This free quiz has 17 multiple choice questions on cloning and biotechnology, all taken from OCR A Level Biology A exam papers. It marks itself, so you get your score as soon as you finish.
What the quiz covers (OCR A spec 6.2.1)
Natural cloning and taking plant cuttings
Cloning animals, including nuclear transfer
Uses of microorganisms in biotechnology
Advantages and disadvantages of microorganisms in food production
Aseptic technique when culturing microorganisms
Batch fermentation and fermenter design
Bacterial growth curves in a closed culture
Immobilised enzymes
How to use it
Sketch a bacterial growth curve and label its four phases before you start, and jot down a quick list of what a fermenter must control and why. For cloning questions, decide first whether the method is natural or artificial, and plant or animal.
Where students lose marks (from OCR examiners' reports and mark schemes)
Each point below is followed by wording that gained marks.
Cuttings are not micropropagation: Many students described micropropagation when asked about taking cuttings, and described cuttings when the question was clearly about tissue culture, losing most of the marks.
✔ Gains credit: For cuttings, a healthy shoot cut at a slant between nodes, dipped in rooting powder, planted in compost and covered or with some leaves removed; for tissue culture, the idea of multiplying, with many explants taken and calluses subdivided.
Explant and callus, not callose: Common errors were calling the explant a 'cutting', writing 'callose' for callus, describing the mass of cells as an embryo or zygote, and not saying where meristem tissue was taken from.
✔ Gains credit: Removing meristem tissue from a named place such as a shoot tip, sterilising it as an explant, growing it on a culture medium with named nutrients and hormones so cells divide to form a callus.
Split the embryo, not the zygote: Weaker descriptions of embryo splitting referred to splitting the zygote or fertilised egg, and in nuclear transfer many said the egg, zygote or nucleus is implanted into the surrogate.
✔ Gains credit: Splitting an early multicellular embryo of totipotent cells into groups that each develop, and in nuclear transfer, implanting the resulting embryo into a surrogate mother.
Qualify 'quick', 'cheap' and 'easy': Answers on the advantages of microorganisms or plant cloning often just said 'quick', 'cheap', 'easy to grow' or 'large numbers', which gained no credit without explanation.
✔ Gains credit: Specific reasons such as short life cycles and rapid growth, simple nutrient needs, low costs because they work at low temperatures, few ethical concerns, year-round production, and uniform, predictable crops.
Batch versus continuous fermentation: Many students thought secondary metabolites are more likely in continuous fermentation and that growth rate is higher in batch fermentation.
✔ Gains credit: Batch culture uses a fixed volume of medium for a fixed time and is more likely to yield secondary metabolites, while continuous culture adds nutrients and removes product and waste throughout, keeping growth rate high.
Why temperature is controlled: Students often said heat was produced in a fermenter without saying where it came from, and many claimed that 35 °C would denature bacterial enzymes.
✔ Gains credit: Metabolic reactions such as respiration release heat, temperature affects enzyme activity and growth rate, and warmer temperatures near body temperature could encourage the growth of human pathogens.
Nutrients supply named elements: Many students suggested ammonia was a respiratory substrate or killed microbes, or wrote about nitrates in the nitrogen cycle, and few realised that molecules containing only carbon and hydrogen cannot meet all a bacterium's needs.
✔ Gains credit: Identifying the element a nutrient supplies and what it is used for, such as nitrogen for amino acids and proteins or phosphorus for ATP and nucleic acids.
Keep practising
Go on to the Cellular Control and Manipulating Genomes quiz, the Enzymes quiz or the Ecosystems and Populations quiz, or browse all our OCR A Level Biology quizzes. Our OCR A masterclasses (Year 12 on Wednesdays at 5.15pm, Year 13 on Tuesdays at 6.30pm) work through real exam questions on one topic each week.