1.7 Genetic Variation and its Control

Question 1

What is variation within a species?

Answer 1

Different organisms of the same species being slightly different

Question 2

What is genetic variation?

Answer 2

An organism being different because of differences in their genes.

Question 3

What is environmental variation?

Answer 3

A difference in an organism as a result of differences in the environment

Question 4

What is the name for a sex cell?

Answer 4

Gamete

Question 5

How many chromosones does the human cell contain?

Answer 5

23 pairs

Question 6

What is a gene?

Answer 6

A short length of a chromosone that controls the development of a characteristic for example hair colour

Question 7

What are chromosones made of?

Answer 7

DNA

Question 8

What is sexual reproduction?

Answer 8

The fusion of male and female gametes which causes offspring with a combination of the parent’s genes

Question 9

What is asexual reproduction?

Answer 9

One individual that clones itself. There is no mixing of genetic material so the offspring is gentically identical

Question 10

What are cuttings and what are they used for?

Answer 10

A bit of a plant is cut off and then planted. This grows a genetically identical plant. Cuttings are used to grow plants quickly and cheaply

Question 11

Name some modern cloning techniques (3)

Answer 11

• Tissue culture
• Embryo transplants
• Adult cell cloning

Question 12

Explain tissue culture

Answer 12

A small group of plant cells are put in a growth medium with hormones so they grow into new plants. This is quick, uses very little space and can be done all year round

Question 13

Explain embryo transplants

Answer 13

1. Sperm and eggs are taken from animals
2. This is artifically fertilised
3. The embryo that develops is split multiple times
4. These embryos are implanted into other animals to give birth

Question 14

Explain adult cell cloning

Answer 14

1. An unfertilised egg cell is taken from an animal
2. The eggs nucleus is removed
3. Another animal’s body cell nucleus is inserted into the empty egg cell
4. The egg cell is stimulated with an electric shock so that it divides
5. The embryos are implanted into animals to give birth

Question 15

How are human genes transferred into other organisms?

Answer 15

The gene is cut out using an enzyme. The other organism’s gene is cut out and the human’s gene is inserted

Question 16

What are GM crops?

Answer 16

Genetically Modified crops are crops that have had their genes modified to make them resistant to viruses, insects or herbicides

Question 17

What are the advantages/disadvantages with GM crops?

Answer 17

Advantages:

• Can increase the yield of the crop, making more food
• GM crops could be engineered to give nutrients that are often lacking in developing nations diet’s
• They’re being grown elsewhere without problems

Disadvantages:

• Could affect the number of weeds/flowers/insects which will reduce biodiversity
• People aren’t convinced they’re safe
• The transplanted genes could get into the natural environment. This could make herbicide resistant weeds