b13- variation and evolution Flashcards

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1
Q

what is variation?

A

all the differences in the characteristics of individuals in a population

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2
Q

variation may be due to differences in:

A

-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)

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3
Q

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

A

yes

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4
Q

all of this genetic variation is due to?

A

mutations

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5
Q

what are mutations?

A

random changes to DNA

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6
Q

effect of mutations

A

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

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7
Q

mutations occur

A

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

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8
Q

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

A

a relatively rapid change in the species

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9
Q

what does selective breeding involve?

A

-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

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10
Q

what is evolution?

A

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

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11
Q

what does the theory of evolution by natural selection state?

A

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

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12
Q

what does evolution occur through?

A

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

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13
Q

give an example of evolution

A

-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

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14
Q

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

A

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

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15
Q

what is modern medical research exploring?

A

the possibility of genetic modification to overcome some inherited disorders.

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16
Q

problems with genetic engineering:

A

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

17
Q

what is selective breeding?

A

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

18
Q

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

A

-first bred food crops from wild plants and domesticated animals

19
Q

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

A

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

20
Q

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

A

-some breeds are particularly prone to disease or inherited defects

21
Q

What is genetic engineering?

A

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

22
Q

how have plant crops been genetically engineered?

A

to be resistant to disease or produce bigger, better fruits

23
Q

how have bacterial cells been genetically engineered?

A

to produce useful substances such as human insulin to treat diabetes

24
Q

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

A

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

25
Q

what are crops that have had their genes modified called?

A

genetically modified (GM)crops

26
Q

GM crops include ones that are ?

A

resistant to insect attack or herbicides

27
Q

what do GM crops usually show?

A

increased yields

28
Q

what do concerns about GM crops include:

A

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

29
Q

what is modern medical research exploring?

A

the possibility of genetic modification to overcome some inherited disorders

30
Q

what is the first step in genetic engineering?

A

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

31
Q

the second step in genetic engineering

A

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

32
Q

the third step in genetic engineering

A

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

33
Q

the fourth step in genetic engineering

A

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