Biotechnology and Genetic Modification
BiologyΒ· 21.1, 21.2, 21.3Β· 25 min read
1. 1. What is Biotechnology? (Core)β βββββ± 5 min
Biotechnology
The use of living organisms, enzymes, or biological processes to produce useful materials or carry out useful industrial processes.
Example:
Using yeast to make bread is a traditional biotechnology application
Biotechnology includes both ancient traditional uses (e.g. food fermentation) and modern applications (e.g. genetic modification, vaccine production). Bacteria are especially useful in biotechnology and genetic modification because they have a rapid reproduction rate and are able to make complex molecules (syllabus 21.1.1). Core candidates only need to recall 2-3 examples of each type for exam questions.
State two examples of traditional biotechnology applications.
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Step 1: Identify uses that rely on naturally occurring organisms without genetic alteration.
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Step 2: First example: Use of yeast to ferment dough to produce bread.
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Step 3: Second example: Use of lactic acid bacteria to ferment milk to make yoghurt or cheese.
Exam tip:
Core exam questions often ask to distinguish traditional and modern biotechnology, so memorise 2-3 clear examples of each to gain quick marks.
2. 2. Core Biotechnology: Fermentation and Enzyme Usesβ β ββββ± 7 min
Fermentation
The anaerobic respiration of microorganisms (e.g. yeast, bacteria) to produce useful products including alcohol, carbon dioxide, and lactic acid.
Core candidates only need to remember the word equation for anaerobic respiration in yeast: glucose β ethanol + carbon dioxide + small amount of energy. Extended candidates must also learn the balanced symbol equation:
Ethanol for biofuels (21.2.1): yeast respires sugars anaerobically to produce ethanol, which is used as a biofuel.
Bread-making (21.2.2): yeast ferments sugars in dough, producing carbon dioxide that makes the dough rise; the ethanol evaporates during baking.
Two further Core biotechnology uses rely on enzymes rather than on fermentation:
Pectinase in fruit juice production (21.2.3): the enzyme pectinase breaks down pectin in plant cell walls, releasing more juice from the fruit and making the juice clearer.
Biological washing powders (21.2.4): these contain enzymes such as proteases and lipases that break down protein and fat stains, so clothes can be cleaned effectively at lower temperatures.
Explain why dough left in a warm place rises faster than dough left in a cold place.
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Step 1: Link fermentation rate to enzyme activity in yeast cells.
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Step 2: Yeast contains enzymes that control fermentation reactions. Warm temperatures are closer to the optimum for these enzymes, so enzyme activity is faster.
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Step 3: Faster enzyme activity produces more carbon dioxide more quickly, so dough rises faster in warm conditions.
Exam tip:
Always reference enzyme activity and optimum temperature when explaining fermentation rate changes to gain full marks in Core response questions.
3. 3. Genetic Modification (Core + Extended)β β β βββ± 8 min
Genetic Modification (GM)
Changing the genetic material of an organism by removing, changing or inserting individual genes (syllabus 21.3.1). GM is not limited to inserting a gene from another species; when a gene is transferred between species, the organism produced is described as transgenic.
Core: The gene for human insulin production is removed from a human cell. Extended: The insulin gene is cut from human DNA using a restriction enzyme that leaves sticky ends.
Core: The insulin gene is inserted into a circular bacterial DNA called a plasmid. Extended: The same restriction enzyme cuts open a bacterial plasmid, leaving matching sticky ends. DNA ligase enzyme joins the insulin gene to the plasmid.
Core: The plasmid is inserted back into a bacterial cell, which multiplies to produce large amounts of insulin. Extended: The recombinant plasmid is inserted into a host bacterium, which is grown in large fermenters to produce mass quantities of purified insulin for diabetes treatment.
Explain why bacteria are used to produce human insulin.
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Step 1: Recall the two Core reasons bacteria are useful in biotechnology (syllabus 21.1.1).
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Step 2: Bacteria have a rapid reproduction rate, so large populations can be grown quickly to produce high volumes of insulin at low cost.
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Step 3: Bacteria are able to make complex molecules (such as proteins), so once they contain the human insulin gene they can produce human insulin.
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Step 4 (Extended only, 21.1.2): there are few ethical concerns over manipulating and growing bacteria, and their plasmids act as vectors, making it easy to insert the human gene. The bacteria are then grown in large fermenters for continuous insulin production.
4. 4. Evaluating Genetic Modification (Extended Only)β β β β βExtended onlyβ± 5 min
Extended candidates must be able to write balanced evaluations of GM applications for 4-6 mark structured response questions, including both advantages and disadvantages of GM crops and GM insulin.
GM Application | Advantages | Disadvantages |
|---|---|---|
Insect-resistant Bt crops | Reduced insecticide use, higher yields, lower production cost, less harm to beneficial insects from over-spraying | Risk of gene spread to wild plants, risk of insects evolving toxin resistance, unknown long-term health effects, higher seed costs for small farmers |
GM human insulin | Low cost mass production, identical to human insulin so fewer allergic reactions than animal insulin, no ethical issues for people avoiding animal products | High initial development cost, small risk of contamination during production |
Evaluate a farmer's decision to switch to GM herbicide-resistant maize, giving 2 advantages and 2 disadvantages.
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Step 1: Outline 2 evidence-based advantages:
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Advantage 1: The farmer can spray herbicide to kill all weeds without harming maize, increasing yields and reducing weeding labor costs.
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Advantage 2: Reduced soil disturbance from weeding lowers soil erosion risk.
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Step 2: Outline 2 evidence-based disadvantages:
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Disadvantage 1: Herbicide resistance genes may spread to wild weeds, creating hard-to-control 'superweeds'.
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Disadvantage 2: GM maize seeds are more expensive than non-GM seeds, raising initial farm costs, and some buyers may refuse to purchase GM produce.
Exam tip:
Always give balanced points for both sides of GM evaluation questions, and avoid vague statements like 'GM is unsafe' β use specific, syllabus-aligned points to gain full marks.
5. Common Pitfalls
Wrong move:
Writing the balanced symbol equation for fermentation in Core tier answers
Why:
Core only requires the word equation for yeast anaerobic respiration; writing the symbol equation is unnecessary, and errors will lose marks.
Correct move:
Only use the fermentation word equation for Core responses, and only use the balanced symbol equation for Extended tier questions.
Wrong move:
Confusing genetic modification with selective breeding
Why:
Selective breeding uses existing genetic variation within a species over generations, while GM directly changes the genetic material by removing, changing or inserting individual genes (and can transfer a gene between species). Mixing these up loses definition marks.
Correct move:
Explicitly state that GM directly alters an organism's genetic material by removing, changing or inserting genes, while selective breeding uses natural variation within the same species.
Wrong move:
Naming restriction enzymes or DNA ligase in Core GM answers
Why:
These enzyme names are Extended-only content; including them in Core answers is unnecessary, and misnaming them will lose marks.
Correct move:
For Core, describe GM steps without naming enzymes: 'the insulin gene is cut from human DNA and inserted into a bacterial plasmid'.
Wrong move:
Forgetting carbon dioxide is a product of yeast fermentation in bread making questions
Why:
Bread rising relies on carbon dioxide production, not ethanol. Ignoring carbon dioxide will lose application marks.
Correct move:
Always link the relevant fermentation product to the use case: carbon dioxide for bread rising, ethanol for alcohol production.
Wrong move:
Giving one-sided evaluations of GM for Extended questions
Why:
Evaluation questions require balanced arguments to gain full marks; only giving advantages or only disadvantages will cap your mark at half the available points.
Correct move:
Always include at least 2 advantages and 2 disadvantages for any GM evaluation question, with specific context for the application.
6. Quick Reference Cheatsheet
Concept | Core Tier Content | Extended Tier Content |
|---|---|---|
Biotechnology definition | Use of organisms to make useful products | Same as Core, plus distinguish traditional vs modern GM biotech |
Fermentation equation | Glucose β ethanol + carbon dioxide + energy | Same as Core, plus balanced symbol equation |
Core biotechnology uses (21.2) | Ethanol for biofuels, bread-making, pectinase in fruit juice production, biological washing powders | Lactase to make lactose-free milk; fermenters and the conditions controlled in them |
Why bacteria are useful (21.1) | Rapid reproduction rate; able to make complex molecules | Few ethical concerns over manipulation/growth; presence of plasmids |
GM insulin steps | Cut insulin gene, insert into plasmid, grow bacteria to produce insulin | Same as Core, plus mention restriction enzymes, sticky ends, DNA ligase, fermenter use |
GM evaluation | Not assessed | List 2+ advantages and 2+ disadvantages for GM crops and GM insulin |
7. Frequently Asked
Do I need to memorise the balanced symbol equation for fermentation for Core tier?
No. Core tier only requires the word equation for anaerobic respiration in yeast. Extended tier must learn the balanced symbol equation.
What is the difference between genetic modification and selective breeding?
Selective breeding uses naturally occurring genetic variation within a species over many generations. Genetic modification directly changes the genetic material of an organism by removing, changing or inserting individual genes (which may include a gene transferred from another organism) to produce a desired characteristic.
Going deeper
What's Next
Now that you have mastered biotechnology and genetic modification content, you can move on to other Unit 15 topics including sustainable food production and human impacts on pollution. Practice structured response questions to consolidate your knowledge, and make sure you tailor your revision to your tier to avoid unnecessary content. This topic appears frequently in both Paper 3 (Core) and Paper 4 (Extended) exams, so memorise key examples and evaluation points to maximise your marks.