6.2.4Global Challenges
Biotechnology and Human Population — OCR Gateway GCSE Combined Science A J250 - Biology Revision Notes & Topical Questions
5 min read 10 parts Lesson 8 of 18
Part 1 of 8Food security and a growing population
The world population has grown to more than eight billion people. Food security means that everyone has enough safe, nutritious food.
Biotechnology
Factors that threaten food security include a rising population, climate change, pests and plant disease, water shortage, poverty and food waste,
- and the increase in demand for meat,
- which is an inefficient use of land because energy is lost between trophic levels. Biotechnology is the use of living organisms, or their products, to make things people need.
It can help raise the quantity and quality of food.
Part 2 of 8Fermentation and microorganisms in food
Many foods depend on microbes.
Fermentation and microorganisms in food
Yeast respires anaerobically to make carbon dioxide, used in bread, and ethanol, used in beer and wine.
Bacteria such as Lactobacillus ferment lactose in milk to lactic acid to make yoghurt and cheese; the acid lowers the pH,
- which curdles the milk and helps to preserve it.
Fermenters,
- which are large steel vessels, provide ideal conditions on an industrial scale: temperature, pH, oxygen levels and nutrients are monitored and controlled,
- and the equipment is sterilised to avoid contamination.
The temperature has to be kept at the optimum for the enzymes of the microorganism. In many fermenters a water jacket carries away heat produced by respiration, and a paddle stirs the culture to spread nutrients and oxygen evenly.
Part 3 of 8Mycoprotein
Mycoprotein is protein-rich food made from the fungus Fusarium.
1
The fungus is grown in a fermenter on glucose syrup as a source of carbon and energy, with added nitrogen compounds, in aerobic conditions with carefully controlled pH and temperature.
2
The mycelium is harvested, heated to reduce the amount of nucleic acid, then processed into meat substitutes.
3
Advantages: high in protein, low in fat, no cholesterol and suitable for vegetarians; it grows fast and uses much less land and water than animal farming, with fewer food-chain energy losses.
4
Disadvantages: the taste and texture require added flavourings, the process requires energy and sterile equipment,
- and some people find the idea unappealing.
Part 4 of 8Genetically modified crops
In genetic engineering, a gene for a useful characteristic is cut from the DNA of one organism and inserted into the cells of another, often with a bacterial plasmid or virus as a vector.
Genetically modified crops
The modified plant then makes the new protein.
Examples: Bt maize, with a bacterial gene for an insect toxin; golden rice, with genes giving beta-carotene,
- which the body converts to vitamin A, to prevent deficiency;
- crops tolerant of herbicides or of drought, and crops with a longer shelf life.
| Possible benefits | Possible concerns |
|---|---|
| Higher yield and less pesticide use | Possible effect on other organisms, such as pollinators |
| Added nutrients | Gene spread to wild relatives by pollen |
| Can grow in poor conditions | Cost, and seed owned by companies; unknown long-term health effects |
Part 5 of 8Wider issues
Biotechnology cannot solve food shortage by itself.
1
Distribution, cost and waste matter as much as production, and farming practices such as monoculture reduce biodiversity.
2
Other approaches include reducing food waste, sustainable fishing quotas, and eating lower in the food chain.
3
When evaluating a method for feeding more people, consider the efficiency of energy transfer, the environmental cost, ethics and who gains.
4
The same techniques are used in medicine, as described in the lesson on gene technology.
Part 6 of 8Fermentation calculations and interpretation
You may be asked to read a graph of the mass of mycoprotein produced against time.
Fermentation calculations and interpretation
In the early part of the graph, the fungus grows slowly while it adapts to the medium; growth then becomes rapid as nutrients and oxygen are plentiful; finally the curve levels off as nutrients run out or waste products build up.
The rate of growth can be found from the gradient: if the mass rises from 20 g to 80 g in 12 hours, the mean rate is 60 / 12 = 5 g per hour.
You may also compare yields: if a fermenter makes 12 tonnes of protein from 100 tonnes of glucose, the conversion is 12%,
- and you might compare this with the 10% efficiency of energy transfer between trophic levels to judge whether the method is competitive.
Part 7 of 8Comparing ways to produce protein
| Source | Land and water use | Speed | Issues |
|---|---|---|---|
| Beef cattle | High | Months or years | Energy loss at each level; methane |
| Soya or pea crops | Moderate | One season | Land use, possible monoculture |
| Mycoprotein | Low | Hours to days | Needs sterile equipment, energy and a feed source |
A comparison like this gives you the evidence to support a conclusion in a longer answer.
Part 8 of 8Exam-style questions
Explain why mycoprotein production needs a fermenter with controlled temperature and pH. [3]3 marks
Exam-style questions1. The fungus has enzymes with an optimum temperature and pH for growth. [1]2. Too hot or wrong pH would denature enzymes and reduce the growth. [1]3. Controlled conditions give a high, reliable yield and prevent other microbes from competing. [1]Describe the steps involved in making a genetically modified crop that resists insects. [3]3 marks
Exam-style questions1. Identify and cut out the gene for the insect toxin from the bacterial DNA (using enzymes). [1]2. Insert the gene into the plant cells using a vector such as a plasmid. [1]3. Grow the plant cells into whole plants that express the toxin. [1]Suggest why producing protein from mycoprotein may be more efficient than rearing cattle. [2]2 marks
1. Fungus is directly grown on glucose, so there are fewer energy losses between trophic levels than in feeding crops to cattle. [1]
2. It grows quickly and uses less land. [1]
Key terms
| Term | Meaning |
|---|---|
| Biotechnology | The use of living organisms to make useful products. |
| Fermenter | A vessel where microorganisms are grown under controlled conditions. |
| Mycoprotein | Protein-rich food made from a fungus. |
| Genetic engineering | Transferring a gene from one organism to another. |
| Vector | A carrier, such as a plasmid, used to transfer genes. |
| Food security | Having enough food that is safe and nutritious for everyone. |
| Anaerobic respiration | Release of energy from glucose without oxygen. |
| Monoculture | Growing a single crop over a large area. |
Avoid these mistakes
1
Saying that GM crops are produced by selective breeding. Genes are transferred directly in genetic engineering.
2
Calling mycoprotein a plant protein; it comes from a fungus.
3
Stating that yeast makes lactic acid in yoghurt; that is bacteria.
4
Giving one-sided answers in evaluation questions; include both a benefit and a concern.
5
Forgetting that fermenters need to be sterile to avoid contamination.
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