B14 - Variation and Evolution

Question 1

What is variation?

Answer 1

Variation is the difference in characteristics between individuals.

Question 2

What is variation caused by?

Answer 2

• genes they have inherited
• conditions they have developed under
• combination of genes and the environment

Question 3

Do new genetics make much difference?

Answer 3

Largely no, however a new phenotype sometimes can make an organism better suited to the environment so may become more common in the population.

Question 4

How does evolution happen?

Answer 4

• variation between organisms
• best adapted have advantage
• organisms more likely to survive and reproduce
• pass on useful alleles to offspring
• useful characteristics become more common in population

Question 5

What is selective breeding?

Answer 5

It is the process by which humans
breed plants and animals for particular genetic characteristics.

Question 6

What are the steps of selective breeding?

Answer 6

• parents with desired characteristics are chosen
• they are bred together
• from the offspring, the ones with desired characteristics are chosen
• continues over generations until all offspring show desired characters

Question 7

Why are characteristics chosen?

Answer 7

• disease resistant in food crops
• animals produce more meat or milk
• domestic dogs with gentle nature
• large or unusual flowers

Question 8

What is ‘inbreeding’?

Answer 8

Some breeds are particularly prone to disease or inherited defects.

Question 9

What is genetic engineering?

Answer 9

Involves modify the genome of an organism by introducing a gene from another organism to give a desired characteristic.

Question 10

why do plant crops get genetically engineered

Answer 10

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

Question 11

why has and are bacteria getting genetically engineered

Answer 11

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

Question 12

why are enzymes used in genetic engineering

Answer 12

to cut out the required gene

Question 13

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

Answer 13

vector (e.g., bacterial plasmid or virus)

Question 14

Describe the steps involved in adult cell cloning

Answer 14

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

Question 15

what is tissue culture cloning

Answer 15

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

Question 16

why is tissue cloning of plants important

Answer 16

preserve rare species and for growing plants in commercial nurseries

Question 17

what is cutting as a cloning method

Answer 17

simple method used by gardeners to produce many identical plants from the same parent plant

Question 18

describe cloning through using embryo transplants

Answer 18

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