b14 - variation and evolution

Question 1

give three reasons for variation

Answer 1

• differences in the genes they have inherited
• conditions in which they have developed
• combination of genetic and environmental causes

Question 2

what controls appearance of an individual?

Answer 2

genes

Question 3

how might plants be affected?

Answer 3

• lack of light
• nutrients
• space to grow

Question 4

what happens if a plant is deprived of nutrients?

Answer 4

it cannot grow as well as other plants with same genes growing in better conditions

Question 5

how would a pregnant mother smoking and drinking affect baby?

Answer 5

may have low birthweight

Question 6

why would individual organisms show a wide range of variation?

Answer 6

due to differences in genes

Question 7

what do organisms in a population compete for?

Answer 7

• food
• shelter
• predators
• mates

Question 8

which organisms are more likey to survive?

Answer 8

• if they are more suited to a certain environemt
• more likely to breed successfully

Question 9

define a mutation

Answer 9

when a gene changes and becomes a new form

Question 10

where are mutations important?
give an example

Answer 10

• in natural selection if environment changes
• rabbit disease mxyomatosis killed most rabbits in UK
• some had a mutated disease that gave immunity so these ones survived then bred and rabbit population became immune to disease

Question 11

how does a new species evolve through natural increase?

Answer 11

if a population changes so much so they can no longer breed with another population to produce fertile offspring.
- this takes millions of years

Question 12

when could evolution of a population occur in a relatively short time?

Answer 12

e.g if bacerium has a mutation to make it resistant to antibiotics then this mutation can spread rapidly through population until all bacteria are resistant

Question 13

give key steps of natural selection

Answer 13

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

Question 14

give three examples of animals or plants with desired characteristics

Answer 14

• cows that produce the most milk to breed next generation of dairy cattle
• high yielding cows may be crossed with bulls of mis temperament
• seeds are selected from plants with the biggest grain to grow next crop

Question 15

define selective breeding

Answer 15

farmers and breeders select animals or plants with desired characteristics

Question 16

give some features that selective breeding is used to select for

Answer 16

• disease resistance in food crops or garden plants
• animals producing more meat or milk
• domestic dogs and farm animals with gentle nature
• large, unusual, brightly coloured or heavily scented flowers

Question 17

why are some animals cross-bred?

Answer 17

• two desireable traits
• offspring that shows both of favourable features will be selected

Question 18

give some limitations of selective breeding

Answer 18

• greatly reduces number of alleles in population
• less variation between individuals in population
• new disease or climate change could destroy whole population
• inbreeding of related organisms, such as breeds of dogs, led to inherited defects

Question 19

define genetic engineering

Answer 19

involving change of genetic make up of an organism

Question 20

define process of genetic engineering

Answer 20

1) desired gene ‘cut out’ of chromosome using an enzyme
2) then inserted into chromosome of another organism, vector transfers gene

Question 21

what happens when human gene produces to produce insulin is inserted into bacteria?

Answer 21

bacteria produces large quantities of insulin to treat diabetes

Question 22

how are genes cut out of chromosomes to make an insulin gene?

Answer 22

cut out of DNA by an enzyme

Question 23

what is a crop with changed genes referred to?

Answer 23

• genetically modified, GM crop plants

Question 24

what can a GM crop do?

Answer 24

make its own pesticide, or hebicide resistant, usually has increased yields

Question 25

give 5 benefits of using genetic engineering

Answer 25

• correct gene can replace faulty gene to prevent genetic disorder
• medical drugs like insulin, human growth hormone and antibodies produces
• GM crops are resitant to herbicide, can be killed without damaging effects
• GM crops can grow well in dry, hot, or cold parts of the world
• genetic technology improves growth rate of plant animals

Question 26

give 5 concerns of genetic engineering

Answer 26

• infertile GM crops meaning new seeds required every year
• concerns around intoducing genes into wild flower populations
• insects, not pests, may be affected by GM crops
• ## insects could become resistant to pesticides

Question 27

what are ethical issues of genetic engineering?

Answer 27

• what will be the long term effects?
• might we create new organisms that we no nothing about?
• are these processes ethically acceptable?