B14 Variation and Evolution

Question 1

Variation

Answer 1

Differences in the characterisics of individuals in a population

Question 2

What causes variation

Answer 2

A combination of the genes they have inherited and the environment/ conditions they have developed in

Question 3

Theory of evolution by natuaral selection states

Answer 3

that all species of living things have evolved from simple life forms that first developed more than three billion years ago.

Question 4

What is a genetic mutation

Answer 4

Changes to the sequences of bases in DNA

Question 5

What is Selective Breeding

Answer 5

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

Question 6

What is genetic engineering

Answer 6

This is a process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.

Question 7

What are the three types of cloning:

Answer 7

Tissue culture, cuttings, embryo transplants

Question 8

Describe the process of adult cell cloning

Answer 8

The nucleus is removed from an unfertilised egg cell.
• The nucleus from an adult body cell, such as a skin cell, is inserted into the egg cell.
• An electric shock stimulates the egg cell to divide to form an embryo.
• These embryo cells contain the same genetic information as the adult skin cell.
• When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development.p

Question 9

When is a new species formed

Answer 9

If two populations of one species become so different in phenotype that they can no longer interbreed to produce fertile offspring they have formed two new species.

Question 10

What is inbreeding

Answer 10

where some breeds are particularly prone to disease or inherited defects and this is caused by selective breeding

Question 11

Tissue Culture

Answer 11

using small groups of cells from part of a plant to grow identical new plants. This is important for preserving rare plant species or commercially in nurseries.

Question 12

Cuttings

Answer 12

an older, but simple, method used by gardeners to produce many identical new plants from a parent plant.

Question 13

Embryo Transplants

Answer 13

splitting apart cells from a developing animal embryo before they become specialised, then transplanting the identical embryos into host mothers.

Question 14

Describe the process of genetic engineering

Answer 14

• enzymes are used to isolate the required gene; this gene is inserted into a vector, usually a bacterial plasmid or a virus
• the vector is used to insert the gene into the required cells
• genes are transferred to the cells of animals, plants or microorganisms at an early stage in their development so that they develop with desired characteristics.

Question 15

How have plant crops been genetically engineered

Answer 15

to be resistant to diseases or to produce bigger better fruits.

Question 16

How have bacterial cells been genetically engineered

Answer 16

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

Question 17

What are GM crops?

Answer 17

Crops that have had their genes modified in this way are called genetically modified

Question 18

Concerns about GM crops

Answer 18

Concerns about GM crops include the effect on populations of wild flowers and insects. Some people feel the effects of eating GM crops on human health have not been fully explored.

Question 19

What do GM crops include and what do they cause

Answer 19

GM crops include ones that are resistant to insect attack or to herbicides. GM crops generally show increased yields.

Question 20

What are some modern medical researches exploring with GM crops

Answer 20

possibility of genetic modification to overcome some inherited disorders.