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Biology Yr 10-11 > Unit 18 > Flashcards

Unit 18 Flashcards

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1
Q

what is variation

A

the differences between individuals of the same species

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2
Q

result of continuous variation

A

when theres a range of phenotypes between two extremes

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3
Q

result of discontinuous variation

A

a limited number of phenotypes with no intermediates(blood groups etc)

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4
Q

what is discontinuous variation usually caused by

A

genes

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5
Q

what is continuous variation usually caused by

A

by both genes and environment

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6
Q

what is continuous variation

A

when there are small degrees of differences for a particular characteristic between individuals

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7
Q

what is discontinuous variation

A

when there are distinct differences for a characteristic with no ‘inbetweens’

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8
Q

what does the graph of continuous variation look like

A

smooth curves

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9
Q

what does the graph of discontinuous variation look like

A

blocks, step like shapes

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10
Q

what is phenotypic variation

A

when the variation is caused by genetics or environment

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11
Q

what is genetic variation

A

when the variation is completely controlled by genes

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12
Q

what is mutation

A

genetic changes

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13
Q

what is the result of mutation

A

occasionally new alleles are formed

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14
Q

what is gene mutation

A

the random change in the base sequence of DNA

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15
Q

what increases the chance/rate of mutation

A

ionising radiation(gamma and Xrays)
certain types of chemicals

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16
Q

what are the sources of genetic variation in populations

A

mutation,meiosis,random mating and random fertilization

17
Q

what are adaptive features

A

an inherited feature that helps an organism to survive and reproduce in its environment

18
Q

what is fitness

A

the probability of an organism surviving and reproducing in the environment in which it is found

19
Q

what are hydrophytes

A

plants adapted to live in extremely wet conditions

20
Q

what are the adaptations of hydrophytes

A

large air spaces in the leaves- keep them close to the surface of the water for more photosynthesis
small roots- they can extract nutrients from the surrounding water
stomata usually open all the time and found on the upper epidermis

21
Q

what are xerophytes

A

they are plants adapted to live in extremely dry conditions

22
Q

common adaptations of xerophytes

A

thick waxy cuticle- cuts down water loss
sunken stomata- reduces evaporation rate
small leaves-many have small needle shaped leaves
extensive shallow roots
thickened leaves or stems

23
Q

what is natural selection

A

the individuals that have the best adaptive features are the ones most likely to survive and reproduce

24
Q

why is there a ‘struggle for survival’ in many environments

A

many organisms produce more offspring than the environment is able to support which leads to competition for foods and other resources

25
Q

what is survival of the fittest

A

individuals with characteristics most suited to the environment have a higher chance of survival and reproduction. These characteristics are then passed down to their offspring
leads to a greater number of individuals with the better adapted variations

26
Q

what is adaptation

A

the process,resulting from natural selection, by which populations become more suited to their environment over many generations

27
Q

how is the development of antibiotic resistant bacteria an example of natural selection

A

the bacteria that possess the characteristics that make it resistant to antibiotics reproduce and pass it on the next generation

28
Q

what is selective breeding

A

to select individuals with desirable characteristics and breed them together

29
Q

outline the process of selective breeding

A

the offspring with desirable characteristics are bred together again and again until their offspring reliably show the selected characteristics

30
Q

differences between natural selection and artificial selection

A

artificial selection only occurs when humans intervene
in natural, the features are better adapted for survival
in artificial, the features are useful to humans
natural takes a long time to occur
artificial takes a shorter amount of time

Biology Yr 10-11 (20 decks)

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