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SHHS - Science - AQA Biology Trilogy > 4.6 Variation and Evolution > Flashcards

4.6 Variation and Evolution Flashcards

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1
Q

What is a species?

A
  • Organisms that have similar features.

- And can breed to produce fertile offspring.

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2
Q

What is meant by a characteristic?

A

A feature of an organism e.g. hair colour, eye colour etc.

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3
Q

What is meant by ‘variation’?

A

Differences in characteristics between organisms.

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4
Q

The two types of variation are…

A
  1. Genetic variation

2. Environmental variation

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5
Q

Genetic variation is caused by..

A

The different genes that are inherited from parents.

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6
Q

Give examples of characteristics that are controlled ONLY by genes,

A

Natural eye colour
Blood type
Genetic diseases
Gender

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7
Q

How are genes passed on from parents to offspring?

A

Through gametes (eggs and sperm).

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8
Q

Do identical twins show genetic variation? Why?

A

No - because they inherit the sae genes from their parents.

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9
Q

Environmental variation is caused by…

A

The conditions of the environment that the organism is in e.g. light intensity, food availability

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10
Q

True or False - Most characteristics e.g. skin colour, height etc. are due to genes AND the environment.

A

TRUE

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11
Q

How can a mutation lead to variation?

A
  1. DNA base sequences change.
  2. This leads to a change in the protein a gene codes for.
  3. This changes an organisms phenotype.
  4. This could alter characteristics slightly.
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12
Q

Do characteristics that are caused by only genes show continuous or discontinuous variation?

A

Discontinuous - because there are only a few specific characteristics e.g. blue, brown, green eyes.

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13
Q

Do characteristics that are caused by only the environment show continuous or discontinuous variation?

A

Continuous - because there is a whole range of possible values e.g. height can vary immensely.

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14
Q

Whose theory explains the process of evolution?

A

Charles Darwin

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15
Q

What did Darwin use to help him come up with his theory of how evolution happens?

A
  1. Observations from a round the world trip.
  2. Experimental data
  3. Discussions with other scientists.
  4. Knowledge about fossils and geology.
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16
Q

What did Darwin call his theory of how evolution happens?

A

The theory of ‘Natural Selection’.

17
Q

The idea of the most well adapted organism outcompeting less well adapted organisms to survive and pass on their genes is sometimes called…

A

survival of the fittest.

18
Q

Explain how the process of natural selection leads to an organism evolving.

A 
RANDOM MUTATIONS lead to...
VARIATION in a population.
Some individuals have an ADVANTAGE...
So will SURVIVE and REPRODUCE and..
Pass on GENES.
Over time the population will have the advantageous characteristics.
19
Q

How old is the Earth?

A

4.5 Billion years

20
Q

How old is the Earth?

A

4.5 Billion years

21
Q

What is the order of words that must be used when answering a 6 mark Q on how natural selection leads to evolution?

A
  1. Random Mutation (Red Monkeys)
  2. Variation (Violently)
  3. Advantage (Attack)
  4. Survive (Smelly)
  5. Reproduce (Red)
  6. Genes (Gorillas)
22
Q

The characteristics that are expressed by an organism as a result of its genes are called its…

A

phenotype

23
Q

What is meant by extinction?

A

When no individuals of a species remain alive.

24
Q

List 5 causes of extinction.

A
  1. The environment changes too fast (habitat destroyed)
  2. A new predator kills them all.
  3. A new disease kills them all.
  4. They are out competed for food by a new species.
  5. A catastrophic event e.g. asteroid impact)
25
Q

When did Darwin publish his book ‘On the Origin of Species’?

A

1859

26
Q

Why was Darwin’s theory not immediately accepted by people?

A
  1. It went against religious believes.
  2. Darwin had no knowledge of genes or DNA because they had not been discovered.
  3. There was not much evidence.
27
Q

Who else came up with a scientific hypothesis about evolution happens?

A

Jean-Baptiste Lamarck

28
Q

Explain how Lamarck believed that evolution happens.

A
  1. An organism uses a characteristic a lot e.g. legs for running.
  2. The characteristic develops from being used e.g. legs get longer.
  3. The organisms offspring would acquire the changed characteristic.
29
Q

What is a hypothesis?

A

A possible explanation to explain an observation e.g. Darwin and Lamarck both came up with different hypotheses to explain why organisms appeared to change over time.

30
Q

Why might scientists develop different hypotheses to explain things that they observe?

A
  1. Different religious beliefs.

2. They are influenced by different people.

31
Q

If a hypothesis has enough evidence to support it it becomes accepted and is called a…

A

theory e.g. the theory of evolution by natural selection

SHHS - Science - AQA Biology Trilogy (37 decks)

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