B14 Variation and Evolution

Question 1

What is variation?

Answer 1

differences in the characteristics of individuals in a population

Question 2

What can cause variation?

Answer 2

genetic causes, environmental causes and a combination of genes and the environment

Question 3

How do new phenotype variants occur?

Answer 3

mutations

Question 4

What is selective breeding?

Answer 4

breeding plants and animals for particular characteristics

Question 5

Describe the process of selective breeding.

Answer 5

1. Choose parents with the desired characteristics
2. breed them together
3. choose offspring with the desired characteristic and breed again
4. continue over many generations until all offspring show the desired characteristic

Question 6

What are the consequences of inbreeding?

Answer 6

inherited defects and disease

Question 7

What is genetic engineering?

Answer 7

modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

Question 8

How have plant crops been genetically engineered?

Answer 8

to be resistant to diseases/herbicides/pesticides, to produce bigger fruits, to give higher yields.

Question 9

How have bacteria been genetically engineered?

Answer 9

to produce useful substances, such as human insulin to treat diabetes.

Question 10

What are enzymes used for in genetic engineering?

Answer 10

to cut out the required gene.

Question 11

What is used to transfer the required gene into the new cell in genetic engineering?

Answer 11

vector (e.g. bacterial plasmid or virus)

Question 12

Describe the steps involved in adult cell cloning.

Answer 12

1. nucleus removed from unfertilised egg cell
2. nucleus from adult body cell inserted into egg cell
3. electric shock stimulates egg cell to divide to form an embryo
4. embryo develops and is inserted into the womb of an adult female.

Question 13

What is tissue culture cloning?

Answer 13

using small groups of cells from plants to grow identical new plants

Question 14

Why is tissue culture cloning of plants important?

Answer 14

preserves rare species and useful for growing plants commercially in nurseries

Question 15

What is cutting as a cloning method?

Answer 15

simple method used by gardeners to produce many identical plants from a parent plant.

Question 16

Describe cloning through using embryo transplants.

Answer 16

cells split apart from a developing animal embryo before they are specialised, then, the identical embryos are transplanted into the host mother