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BIOLOGY > Natural Selection and Genetic Modification > Flashcards

Natural Selection and Genetic Modification Flashcards

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1
Q

what is evolution

A

the slow and continuous change of organisms’ inherited characteristics from one generation to the next

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2
Q

explain how evolution occur by natural selection

A
  1. Individuals in a population show genetic variation as they have different alleles
  2. Predation, competition for resources and disease act as selection pressures which means they affect an organisms chance of surviving and reproducing
  3. Individuals with characteristics that make them better adapted to the selection pressures have a better chance of surviving
  4. This means alleles responsible for the useful characteristics are more likely to be passed onto the next generation
  5. Some individuals will be less adapted to the selection pressures and will be less able to compete, survive and reproduce
  6. Beneficial characteristics become more common in the population over time
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3
Q

what are antibiotics

A

drugs designed to kill bacteria or prevent them from reproducing

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4
Q

how does the emergence of resistant organisms support the theory of evolution

A

the emergence of antibiotic resistance proves evidence for evolution . Antibiotic reisstance makes the bacteria better adapted to an environment in which a selection pressure (antibiotics) are present. As a result, antibiotic resistance has become more common in the population over time

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5
Q

what is evidence for evolution

A

fossils

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6
Q

how do fossils prove evidence for evolution

A

by arranging fossils in chronological order, gradual changes in organisms can be observed which shows how organisms have changed and developed

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7
Q

what did Charles Darwin do that led him to the theory of evolution

A

he spent 5 years on a voyage around the world. He noticed there was variation in member of the same species and that those with characteristics most suited to the environment were more likely to survive and pass on the characteristics to offspring.

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8
Q

what did Wallace realise that led him to the theory of evolution

A

Wallace realised that warning colours are used by some species to deter predators from eating them - an example of a beneficial characteristic that had evolved by natural selection

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9
Q

what is the influence of the theory of evolution on modern biology

A

it has helped us classify organisms based on how closely related they are

we now understand the importance of finishing the course of drugs to prevent resistant bacteria spreading

We now understand the importance of genetic diversity and how it helps populations adapt to changing environments

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10
Q

what is “Ardi”

A

a fossil of the species Ardipithecus ramidus which is 4.4 million years old

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11
Q

what are the features of “Ardi”

A

the structure of her feet suggest she climbed trees as she had an ape like big toe

she also had large arms and short legs

her brain size was about the same as a chimpanzee

the structure of her legs suggests she walked upright

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12
Q

what is Lucy

A

a fossil of the specied Australopithecus afarensis, which is 3.2 million years old

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13
Q

what are the features of “Lucy”

A

she had arched feet, more adapted to walking than climbing

size of arms were in between an apes and humans

brain was slightly larger than Ardi’s but still around the same size as a chimpanzee

the structure of Lucy’s legs bones and feet suggest she walked upright but more efficiently than Ardi

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14
Q

what did Richard Leaky find

A

different Australopithecus and Homo species, including Turkana boy which is 1.6 million years old

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15
Q

what are the features of “Turkana boy”

A

he had short arms and long legs much like a human and his brain size was much larger than Lucy’s - similar to a human

The structure of his legs and feet suggest he was even better adapted to walking upright than Lucy

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16
Q

What stone tools did Homo Habilis use (between 2.5-1.5 million years ago)

A

they made simple stone tools called pebble tools by hitting rocks togehter to make sharp flakes

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17
Q

what stone tools did Homo erectus use (between 2 and 0.3 million years ago)

A

they sculpted rocks into shapes to produce more complex tools like simple hand axes which are used to hunt, dig, chop

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18
Q

what stone tools did Homo neanderthalenis use (300,000 and 25,000 years ago)

A

they used flint tools, with sharp,pointed edges and wooden spears

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19
Q

what stone tools did Homo Sapiens use (200,000 years ago to now)

A

more complex pointed tools including fish hooks, needles and arrowheads were used and flint tools were widely used as well

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20
Q

how can you date stone tools and fossils

A

looking at the structural features of the tool or fossil

using stratigraphy

carbon-14 dating

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21
Q

what is stratigraphy

A

the study of rock layers

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22
Q

what is a limb

A

an arm, leg or wing

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23
Q

what is a digit

A

the end part of a limb e.g. a finger or a toe

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24
Q

what is a pentadactyl limb

Study These Flashcards
A

a limb with 5 digits

25
how does the anatomy of the pentadactyl limb prove evidence for evolution
the similarity in bone structure proves evidence that all species with a pentadactyl limb have all evolved from a common ancestor. If they had all evolved from different ancestors, it would be highly unlikely that they would share a similar bone structure
26
what are the 5 kingdoms
animals plants fungi prokaryotes - all single celled organisms without a nucleus eukaryotes
27
what are kingdoms divided into to make smaller groups
kingdom phylum class order family genus species
28
what are the 3 dominions
eukarya archaea bacteria
29
what is selective breeding
when humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population
30
what are examples of selective breeding
animals that produce more meat or milk crops with disease resistance dogs with a good, gentle temperament plants that produce larger fruit
31
what is the basic process of selective breeding
1. From your existing stock, select the ones with the desirable characteristics 2. Breed them with each other. 3. Select the best of the offspring and breed them together 4. Continue this process over several generations and the desirable trait gets stronger and stronger and eventually all offspring will have the characteristic
32
what are the benefits of selective breeding
higher yields selective breeding can be used in medical research
33
what are the risks and negatives of selective breeding
it reduces the gene pool and number of allele in a population inbreeding can cause health problems because there is more chance of organisms inheriting harmful genetic defects ethical considerations as animals are deliberately bred to havbe negative characteristics for medical research if a new disease appears they are all likely to be killed by it if one dies as there is not much variation so less chance of resistant alleles
34
what is tissue culture
when cells are grown on or in an artificial growth medium
35
what is the growth medium
usually agar jelly
36
what are clones
genetically identical organisms
37
why do scientists use tissue culture
to produce lines of clones all with the same beneficial features
38
explain the process of tissue culture
1. First choose the plant you want to clone, usually based on its characteristics 2. Remove several pieces of tissue from the parent plant 3. Grow the tissue on a growth medium containing nutrients and growth hormones 4. As tissues produce shoots and roots they can be moved to potting compost to carry on growing
39
what are the advantages of tissue culture
it is easy plants can be made very quickly doesn't take up a lot of space can be grown all year
40
what is genetic engineering
transfer of a gene from one organisms genome into another organism's genome in order to introduce a desirable characteristic
41
what is genetic engineering used to do
produced GM crops produce human insulin from bacteria to treat diabetes
42
explain the process of genetic engineering
1. The DNA that is going to be transferred is cut out with a restriction enzyme. The cut leaves one of the DNA strands with unpaired bases - this is called sticky ends 2. The SAME restriction enzyme is used to cut open the vector DNA. It could be a plasmid or a virus. 3. The vector DNA and the DNA you are inserting are left with complementary sticky ends . They are mixed together with ligase enzymes . 4. Ligase joins the sticky ends togheter to produce recombinant DNA
43
explain the process of genetic engineering
1. The DNA that is going to be transferred is cut out with a restriction enzyme. The cut leaves one of the DNA strands with unpaired bases - this is called sticky ends 2. The SAME restriction enzyme is used to cut open the vector DNA. It could be a plasmid or a virus. 3. The vector DNA and the DNA you are inserting are left with complementary sticky ends . They are mixed together with ligase enzymes . 4. Ligase joins the sticky ends together to produce recombinant DNA 5. The recombinant DNA is inserted into other cells such as bacteria 6. The cells can now use the inserted gene to make the protein it codes
44
what do restriction enzymes do
recognise specific sequences of DNA and cut the DNA at these points
45
what is a vector
something used to transfer DNA into a cell
46
what are the benefits of genetic engineering
lots of medicines can be produced easily higher crop yields
47
what are the negatives of genetic engineering
we do not know what the effect modifying its genomes will have on the organism as some do not survive transplanted genes may get out into the environment genetically modified crops could adversely affect food chains or even human health
48
what are the benefits of genetically modifying plants
increase the yield of food crops can be engineered to contain additional nutrients which can help deficiency diseases
49
what are the disadvantages and concerns about genetically modifying crops
people are not hungry due to a lack of food, but because it is too expensive countries may become dependant on companies who sell GM seeds GM crops won't survive if there is poor soil concerns that the long term effects of exposure to GM crops on human health and environment are not yet known
50
what is Bt
a type of bacterium that produces a toxin that kills many of the insect larvae that are harmful to crops
51
what are the benefits of the Bt toxin
improved crop yield reduces need for chemical pesticides
52
risks of Bt crops
insects that feed on the crops will eventually become resistant farmers may still use pesticides
53
what are other methods of increasing food production
fertilisers biological control
54
what are the benefits of using fertilisers
they contain minerals which are essential for plant growth and replace nutrients lost from the soils to previous crops
55
what are the negatives of using fertilisers
cause eutrophication
56
what does biological control do
use other organisms to reduce pest numbers
57
what are the benefits of biological control
long lasting effects less harmful to wildlife cheaper
58
what are the negatives of biological control
new organisms can cause problems as they might become pests themselves

BIOLOGY (9 decks)

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