Tissue culture is used to produce large numbers of genetically identical plants from small samples taken from a parent plant. Explain why plants produced in this way are genetically identical to the parent plant.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A horticulturalist takes small samples from a single rose plant that produces unusually large, fragrant flowers. These samples are then grown in a sterile nutrient medium under controlled conditions to produce hundreds of new plants.
Model answer (4 marks)
The explants are taken from the parent plant, so they contain cells that have the same DNA as the parent.
The cells in the explants undergo mitosis to form new cells.
Mitosis produces daughter cells with the same chromosome number and the same genetic information as the parent cell.
Thus every new plant that grows from the explants has the same genotype as the parent plant – they are clones.
The cells in the explants undergo mitosis to form new cells.
Mitosis produces daughter cells with the same chromosome number and the same genetic information as the parent cell.
Thus every new plant that grows from the explants has the same genotype as the parent plant – they are clones.
Examiner tips
- State that explants contain parent cells, mention mitosis, and conclude that the genotype is identical.
- Use the exact wording ‘genetic information’ and ‘same number of chromosomes’ as the mark scheme.
- Show the logical sequence: explants → mitosis → identical DNA → clones.
Common mistakes
- Confusing mitosis with meiosis or ignoring that mitosis keeps chromosome number unchanged.
- Failing to mention that the explants are taken from the parent plant.
- Using vague terms like ‘similar’ instead of ‘identical’ for the genetic information.
Mark scheme (4 marks)
- The small samples (explants) contain cells from the parent plant
- The cells divide by mitosis (to produce new cells)
- Mitosis produces cells with the same genetic information / same number of chromosomes as the parent cell
- Therefore all new plants have the same genetic information / genotype as the parent plant, so they are clones
Key terms in this question
Related
- All Pearson Edexcel International GCSE Biology (4BI1) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Cloning questions
- Explain why the offspring produced by cloning a mammal using somatic cell nuclea…
- Describe the process of micropropagation used to produce large numbers of geneti…
- Describe the roles of the enucleated egg cell and the diploid nucleus in the pro…
- Explain why a diploid nucleus is used, rather than a nucleus from a gamete, when…