Use of Biological Resources

IGCSE Edexcel Biology
5.1–5.16 Food Production, Microbes, Selective Breeding and GM
Key Concepts: Crop yield can be increased using controlled environments, fertilisers and pest control. Microorganisms are used in food production and industrial fermenters. Selective breeding and genetic modification can improve crops and livestock.

Section A: Crop Production

1. Describe how glasshouses and polythene tunnels increase crop yield. [4]
2. Explain how increased CO₂ and temperature in a glasshouse affect crop yield. [4]
3. Explain how fertilisers increase crop yield. [2]
4. Compare chemical pesticides and biological control (one advantage and one disadvantage of each). [4]

Section B: Microorganisms in Food Production

5. Describe the role of yeast in bread making. [3]
6. Describe the role of Lactobacillus bacteria in yoghurt production. [3]
7. State the conditions required in an industrial fermenter. [5]

Section C: Selective Breeding

8. Describe how selective breeding can develop plants or animals with desired characteristics. [4]

Section D: Genetic Modification

9. State the roles of restriction enzymes and ligase enzymes in genetic engineering. [3]
10. Explain how plasmids or viruses act as vectors. [3]
11. Outline how human insulin can be produced using genetically modified bacteria. [5]
12. Give two ways genetically modified plants can improve food production. [2]
13. Define the term “transgenic.” [2]
Total marks: 44

Mark Scheme

1. Traps heat; protects from weather; allows control of light, CO₂ and pests; extends growing season (any four) [4]
2. CO₂ is a photosynthesis substrate; higher CO₂ increases rate until another factor limits; higher temperature increases enzyme activity to optimum (any four) [4]
3. Adds mineral ions (nitrates, magnesium) to make proteins/chlorophyll, improving growth [2]
4. Pesticides: fast/effective but can kill non-target species and persist; Biological control: targeted/no chemicals but slower and may fail or affect ecosystem (any four) [4]
5. Yeast ferments sugars anaerobically; produces CO₂; CO₂ makes dough rise [3]
6. Lactobacillus ferments lactose to lactic acid; acid coagulates milk to form yoghurt [3]
7. Aseptic conditions, nutrients, optimum temperature and pH, oxygenation (if needed), agitation (any five) [5]
8. Select individuals with desired trait; breed; select best offspring; repeat over generations (plants/animals) [4]
9. Restriction enzymes cut DNA at specific sites; ligase joins DNA fragments [3]
10. Plasmids/viruses carry the gene into cells; used to insert new DNA into host genome [3]
11. Isolate insulin gene; cut plasmid with restriction enzyme; insert gene with ligase; transform bacteria; culture and harvest insulin [5]
12. Increased yield, pest resistance, herbicide resistance, drought tolerance, improved nutrition (any two) [2]
13. Transgenic = genetic material transferred from one species to another [2]