B1.7 Genetic Variation and its Control

Question 1

Where are chromosomes found?

Answer 1

In the nucleus of cells

Question 2

What do chromosomes carry?

Answer 2

genes

Question 3

What do genes do?

Answer 3

Control the characteristics of the body

Question 4

Different genes control the development of…

Answer 4

different characteristics of an organism

Question 5

What may differences of different individuals of the same kind be due to?

Answer 5

• genes they have inherited ( genetic causes)
• the conditions in which they developed (environmental causes)
• a combination of both

Question 6

What are the 2 forms of reproduction?

Answer 6

sexual and asexual

Question 7

Describe sexual reproduction

Answer 7

the fusion of male and female gametes. The mixture of the genetic information from 2 parents lead to variety in the offspring.

Question 8

Describe asexual reproduction

Answer 8

No fusion of gametes

only 1 individual is needed as the parent.

There is no mixing of genetic information and so no genetic variation in the offspring. - clone

Question 9

What 2 ways can plants be cloned?

Answer 9

Cuttings- take cutting from other plants- genetically identical.

Tissue Culture- Few plant cells are put into a growth medium with hormones

Question 10

What are the 2 ways to clone animals?

Answer 10

embryo transplants

adult cell cloning

Question 11

Describe an embryo transplant

Answer 11

Sperm and egg cel artificially fertilised

embryo is split many times forming clones, before any of the cells become specialised.

cloned embryos are implanted into host mothers

Question 12

What are gametes?

Answer 12

sex cells

egg, sperm

Question 13

Describe adult cell cloning

Answer 13

The nucleus is removed from an unfertilised egg cell and discarded. The nucleus from an adult body cell is inserted into the egg cell. An electric shock then causes the egg cell to begin to divide to form embryo cells. These embryo cells contain the same genetic information as the adult cell. When the embryo has developed into a few balls of cells, it is inserted into the womb of an adult female to continue its development.

Question 14

What are some issues surrounding cloning?

Answer 14

• reduces the gene pool

- Worried humans may be cloned in the future

Question 15

What are some benefits of cloning?

Answer 15

• Clones lead to a greater understanding of the development of an embryo and of age-related disorders.
• Cloning could be used to preserve endangered species

Question 16

Describe genetic engineering

Answer 16

Genes from the chromosomes of humans and other organisms can be ‘cut-out’ using enzymes and transferred to cells of other organisms at an early stage of their development

Question 17

Describe Genetically modified, GM, crops

Answer 17

Genes are transferred to the cells of plants at an early stage in their development so that they are developed with desired characteristics.

Question 18

Why do farmers grow GM crops?

Answer 18

The crops are often resistant to insect attacks or herbicides therefore, there is an increase in yield

Question 19

What are some concerns with GM crops?

Answer 19

• Uncertainty about effects of eating GM crops on human health.
• Worried will develop allergies for the food.
• affect the number of weeds and flowers and so population of insects that live around the crops, reducing biodiversity.

Question 20

What are some benefits of GM crops?

Answer 20

• increase yield

- GM crop can be developed to contain nutrients that are missing in some people’s diets.

Question 21

What is an advantage of spraying crops with pesticides?

Answer 21

protects crop from being eaten- so more yield produced- more money for farmer

Question 22

What are some disadvantages of spraying crops with pesticides?

Answer 22

expensive

kills other insects which may not be pests

poisonous- could lead to death of a human

Question 23

What is an economic advantage of using GM plants?

Answer 23

reduces the use of pesticides, which are expensive

increase crop yield

Question 24

Should the government allow the production of milk from cloned ‘champion cows’?

Answer 24

• economic benefit - as increase in yield so more profit
• it is not proved that the milk is safe
• ethical/religious argument
• reduces the gene pool

Question 25

What are some advantages of using tissue culture rather than using cuttings to take plants?

Answer 25

more offspring produced

less damage to parent plant

Question 26

Explain why adult cell cloning is a form of asexual reproduction

Answer 26

it involves no mixing of genetic material

because nucleus is removed from the egg cell before fusion

Question 27

What is a gene?

Answer 27

part of a chromosome which controls a characteristic