Feeding the Human Race

Having access to enough safe, nutritious food, all of the time, to live a healthy life.

About 3.0 billion in 1960 and about 7.8 billion in 2020.

Energy is lost between trophic levels, so more crops are needed to make the same amount of food energy as meat.

They tend to eat more meat and dairy foods, and the animals have to be fed on crops.

Global trade and travel carry them, and a warming climate lets them survive in new places.

A strain of wheat stem rust fungus, found in Uganda in 1999, that infects many resistant wheat varieties.

Resistant individuals survive treatment, reproduce and pass on the resistance, so the resistant type becomes common.

Drought, flooding and higher temperatures that shorten or spoil the growing season.

The soil is less fertile, so crop yields fall.

Producing enough food now without harming the ability to produce food in the future.

The things farmers provide or buy, such as seed, fertiliser, pesticide, feed, fuel and water.

Farmers buy less, so crop yields fall and food becomes more expensive.

Increase divided by the original value, multiplied by 100.

Divide the total mass of food produced by the population.

The extra food may not reach the people who need it, or may not keep up with a larger population.

Fertiliser run-off pollutes water and harms ecosystems, which are needed for farming in the long run.

Describe the trend in the world population shown in this graph.

The population rises steadily throughout, from about 3.0 billion in 1960 to about 7.8 billion in 2020, so it has more than doubled. A rising population raises the demand for food.

Nitrate, phosphate and potassium.

To make amino acids and then proteins for growth.

They raise the yield, so more food is produced from the same land.

Too many mineral ions in water, which causes an algal bloom and then a loss of oxygen.

Bacteria use up the oxygen when they break down the dead plants, so the fish suffocate.

A pesticide that kills weeds.

Some are not broken down and build up in the bodies of animals along the chain, and they kill harmless insects as well.

Pests with resistance survive, breed and pass on the resistance.

Growing plants with their roots in a nutrient solution instead of soil.

So that the roots have oxygen for respiration.

Exact control of minerals and conditions, high yields, and crops can be grown where the soil is poor.

It is expensive to set up and run, and a failure or infection can lose the whole crop.

Using living organisms, such as predators, to reduce the numbers of a pest.

The ladybird, or its larvae.

It is slow, it will not remove the pest completely, or the control species may harm other organisms.

They did not control the beetles, but they bred, spread and poisoned native predators.

It makes the crop produce a protein that kills the caterpillars that eat it.

Label the parts of this hydroponics set-up and say what each one does.

The support holds the plants up. The roots take mineral ions from the nutrient solution. The air pump bubbles air through the solution so that the roots get oxygen for respiration. Light is needed for photosynthesis.

Name the parts of the hydroponics set-up marked A, B and C.

A is the roots. B is the nutrient solution (water with mineral ions). C is the air pump.

People choosing parents with wanted characteristics and breeding them for many generations.

Artificial selection.

Decide on the characteristic that is wanted.

Select the ones with the characteristic and breed from them, repeating over many generations.

The plants do not fall over in wind and rain, and more energy goes into the grain.

Higher yield, disease resistance, larger fruit, sweetness or seedlessness.

The wild cabbage (wild mustard).

A high milk yield and resistance to disease.

Breeding hens that lay many eggs, or chickens that grow fast for meat.

Breeding closely related individuals.

It falls, because there are fewer different alleles in the population.

Offspring are more likely to inherit two copies of a harmful recessive allele.

A single disease could infect every plant, because none has an allele for resistance.

Fast-growing chickens may have leg problems, or high-yielding cows may have udder infections.

People choose which organisms breed, instead of the environment.

Increase divided by the starting value, multiplied by 100.

Describe what is happening in this diagram.

In each generation the biggest fruit is chosen as the parent of the next generation. Over many generations the average fruit size increases.

Calculate the percentage increase in milk yield from generation 0 to generation 5.

The increase is 8 600 minus 5 200, which is 3 400 litres. Then 3 400 divided by 5 200, multiplied by 100, gives 65%.

Modifying the genome of an organism by inserting a gene to give it a desirable characteristic.

Genetically modified.

Any species, not only the same species as the recipient.

They cut the gene out of the DNA of the donor.

It makes the protein that the gene codes for.

So that mitosis copies it into every cell of the organism.

The gene is in the genome, so it is inherited by offspring.

To make crops produce a protein that kills caterpillars that eat them.

The farmer can spray the field to kill weeds without killing the crop.

Ringspot virus.

Their bodies cannot make enough, so the blood glucose level rises too high.

The pancreases of pigs and cattle.

The human insulin gene.

In large tanks called fermenters.

It is identical to human insulin, it is cheap and plentiful, and no animals are used.

A gene is moved in one step, instead of choosing parents over many generations.

Describe what is happening at each stage of the diagram.

A gene is found in the DNA of the donor organism. It is cut out using enzymes. It is inserted into the DNA of the recipient cell, so that the recipient makes the protein for the new characteristic.

Describe how insulin is made by genetically engineered bacteria.

The human insulin gene is cut out and put into a bacterium. The bacteria grow in a fermenter, and they make human insulin. The insulin is collected and purified for people with diabetes.

Cuts DNA at a specific sequence of bases.

Short stretches of unpaired bases left at the ends of cut DNA, which can pair with matching ends.

So that their sticky ends are complementary and can pair.

T-T-A-A.

It joins the DNA strands, sealing the gene into the plasmid.

DNA made by joining DNA from two different sources.

A carrier, such as a plasmid, that takes a gene into a host cell.

A small circular loop of DNA in bacteria, separate from the main chromosome.

They are simple, they reproduce very quickly and they can be grown cheaply in fermenters.

No, only a small fraction do.

A gene on the plasmid that lets the bacteria that carry it survive an antibiotic.

Bacteria without the plasmid are killed or cannot grow, while those with it survive.

A visible group of identical bacteria grown from one cell on agar.

Bacteria, which use them to cut up the DNA of viruses.

The selected bacteria are grown in a fermenter, where they multiply and make the protein.

Without it the gene could fall out of the plasmid again.

Describe what is happening in each of the six steps.

1 A restriction enzyme cuts out the gene, leaving sticky ends. 2 The same enzyme cuts the plasmid. 3 DNA ligase joins the gene into the plasmid. 4 The plasmid enters the host bacterium. 5 Only bacteria with the resistance marker grow on antibiotic agar. 6 The bacteria multiply and make the protein.

Name the parts marked A, B and C.

A is a sticky end. B is a plasmid (the vector). C is the host bacterium.

A higher yield and less pesticide, or more nutritious crops, or crops that survive drought.

It makes a protein that kills the caterpillars that eat it.

They can be engineered to tolerate drought, so food can be grown on poorer land.

The spread of a gene to other populations, for example by pollen from a GM crop to a wild relative.

A wild plant could gain resistance to a herbicide and become hard to control.

The toxin or herbicide could harm harmless insects or plants that are not the target.

Resistant pests survive and reproduce, so the resistance becomes more common.

A weed that has become resistant to a herbicide.

It is more costly, and it is often patented, so new seed may have to be bought each year.

The effects on health and ecosystems might take years to show.

It is wrong to alter genomes or to move genes between species, or companies should not own life forms.

It would be wrong not to use a technology that could reduce hunger and malnutrition.

Practical: what will work, cost and happen. Ethical: what is right or wrong.

Pollen from GM crops could cross-pollinate their crops.

It reduces genetic variation, so a new disease could damage the whole crop.

A conclusion that follows from the benefits and risks that have been explained.

Describe one benefit and one risk of GM crops shown in the diagram.

Benefit: the crop makes a protein that kills caterpillar pests, so the farmer needs to spray less. Risk: pollen from the GM crop may fertilise a wild relative, so the gene spreads into wild plants.

Using living organisms, or parts of them, to make useful products.

Fusarium venenatum.

Glucose syrup.

The fungus needs nitrogen to make proteins.

To supply oxygen for aerobic respiration, and to mix the contents.

The fungus releases heat, and the temperature must stay near the optimum of about 30 degrees Celsius.

To stop other microorganisms from growing and spoiling the product.

High in protein and fibre, low in fat, and it needs less land than farming animals.

Some people are allergic to it, or it needs costly equipment and energy.

The thin threads that make up the body of a fungus.

Genetically modified bacteria.

A GM rice that makes beta-carotene in its grains.

The body turns beta-carotene into vitamin A, which reduces vitamin A deficiency.

Ethical or environmental objections to GM crops, or that a varied diet would be a better solution.

It has an extra growth hormone gene, so it grows to market size in about half the time.

To make human proteins, such as antithrombin, in their milk.

Animal welfare, or escaped GM fish breeding with wild fish.

Name each part of the fermenter and say why it is needed.

The inlet at the top left supplies glucose, minerals and a nitrogen source for growth. The air inlet supplies oxygen for respiration and mixes the contents. The cooling jacket keeps the temperature at the optimum. The outlet on the right lets the mycoprotein be harvested.

Name the parts of the fermenter marked A, B and C.

A is the fungus (Fusarium). B is the sterile air inlet. C is the outlet where the mycoprotein is harvested.