5.4.1Use of Biological Resources
Micropropagation — Edexcel International GCSE Biology 4BI1 Revision Notes & Topical Questions
5 min read 4 parts Lesson 6 of 7 Unit quiz
Part 1 of 4Stages of Tissue Culture
Micropropagation grows many identical plants from tiny pieces of one parent plant, in sterile conditions in vitro.
1
Small pieces of tissue called explants are cut from the parent plant that has the desired features.
2
The explants are sterilised with disinfectant and rinsed with sterile water, to kill microorganisms that would otherwise grow on the nutrient medium.
3
Each explant is placed on sterile nutrient agar in a Petri dish, where its cells divide to form a mass of undifferentiated cells called a callus.
4
The callus is moved to a medium containing plant growth regulators, which make it form roots, shoots and leaves, producing small plantlets.
5
The plantlets are transferred to compost, grown on and later planted out as mature plants.
Part 2 of 4Why It Works
Why It Works
Differentiation
- Differentiation Many plant cells can differentiate into any type of plant cell, so one small piece of tissue can grow into a whole plant.
Clones
- Clones The plants are produced by mitosis, so they are genetically identical to the parent and to each other.
Animals differ
- Animals differ Pieces of animal tissue cannot grow into whole new animals because most animal cells have lost the ability to differentiate.
Sterility
- Sterility Agar is rich in nutrients, so everything must be sterile to prevent bacteria and fungi from overgrowing the cultures.
Part 3 of 4Evaluation
Advantage: quantity
- Advantage: quantity Large numbers of identical plants can be produced quickly and in small space, all year round.
Advantage: quality
- Advantage: quality Plants are disease-free and keep desirable features such as high yield or disease resistance.
Advantage: conservation
- Advantage: conservation Rare or endangered plant species can be reproduced and preserved.
Disadvantage: cost
- Disadvantage: cost Trained staff and a sterile laboratory are needed, which makes the method more expensive than sowing seeds.
Disadvantage: no variation
- Disadvantage: no variation Identical plants share the same weaknesses, so one disease or change in conditions could damage all of them.
Part 4 of 4Exam Checklist & Tips
5.4.1 – Key Points for the Exam
- Micropropagation Growing many identical plants from small pieces of tissue in sterile culture.
- Explant A small piece of tissue cut from a plant for culture.
- Callus A mass of undifferentiated plant cells formed in culture.
- Clone An organism genetically identical to its parent.
- Plant growth regulator A plant hormone added to the medium to make cells develop into roots and shoots.
Common Mistakes
- Forgetting to sterilise the explants and equipment, which allows microorganisms to contaminate the culture.
- Saying the plantlets are sexually produced; they are asexual clones with no variation.
- Writing that micropropagation uses seeds; it uses tissue pieces.
- Calling the callus differentiated;
- a callus is made of undifferentiated cells until growth regulators are added.
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