BiologyICSE Class 8 · Reproduction in Plants and Animals

Asexual Reproduction: Fission, Budding, Fragmentation, Spores, Vegetative Propagation and Tissue Culture

Updated 17 October 2026 · Fact-checked

Asexual reproduction needs only one parent and produces offspring identical to it. Its types are binary fission (Amoeba), budding (yeast, Hydra), fragmentation (Spirogyra), spore formation (Rhizopus), vegetative propagation (potato, Bryophyllum, cuttings, grafting) and tissue culture, where cells in a sterile nutrient medium form a callus and then plantlets.

A tiny piece of one parent grows in sterile nutrient medium into a callus, then plantlets, giving many identical clone plants.

Illustration drawn for QuestionBuddy.

Understand Asexual Reproduction and Tissue Culture

Asexual reproduction. One parent, no gametes, no fusion of cells. Offspring are genetically identical to the parent (clones) and appear quickly.

1. Binary fission. A single-celled organism divides into two equal daughter cells; the nucleus divides first, then the cytoplasm. Examples: Amoeba, Paramecium, bacteria. Numbers double each division: 1, 2, 4, 8, 16, ...

2. Budding. A small outgrowth, the bud, forms on the parent; part of the divided nucleus enters it; it grows and then separates. The two parts are unequal at first. Examples: yeast, Hydra.

3. Fragmentation. The body breaks into pieces and each piece grows into a new individual. Example: Spirogyra.

4. Spore formation. A parent forms many tiny light spores in a case, the sporangium; when it bursts the spores spread through air. Each spore has a tough coat that survives dry weather and germinates on a moist surface. Examples: Rhizopus (bread mould), Mucor, ferns, mosses.

5. Vegetative propagation. New plants grow from a vegetative part (root, stem, leaf), not from a seed.

Part	Example	How it grows
Stem tuber	potato	buds in the eyes sprout
Rhizome	ginger, turmeric	buds on the underground stem sprout
Bulb	onion	buds in the bulb grow
Runner	grass, strawberry	creeping stem roots at nodes
Leaf	Bryophyllum	buds in leaf notches become plantlets
Root	sweet potato, dahlia	buds on swollen roots sprout

Artificial propagation (by people):

Cutting: a stem piece with nodes in moist soil grows roots (rose, sugarcane, money plant).
Layering: a branch is pegged down and covered with soil while attached; when rooted it is cut off (jasmine, grapevine).
Grafting: a scion (cut shoot) is joined to a rooted stock of a related plant (mango, rose).
Advantages: faster than seeds; qualities of the parent are kept; plants that seldom set seed (banana, rose, sugarcane) can be grown.

6. Tissue culture. Growing many plants from a very small piece of tissue in a sterile nutrient medium.
1. A tiny piece of tissue (often from a growing tip) is cut from the parent.
2. It is cleaned and placed on sterile jelly containing sugar, minerals and plant hormones.
3. Cells divide into an unshaped mass, the callus.
4. Pieces of callus on another hormone medium form shoots and roots: plantlets.
5. Plantlets are hardened in pots of soil and then planted out.
Examples: orchids, banana, carnation. Advantages: thousands of identical, disease-free plants in a short time, in any season.

Compare fission and budding.

	Binary fission	Budding
Division	into two equal parts	outgrowth, unequal at first
Example	Amoeba	yeast, Hydra

Flow chart: tissue culture. Tissue piece → sterile medium → callus → shoot and root medium → plantlets → hardening → field.

Asexual Reproduction and Tissue Culture: key facts

Types of asexual reproduction: $F i ss i o n : A m oe ba ∣ B u dd in g : y e a s t, H y d r a ∣ F r a g m e n t a t i o n : S p i r o g y r a ∣ S p or es : R hi z o p u s ∣ V e g e t a t i v e : p o t a t o, B r y o p h y l l u m$; Single parent, identical offspring.
Artificial propagation: Cutting rose
Layering jasmine
Grafting mango (scion on stock)
Tissue culture orchid; Grafting joins two plants.
Tissue culture steps: Tissue piece
Sterile nutrient medium
Callus
Plantlets
Hardening; Sterile means germ-free.

Cutting	rose
Layering	jasmine
Grafting	mango (scion on stock)
Tissue culture	orchid

How to answer Asexual Reproduction and Tissue Culture questions

Match organism to method, state the difference between two methods, or explain the steps and use of tissue culture.

1Spot the clue: two equal cells (fission), outgrowth (budding), broken pieces (fragmentation), sporangium (spores), part of a plant (vegetative).
2For doubling problems, multiply by 2 for each division: after n divisions the number is 2 raised to n.
3Give a named example with every method.
4For tissue culture, keep the order: tissue, medium, callus, plantlets, soil.
5For advantages, link to one parent: offspring are identical, so good qualities are kept.

Asexual Reproduction and Tissue Culture in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Curd bacteria multiplying

Suppose a bacterium in warm milk divides by binary fission once every 30 minutes, and the milk is left for 5 hours.

How many bacteria would descend from one cell, assuming every cell survives and divides?

Try it first, then show the solutionSolution

5 hours = 300 minutes, which is 300 ÷ 30 = 10 divisions.
Each division doubles the number, so the count is 2 multiplied by itself 10 times.
2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 = 1024.

Answer: 1024 bacteria (an ideal case).

Memory hook: Ten doublings make about a thousand.

A good mango variety

Suppose a gardener owns a mango tree whose fruit is very sweet, and wishes to grow more trees with exactly the same sweetness.

Why would she prefer grafting to sowing seeds from the fruit?

Try it first, then show the solutionSolution

A seed grows from a fertilised egg and combines features of two parents, so the new tree may differ.
A graft joins a shoot (scion) of the sweet tree to a rooted stock. The new branches grow from the scion by ordinary cell division, with no gametes involved, so they carry only the sweet tree's characters.
The new branches are therefore identical to the sweet tree.

Answer: Grafting copies the parent exactly, while seeds give a mix of two parents.

Memory hook: Graft to copy, seed to mix.

Tricks to remember Asexual Reproduction and Tissue Culture

Short memory aids. Say each one aloud once, then use it on a question the same day.

Half and half
Fission splits into two equal halves; a bud is a baby on the side.
Use it when: Fission versus budding.
FBFS-V
Fission, Budding, Fragmentation, Spores, Vegetative: the five natural methods in order.
Use it when: Listing methods.
Callus before plantlet
A callus is a cluster of unspecialised cells; hormones then make roots and shoots.
Use it when: Tissue culture steps.

Asexual Reproduction and Tissue Culture: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Right method · 1 mark · MCQBoard level

The reproduction of yeast by forming an outgrowth that separates is called:
(a) binary fission (b) fragmentation (c) budding (d) spore formation

Try it first, then show the solutionSolution

Yeast forms a bud, an unequal outgrowth.

Answer: (c) budding.

Example 2: Two examples each · 2 marks · Short answerBoard level

Name the method of reproduction and one organism that uses it: (a) the body breaks into pieces, each of which grows into a new individual; (b) tiny cells in a sporangium are released into air.

Try it first, then show the solutionSolution

(a) Fragmentation; Spirogyra (1 mark).
(b) Spore formation; Rhizopus (1 mark).

Answer: (a) Fragmentation, Spirogyra. (b) Spore formation, Rhizopus.

Example 3: Doubling · 3 marks · Short answerHarder board level

One Amoeba divides by binary fission every 2 hours. Calculate the number of Amoebae after 12 hours, and the time needed to reach at least 100 individuals from one.

Try it first, then show the solutionSolution

12 hours ÷ 2 hours = 6 divisions, so the number is 2⁶ = 64 (1 mark).
After 6 divisions, 64 is below 100; after 7 divisions 2⁷ = 128, which is above 100 (1 mark).
Time needed = 7 × 2 = 14 hours (1 mark).

Answer: 64 after 12 hours; 14 hours to exceed 100.

Example 4: Why not seeds · 3 marks · Short answerHarder board level

Banana plants of one variety hardly set seed. (a) How can farmers grow more of them? (b) State two advantages of tissue culture over growing plants from seeds.

Try it first, then show the solutionSolution

(a) By vegetative propagation from suckers or by tissue culture (1 mark).
(b) Thousands of plants can be raised from a tiny piece of tissue in a short time (1 mark).
All plants are identical to the parent and free of disease (1 mark).

Answer: (a) Vegetative propagation or tissue culture. (b) Rapid mass production; identical, disease-free plants.

Example 5: Failed tissue culture · 4 marks · Case-basedHOTS / competency

A student prepares a tissue culture of a carnation tip, but the jelly turns cloudy and the tissue dies. (a) Give two precautions he should have taken. (b) After a successful callus stage, which change in the medium is needed for plantlets to form? (c) Why must plantlets be hardened before planting out?

Try it first, then show the solutionSolution

(a) Sterilise the tissue and equipment, and work under germ-free conditions (1 mark).
Keep the container closed and clean so that bacteria and fungi do not grow on the sugar-rich medium (1 mark).
(b) Transfer the callus to a medium with hormones that make shoots and roots (1 mark).
(c) Plantlets are used to the moist, protected glass container and must be gradually adapted to soil and open air (1 mark).

Answer: Sterility is the key; a shoot and root medium is needed; hardening lets plantlets adapt.

Where students lose marks in Asexual Reproduction and Tissue Culture

The slips examiners see most often, and what to write instead.

Mistake: Calling budding in yeast binary fission
Both involve one parent dividing, so students merge them.
Do this: Equal halves are fission; an outgrowth is budding.
Usually costs: 1 mark.
Mistake: Writing tissue culture steps in the wrong order
Plantlets and callus are swapped.
Do this: Tissue piece, sterile medium, callus, plantlets, soil.
Usually costs: 1 mark.
Mistake: Giving no example
Questions say with an example but candidates only define the method.
Do this: Name Amoeba, yeast, Spirogyra, Rhizopus, potato, or orchid.
Usually costs: 1 mark.
Mistake: Saying offspring differ from the parent
Variation belongs to sexual reproduction.
Do this: Asexual offspring are identical to the single parent.
Usually costs: 1 mark.

Exam tips

Give an example with every method.
Tissue culture needs a sterile medium and ends in plantlets that are hardened.
Asexual: one parent, identical offspring.
Doubling questions: count the divisions first.

Practice questions on Asexual Reproduction and Tissue Culture

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · Very short answerBoard level
What is a scion?
Hint
Grafting.
Answer
The cut shoot of the desired plant that is joined to the rooted stock in grafting.
Q2 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Plants grown from the leaf of Bryophyllum are identical to the parent plant.
Reason (R): They are produced from a vegetative part of a single parent without the fusion of gametes.
(a) (A) is true and (R) is false.
(b) (A) is false and (R) is true.
(c) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(d) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
Hint
One parent.
Answer
(c).
Q3 · 3 marks · Short answerHarder board level
A farmer wants to grow sugarcane, ginger and potato. For each, name the part of the plant that he plants, and state two advantages of growing crops this way instead of from seeds.
Hint
Stem cuttings, rhizomes, tubers.
Answer
Sugarcane: a stem piece with nodes (cutting); ginger: a piece of rhizome with buds; potato: a tuber piece with eyes. Advantages: the crop grows faster than from seeds, and every plant is identical to the parent so its good qualities are kept.
Q4 · 3 marks · Long answerHarder board level
Describe how a new plant is obtained by grafting and say why it is useful.
Hint
Scion and stock.
Answer
A cut shoot (scion) of the desired plant is joined to the rooted stem (stock) of a related plant so that they grow together. The new plant has the good qualities of the scion, grows faster than a seedling and can be produced even if the desired plant seldom sets seed.
Q5 · 3 marks · Case-basedHOTS / competency
Read and answer.
Suppose a nursery grows 400 plantlets of an orchid from one tiny piece of tissue.
(a) Name the technique. (1)
(b) Name the first mass of cells formed in the medium. (1)
(c) State one way the plantlets are alike and why. (1)
Hint
Callus.
Answer
(a) Tissue culture. (b) Callus. (c) They are genetically identical to the parent plant, because they arose by repeated cell division from one parent without gametes.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Which organism reproduces by fragmentation?Show answer
Spirogyra.
2.What is the case holding spores called?Show answer
Sporangium.
3.Name the shoot and the rooted part in grafting.Show answer
Scion and stock.
4.Name the mass of cells formed first in tissue culture.Show answer
Callus.
5.Which leaf plant grows from notches on its leaf?Show answer
Bryophyllum.

Asexual Reproduction and Tissue Culture: frequently asked questions

Is vegetative propagation asexual?

Yes. It uses a part of one parent and involves no gametes.

Why is tissue culture called artificial?

It is done in a laboratory by people under controlled conditions.

Do I need all examples?

One reliable example for each method is enough.

Where is sexual reproduction in flowers?

In the next topic, pollination and fertilisation.