Variation and Evolution

Question 1

Variation?

Answer 1

the differences in the characteristics of individuals in a population

Question 2

Phenotype?

Answer 2

physical characteristics

Question 3

What is variation caused by? (3)

Answer 3

• differences in genes inherited (genetic causes)
• the conditions in which the organisms develop (environmental causes)
• or a combination of both

Question 4

Theory of evolution by natural selection?

Answer 4

all species of living things have evolved from simple life forms that first developed over 3 billion years ago

Question 5

Key steps in natural selection?

Answer 5

mutation of gene –> advantage to survival –> breed –> pass on genes

Question 6

Very rarely do mutations lead to a new…

Answer 6

phenotype

Question 7

D. Selective breeding?

Answer 7

speeds up natural selection by selecting animals or plants for breeding that have a required characteristic

Question 8

Desired characteristics for selective breeding?

Answer 8

disease resistance
increased food production
domestic dogs with a gentle nature
heavily scented flowers

Question 9

Problems with selective breeding?

Answer 9

• reduces number of alleles in population
• lack of variation could lead to whole population being wiped out if conditions change
• inbreeding - some breeds are prone to inherited defects or certain diseases or

Question 10

Genetic engineering?

Answer 10

genes transferred to the cells of animals and plants at an early stage of development so they develop desired characteristics

Question 11

Process of genetic engineering?

Answer 11

• genes from chromosomes of organisms ‘cut out’ by enzymes

- transferred o the cells of bacteria and other organisms using a vector ( usually bacteria plasmid or virus)

Question 12

Genetically modified crops also known as…

Answer 12

GM crops

Question 13

GM crops usually have…

Answer 13

improved resistance to insect attacks or herbicides and have a higher yield

Question 14

Examples of GM crops? (3)

Answer 14

• potatoes modified to have more starch
• soybeans modified to produce healthier balance of fatty acids
• some GM grasses absorb and break down explosive residue in soil

Question 15

Benefits of genetic engineering in agriculture? (3)

Answer 15

• improved growth rate in plants and animals
• crops can be designed to grow well in hot/cold/dry parts of the world
• increased food value of crops as GM crops usually have much bigger yields