sweetness
  • D. Accumulated genetic problems or disease susceptibility could reduce yields ✓

Answer: D

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