Topic 18 Flashcards

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1
Q

What is variation?

A

The difference between organisms of the same species

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2
Q

What is discontinuous variation?

A

Variation that produces distinct categories (e.g. eye colour or blood groups

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3
Q

What is continuous variation?

A

Variation that cannot be placed into distinct categories and instead produces a spectrum (e.g. height, weight)

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4
Q

What is a mutation?

A

A random change in the base sequence of the DNA of an organism

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5
Q

State 2 things which may increase the rate of mutation

A

-Ionising radiation (x-rays / uv)
-Certain chemicals (mutagens & carciogens)

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6
Q

Other than mutations, what else can give rise to variation?

A

Random fertilisation, meiosis, random mating

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7
Q

What is an adaptive feature?

A

The inherited functional features of an organism that help it survive in its environment

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8
Q

What are hydrophytes?

A

Plants which are adapted to live in aquatic conditions

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9
Q

State 3 adaptations of hydrophytes

A

Wide and flat leaves/ Thin waxy cuticle
Stomata on only upper surface (maximise gas exchange)
Flexible stems (not damaged by currents)
Air spaces (float = more light exposure

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10
Q

What are xerophytes?

A

Plants which are adapted to live in very arid and dry conditions

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11
Q

State 3 adaptations of xerophytes

A

Rolled leaves (trap humid air)
Thick waxy cuticle (less water loss by evaporation)
Small needle shaped leaves
Fewer stomata + in sunken pits surrounded by hair (slows transpiration down)

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12
Q

Describe the process of natural selection

A

“Populations are naturally varied due to random genetic mutations
Some of these mutations provide a selective advantage
These organisms survive and reproduce, passing on the successful genes”

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13
Q

Define evolution

A

A change in the features of organisms over time due to natural selection

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14
Q

What is the process of adaptation?

A

Populations become more suited to their environment over time due to natural selection

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15
Q

What is the development of antibiotic resistance an example of?

A

Evolution by natural selection

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16
Q

Describe how antibiotic resistance arises

A

“A random genetic mutation causes a bacterium to become resistant to the antibiotic
When the antibiotic is used, all the bacteria that do not have the mutation are killed
The population containing just the resistant bacteria then begins to grow”

17
Q

Describe how selective breeding is carried out

A

“Organisms with the desired traits are selected
These organisms are bred together
This process is repeated until the offspring have the desired characteristics”

18
Q

What is the difference between natural selection and artificial selection?

A

Natural selection occurs when the selection pressures are created by the environment whereas artificial selection is when humans deliberately create selection pressures