Topic 4 (Genetic Modification)

Question 1

What is selective breeding?

Answer 1

Select the ones which have the desired characteristics.
Breed them with each other.
Select the best offspring and breed them together.
Continue this process over several generations - the desirable trait gets stronger and stronger, all offspring will have the characteristic.

Question 2

Why is selective breeding useful?

Answer 2

Used in agriculture - to improve meat yields
Medical research- investigating the reasons behind alcoholism - rats bred with a strong and weak preference to alcohol. Allows researchers to compare the differences in their behaviour and the way the brain works.

Question 3

The disadvantages of selective breeding

Answer 3

It reduces the gene pool - the best animals or plants are used and are closely related = inbreeding
Inbreeding can cause health problems as there is a chance of inheriting harmful genetic defects
If a new disease appears as there is less variation there is less chance of resistance alleles, so there is an increased chance that the population could wipe out.

Question 4

Tissue culture

Answer 4

Choose the plant you want to clone based on characteristics.
Remove several small pieces of tissue from parent plant ( from fast-growing root or shoot tips)
Grow the tissue in growth medium containing growth hormones. Done under aseptic conditions to prevent microbes that could harm the plants.
As the tissues produce shoots and roots they can be removed to potting compost.
Fast, produce genetically identical organisms

Question 5

Animal tissue culture

Answer 5

Used in medical research
A sample of tissue is extracted from the animal.
Cells in sample are separated from each other using enzymes.
They are placed in a culture vessels and bathed in a growth medium with nutrients which allows them to grow and multiply.
After cell division, cells can be split up and placed into separate vessels for further growth.
Tissue culture can then be stored.

Question 6

Describe the method of tissue culture a farmer can use to clone his tree

Answer 6

Remove pieces of tissue from fast-growing regions, place the tissue in a growth medium containing nutrients and growth hormones, under aseptic conditions. Once the tissue has grown roots and shoots place the young plant in compost and allow it to grow further.

Question 7

Genetic engineering
What is a restriction enzyme

Answer 7

Recognise the specific sequences of DNA and cuts the DNA at the specific points and then leaves sticky ends where it had been cut

Question 8

What is a recombinant DNA?

Answer 8

Two different bits of DNA stuck together

Question 9

What is Ligase enzymes?

Answer 9

It is used to join two pieces of DNA together at their sticky ends

Question 10

Genetic engineering, how it works?

Answer 10

Plasmid and gene are used.
The DNA you want to insert is cut out with a restriction enzyme. the vector DNA is then cut open using the same restriction enzyme.
It leaves behind sticky ends which are complementary to one another. The ligase then sticks the vector DNA and DNA together to make a recombinant DNA.
It is then inserted into other cells.
Those cells can now use the gene inserted to make the protein

Question 11

Benefits of genetic engineering

Answer 11

Can make crops resistant to herbicides meaning farmers can spray their crops to kill weeds without affecting the crop itself which increases the corp yield.
Can you be used the medicine to genetically engineer bacteria to produce human insulin

Question 12

Disadvantages of genetic engineering

Answer 12

Risk of health problems.
Transplanted genes may get out into the environment which can cause the herbicide resistance to be picked up by weeds creating super weeds.
Adversely affect food chains are even human health

Question 13

Why are crops genetically modified?

Answer 13

To make them resistant to insect pests, which can improve yield.
Plants can produce toxins to prevent being infected with pests but they can develop resistance over time

Question 14

Why can GMOs be used to provide more food?

Answer 14

Population is increasing and food is decreasing. GM crops can increase food production- can grow in drought or resistant to pests.
Can also help combat deficiency diseases eg. Golden rice has a chemical which converts to vitamin A

Question 15

Downsides of GMOs

Answer 15

Many people argue people go hungry because they can’t afford to buy food so they argue that you need to tackle poverty first.
Fears that countries may become dependent on companies who sell GM seeds.
Poor soil is why crops fail so even GM crops won’t survive

Question 16

Other ways to increase food production

Answer 16

Apply fertilisers to increase yields if the soil is poor as they contain minerals that are essential for growth.
This can be controlled without the use of GM crops or chemical pesticides the use of organisms to reduce best numbers.
Biological control can have a longer lasting effect than chemical pesticides and be less harmful to wildlife