Chapter 16 - Agriculture, Medicine, And Genetic Modification

Question 1

Why is it important to increase the amount of food being made?

Answer 1

Because the human population is rising rapidly, and we need to be able to provide those people with food.

Question 2

How to fertilisers increase crop yields?

Answer 2

By providing essential nutrients, especially nitrogen, phosphorus, and potassium (NPK) which are needed by the plant to make proteins and DNA.

Question 3

Why are industrial fertilisers preferential to traditional fertilisers such as manure, in a commercial setting?

Answer 3

Manure breaks down slowly and the minerals become available in the soil, but the balance of NPK varies. Industrial fertilisers make the minerals available immediately and they are perfectly balanced. This ensures that the crop is successful and less time and money is wasted on failed/poor crops.

Question 4

What is a negative consequence of using industrial fertilisers?

Answer 4

Overuse can cause fertiliser to leak into rivers and streams, causing pollution called ‘eutrophication’ that can make the water toxic to humans and animals.

Question 5

Explain what biological control is, and give an example.

Answer 5

Biological control, essentially, is controlling the biological barriers to a successful crop with a good yield. A predator species can be brought in to eradicate pests and/or destructive plants. For example, Chrysolina beetles eat St. John’s wort, which dominates grazing land and causes illness in livestock.

Question 6

Suggest a problem that could arise from introducing a predator species to eradicate pests?

Answer 6

If a predator eats other insects it could disrupt the food chain and cause other pests to become a problem.

Question 7

What is a GMO?

Answer 7

A GMO is a genetically modified organism, made by altering the DNA by inserting the genes from another organism into the original organism.

Question 8

Explain how golden rice is made to contain vitamin A.

Answer 8

It contains a gene from a daffodil and a gene from a bacteria which, together, allow the rice to produce beta carotene (vitamin A).

Question 9

Why was golden rice developed?

Answer 9

To reduce incidences of blindness in populations that are deficient in vitamin a.

Question 10

How is genetic modification being used to increase the number of human organs available for transplant?

Answer 10

Some pugs are currently being bred which have been engineered with some human genes so that their organs are more suitable for use as transplant organs for humans.

Question 11

What is a tissue culture?

Answer 11

The growth of cells or tissues in a liquid or solid nutrient-containing material called a medium.

Question 12

How do cells grow in a tissue culture?

Answer 12

They divide by mitosis, and are therefore clones.

Question 13

How can cells grown in a tissue culture be encouraged to differentiate into specific cell types?

Answer 13

By treating them with hormones.

Question 14

What is a callus?

Answer 14

A clump or sheet of cells grown in a tissue culture.

Question 15

How are tissue cultures used?

Answer 15

• Growing replacement tissues from stem cells

- Studying viruses, as they can only live inside host cells.

Question 16

What precautions should be taken when doing tissue cultures?

Answer 16

They should be done in sterile environments to prevent the growth of bacteria or fungi.

Question 17

Give two problems that selective breeding can cause.

Answer 17

1. Excessive selection can lead to health problems in animals.
2. The variation of a population is reduced, making it vulnerable to disease.

Question 18

Why can farmers produce a better yield from a crop that has been genetically modified to be resistant to herbicides rather than from a non-GM crop?

Answer 18

It allows the crop to be sprayed with.herbicides to kill weeds and other competing plants, so that the yield of the crop increases.

Question 19

Why are people concerned about GMOs?

Answer 19

Some people are concerned that genetically modified plants will spread outside of the crop plants and spread to wild plants with unpredictable consequences.
Some people think that GMOs are harmful to human health, but there is no evidence of this.

Question 20

How can genetically modifying crops to be resistant to herbicides reduce biodiversity?

Answer 20

The herbicides kill plants that other animals and insects require in order to survive.

Question 21

Aphids are another pest that affect the yield of crops. Why might there be more aphids on GM crops than on non-GM ones?

Answer 21

Corn plants have been genetically engineered to produce a toxin that kills off its primary predator: the European corn borer caterpillar. However, this toxin also kills off ladybirds and spiders, but not aphids.Ladybirds are the natural predator of aphids. Fewer ladybirds = more aphids.

Question 22

Give two examples of genetic modification in medicine.

Answer 22

Insulin for type 1 diabetes, and clotting factor 8 for haemophilia.

Question 23

How is genetically modified bacteria made?

Answer 23

1. Genes are removed from human chromosomes (using an enzyme called a restriction enzyme) the enzymes cut the DNA in such a way that one strand is longer than the other. This is known as ‘sticky ends’.
2. The same enzyme is used to cut circular bacterial plasmid, so that the sticky ends on the plasmid can pair with the sticky ends on the human gene. The plasmid is referred to as a vector. The target gene inserts itself into the plasmid with the help of another enzyme- ligase.
3. The recombinant plasmid is then transferred back into the bacteria.The bacteria makes the human protein, which is then purified from the bacterial growth medium.