b13- variation and evolution

Question 1

what is variation?

Answer 1

all the differences in the characteristics of individuals in a population

Question 2

variation may be due to differences in:

Answer 2

-the genes they have inherited (e.g blood group)
-the conditions in which they have developed(environmental)
-a combination of genes and the environment (e.g height)

Question 3

is there usually a massive amount of genetic variation within a population of a species?

Answer 3

yes

Question 4

all of this genetic variation is due to?

Answer 4

mutations

Question 5

what are mutations?

Answer 5

random changes to DNA

Question 6

effect of mutations

Answer 6

-most have no effect on the phenotype
-some influence the phenotype
-very few determine the phenotype

Question 7

mutations occur

Answer 7

continiously- very rarely a mutation will led to a new phenotype

Question 8

if the genotype is suited to an environmental change, what can it lead to?

Answer 8

a relatively rapid change in the species

Question 9

what does selective breeding involve?

Answer 9

-choosing parents with desired characteristics from a mixed population
-they are bred together
-from the offspring, those with the desired characteristics are bred together
-this continues over many generations until all offsprings show desired characteristics

Question 10

what is evolution?

Answer 10

a change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species

Question 11

what does the theory of evolution by natural selection state?

Answer 11

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

Question 12

what does evolution occur through?

Answer 12

natural selection of variants that give rise to phenotypes best suited for their environments

Question 13

give an example of evolution

Answer 13

-environment gets colder, rabbits with alleles for thicker fur are more likely to survive that rabbits with thinner fur
-those with thicker fur–>more likely to survive + reproduce

Question 14

if two populations of one species become so different in phenotype what can happen?

Answer 14

they can no longer interbreed to produce fertile offspring- they have formed two new species

Question 15

what is modern medical research exploring?

Answer 15

the possibility of genetic modification to overcome some inherited disorders.

Question 16

problems with genetic engineering:

Answer 16

-some people have ethical objections to genetic engineering
-benefits and risks associated with genetic engineering in agriculture and medicine

Question 17

what is selective breeding?

Answer 17

a process by which humans breed plants and animals for particular genetic characteristics

Question 18

examples of how humans have been doing this for thousands of years

Answer 18

-first bred food crops from wild plants and domesticated animals

Question 19

what are some characteristics that can be chosen for usefulness or appearance?

Answer 19

-diseases resistance in food crops
-animals which produce more meat or milk
-domestic dogs with a gentle nature
-large or unusual flowers

Question 20

selective breeding can lead to interbreeding. what does this mean?

Answer 20

-some breeds are particularly prone to disease or inherited defects

Question 21

What is genetic engineering?

Answer 21

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

Question 22

how have plant crops been genetically engineered?

Answer 22

to be resistant to disease or produce bigger, better fruits

Question 23

how have bacterial cells been genetically engineered?

Answer 23

to produce useful substances such as human insulin to treat diabetes

Question 24

what can happen to the genes from the chromosomes of humans and other organisms in genetic engineering?

Answer 24

they can be ‘cut out’ and transferred to cells of other organisms (e.g bacteria)

Question 25

what are crops that have had their genes modified called?

Answer 25

genetically modified (GM)crops

Question 26

GM crops include ones that are ?

Answer 26

resistant to insect attack or herbicides

Question 27

what do GM crops usually show?

Answer 27

increased yields

Question 28

what do concerns about GM crops include:

Answer 28

-the effect on populations of flowers and insects -some people feel the effects of eating GM crops on human health-not fully explored

Question 29

what is modern medical research exploring?

Answer 29

the possibility of genetic modification to overcome some inherited disorders

Question 30

what is the first step in genetic engineering?

Answer 30

-identify the gene we want to transfer (human gene, another animal or gene from plant)

Question 31

the second step in genetic engineering

Answer 31

enzymes are used to isolate the required gene: the gene is inserted into a vector,usually a bacterial plasmid or a virus

Question 32

the third step in genetic engineering

Answer 32

the vector is used to insert the gene into the required cells

Question 33

the fourth step in genetic engineering

Answer 33

genes are transferred to the cells of animals, plants or microorganisms at an early stage in their development --> so they develop with desired characteristics