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BIOLOGY > SB4: natural selection & genetic modification > Flashcards

SB4: natural selection & genetic modification Flashcards

1
Q

who made the theory of evolution?

A

darwin & wallace

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2
Q

what was darwin’s theory?

A

(survival of the fittest/natural selection)
-individuals with characteristics most suited to the environment are more likely to survive and to breed successfully
-the characteristics that have enabled the to survive are then passed on to the next environment

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3
Q

what is natural selection?

A

the species that is more adapted to surviving in its environment will survive the longest and pass on it’s genes

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4
Q

steps of natural selection

A
  1. an individual of a species shows genetic variation
  2. there is a random environmental change and competition happens
  3. better adapted individuals survive
  4. survivors pass on their better genes, generations later there will only have the genetics of the original suvivors
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5
Q

what are antibiotics?

A

chemicals produced by bacteria and fungi that inhibit or kill other microbes

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6
Q

natural selection shown through antibiotics

A
  1. random mutation happens in bacteria, nothing happens until antibiotics are used
  2. antibiotics are introduced and the mutated bacteria becomes resistant
  3. while the other bacteria dies, a point is reached where only resistant bacteria remains and they reproduce, all the population consists of the resistant bacteria
  4. the immune system is left to deal with these bacteria as they can’t be killed through antibiotics
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7
Q

evolution

A

the gradual change in a species over time so that they can become more suited to an environment

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8
Q

humans

A

homo sapiens

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9
Q

what is a fossil?

A

the preserved remains of a dead organism from millions of years ago

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10
Q

when do fossils form?

A

-when hard body parts, such as bones and shells, which do not decay easily or are replaced by minerals as they decay

-when parts of organisms that have not decayed because one or more of the conditions needed for decay are absent

-preserved traces of organisms become covered by layers of sediment, which eventually become rock

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11
Q

what is the problem with fossils?

A

-few organisms form fossils
-there are gaps in fossil records
-there may be minimal DNA
-fossils may get damaged

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12
Q

how can you tell the time that tools were from?

A

carbon dating

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13
Q

pentdactyl limb

A

similar structure suggests that many vertebrates descended from the same common ancestor

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14
Q

ancestors of humans…

A

hominins

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15
Q

ardi (ardipithecus ramidus)

A

-4.4 million ears old
-skull = 350cm³
-big toes stuck out for climbing

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16
Q

australopithecus afarensis (lucy)

A

-4.3 million years ago
-skull size: 400cm³
-probably walked upright
-toes arranged like humans

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17
Q

homo habilis

A

-first to make stone tools
-2.5-1.5 million years ago
-leakey’s
-skull size: 500 - 600cm³
-walked upright, short, long arms

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18
Q

homo erectus

A

-2-0.5 million years ago
-leakeys’s
-850 cm³ = skull size
-1.79m, strong build

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19
Q

homo sapiens

A

195,500 years
-skull size: 1450cm³
-upright walking

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20
Q

classification

A

the process of grouping things based on their similarities

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21
Q

what does classification do?

A

-make things easier to study
-helps us understand how living things are related
-allows us to make sense of the living world
-gives us a sense of the living world

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22
Q

binomial system

A

identifying organisms by their genus and species names (eg: homo sapien)

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23
Q

linnean classification

A

kingdom
phylum
class
order
family
genus
species

24
Q

kingdom

A

animals
(multicellular, nuclei, no cell walls)

plants
(multicellular, chloroplasts, nuclei, cellulose cell walls)

fungi
(multicellular, live in/ on dead, nuclei, chitin in cell walls)

prokaryotes
(unicellular, no nuclei, flexible cell walls)

protists
(unicellular, nuclei, some have cell walls)

25
Q

breeds vs varieties

A

breeds = new animals
varieties = new plants

26
Q

selective breeding (artificial selection)

A

when humans breed plants and animals for particular genetic characteristics

27
Q

inbreeding

A

when plants or animals are bred within a small gene pool

28
Q

what can inbreeding lead to?

A

inherited disease or defects

29
Q

selective breeding steps

A
  1. decide which characteristics are important enough to select
  2. choose parents that show these characteristics
  3. choose the best offspring from parents to produce the next generation
  4. repeat the process until all offspring show desired characteristics
30
Q

advantages of selective breeding

A

-animals can be made that can’t cause harm
-more food or better quality food
-higher yield of food

31
Q

disadvantages of selective breeding

A

-reduced gene pool
-inbreeding
-rare diseases could be unknowingly selected as part of positive trait
-reduced genetic variation can lead to attack by specific insects or disease, which could be extremely destructive

32
Q

desired characteristics in plants:

A

-disease resistance in food crops
-wheat plants that produce lots of grain
-large or unusual flowers

33
Q

desired characteristics in animals

A

-animals that produce lots of milk or meat
-chickens that lay large eggs
-domestic dogs that have a gentle nature

34
Q

how can you show if two animals are from the same species?

A

-breed them and their offspring should be fertile

35
Q

clones

A

genetically identical individuals

36
Q

what’s the simplest way to clone a plant?

A

taking a cutting

37
Q

steps of cutting cloning

A
  1. branch from the parent plant is cut off, its lower leaves are removed, and the stem is planted in damp compost
  2. plant hormones are often used to encourage new roots to develop
  3. the cutting is usually covered in a clear plastic bag to keep it moist and warm
  4. after a few weeks, new roots develop and a new plant grow
38
Q

what is tissue culture?

A

-the growing of cells or tissues in liquid containing nutrients/ on a solid medium (nutrient agar) to create identical cells
-they may form a callus (a clump of undifferentiated cells) and then get treated to make them differentiate and become specialised

39
Q

why is everything in tissue culture sterilised?

A

to remove the pathogens so that the plants growth isn’t prohibited

40
Q

how can tissue culture be used medically?

A

for transplants

41
Q

what are the advantages of tissue culture?

A

-faster than vegetative reproduction
-can breed desirable traits
-not dependant of seasons
-extinct/endangered things can be brought back

42
Q

disadvantages of tissue culture

A

-more labour and money used
-process not guaranteed success

43
Q

genetic engineering

A

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

44
Q

vectors

A

carry and transmit disease

45
Q

process of cloning animals

A
  1. the nucleus is removed from an unfertilised egg cell
  2. the nucleus from an adult body cell, such as a skin cell, is inserted into the egg cell
  3. an electric shock stimulates the egg cell to divide to form an embryo
  4. these embryo cells contain the same genetic information as the adult skin cell
  5. when the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development
46
Q

how is genetic engineering used?

A
  • medicine (inherited disease
    -agriculture (increasing yield)
    -bacteria producing insulin
47
Q

steps of genetic engineering/ modification

A
  1. restriction enzymes are used to isolate the required gene leaving it with sticky ends/unpaired bases
  2. a plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends
  3. the plasmid and the isolated gene are joined together by ligase enzyme.
    the vector inserts the gene into required cells.
  4. the genes are transferred to animal, plant or microorganism cells, during early development, which allows them to develop with the desired characteristics
48
Q

yield

A

amount of something that is produced

49
Q

bt toxin facts

A

-natural insecticide discovered in soil bacteria (1900)
-genes that produce this toxin were introduced to plants
-only affect insects that chew the plant tissues to pests that suck sap are left out and insecticides are still needed
-insects can develop resistance
-new versions of GM can be made to replace versions that pests are resistant to

50
Q

GM crops advantages and disadvantages

A

advantages:
-more yield
-less presticides = less costs
-more profit

disadvantages:
-cost of production

51
Q

advantages of pesticides

A

-very effective
-easy to apply
-can be used with almost all crops
-Used to get more profit

52
Q

disadvantages of pesticides

A

-reduces biodiversity
-expensive
-increased pesticide resistance
-toxic
-may kill important & innocent animals

53
Q

what are fertilisers?

A

chemicals added to soil to provide the nutrients needed for plant growth that was removed from ground after continuous plant growing

54
Q

disadvantages of fertilisers

A

-eutrophication
-kill animals

55
Q

biological control: advantages

A

-remove pests naturally
-non-toxic
-cheap
-long-term solution
-Usually highly specific to pest

56
Q

biological control: disadvantages

A

-expensive to find
-takes long
-introduced non-indigenous species
-doesn’t remove 100% of species

BIOLOGY (9 decks)

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