Biotechnology — Cambridge IGCSE Biology
Why bacteria are useful, yeast for biofuels and bread, enzymes in industry, and fermenters for making insulin, penicillin and mycoprotein.
Revision notes
4 short notes, in the order of the specification. Each one in short:
Bacteria are useful in biotechnology and genetic modification because they have a rapid reproduction rate and can make complex molecules such as proteins. A large population, and a lot of product, is made in a short time. There are also few ethical concerns over growing them, and their plasmids allow genes to be inserted into them.
Yeast is a single-celled fungus that respires anaerobically when there is no oxygen, breaking down glucose to make ethanol and carbon dioxide. In biofuel production, the ethanol is separated from the tank and used as a renewable fuel. In bread-making, carbon dioxide bubbles are trapped in the dough and make it rise; the ethanol evaporates during baking.
Pectinase, proteases, lipases, amylases and lactase are enzymes used in industry. Pectinase breaks down pectin in fruit cell walls, so more juice is released and it is clearer. Biological washing powders use proteases, lipases and amylases to digest stains into small soluble molecules at low temperatures. Lactase breaks down lactose into glucose and galactose for lactose-free milk.
Fermenters
SupplementA fermenter is a large container in which bacteria or fungi are grown in large numbers to make a useful product, such as insulin, penicillin or mycoprotein. Temperature and pH are kept at the optimum for the microorganisms' enzymes, sterile air supplies oxygen for aerobic respiration, nutrients are added, and waste products are removed, giving a high yield.
Exam questions
8 exam-style questions (26 marks), each with its mark scheme.
Answer the questionsFlashcards
17 cards: flip them, mark what you knew, and practise the rest.
Practise the cardsMind map
The whole of biotechnology and genetic modification on one page, so you can see where this subtopic fits.
Open the mind mapPractical sheet
Method, variables, risks and a results table, with questions to answer.
Print it
Free PDFs to print or save.
Quick check questions
Give two reasons why bacteria are useful in biotechnology.
Show answer
They reproduce rapidly; they can make complex molecules (such as proteins).
Which gas makes bread dough rise?
Show answer
Carbon dioxide, from anaerobic respiration in yeast.
What does pectinase do in fruit juice production?
Show answer
Breaks down pectin in cell walls, so more juice is released and it is clearer.
Supplement What does lactase break lactose into?
Show answer
Glucose and galactose.
Supplement Why is oxygen supplied to a fermenter?
Show answer
For aerobic respiration, to release energy for growth and making the product.
Frequently asked questions
Why are bacteria used in biotechnology?
Bacteria are used in biotechnology because they have a rapid reproduction rate, so a large population and a large amount of product are made in a short time. They can also make complex molecules, such as proteins, that are difficult to make in other ways. Once genetically modified, they can make human proteins such as insulin.
How does yeast make bread rise?
Yeast makes bread rise by respiring anaerobically in the warm dough and producing carbon dioxide. The carbon dioxide forms bubbles that are trapped in the dough, which makes it rise. When the bread is baked, the bubbles expand, the yeast is killed and the dough sets with air spaces. The ethanol evaporates.
How do biological washing powders work?
Biological washing powders contain enzymes that digest stains into small, soluble molecules that wash out. Proteases break down protein stains such as blood or egg into amino acids, lipases break down fats into fatty acids and glycerol, and amylases break down starch into sugars. They work well at low temperatures such as 30 to 40 °C.
Why is pectinase used in fruit juice production?
Pectinase is used because it breaks down pectin, which helps hold plant cells together in their cell walls. Added to crushed fruit pulp before pressing, it breaks down the cell walls, so more juice is released and the yield is higher. The juice is also clearer, because less pectin is left in it.
What conditions are controlled in a fermenter?
Supplement A fermenter controls temperature, pH, oxygen, nutrient supply and waste products. Temperature and pH are kept at the optimum for the microorganisms' enzymes, using a water jacket and probes. Sterile air supplies oxygen for aerobic respiration. Nutrients such as glucose provide energy and raw materials, and waste gases leave through an outlet.
Written and checked against the Cambridge IGCSE Biology (0610) specification · Updated October 2026