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Aqa Biology GCSE > y11 test4 > Flashcards

y11 test4 Flashcards

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1
Q

What is variation?

A

differences in the characteristics of individuals in a population

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2
Q

What is interpecific variation?

A

variation between species

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3
Q

What is intraspecific variation?

A

variation within species

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4
Q

What characteristics are caused by our genes?

A

blood group
eye colour
natural hair colour
earlobe shape

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5
Q

What characteristics are caused by the environment?

A

scars
tattoos
language
hair colour/length

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6
Q

What characteristics are cause by a combination of our genes and the environment?

A

mass
sporting achievements
height
skin colour

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7
Q

What 3 processes lead to genetic variation?

A

meiosis (random fertilisation & crossing over)
sexual reproduction
mutations

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8
Q

What is evolution?

A

a change in the inherited characteristics of a population over time through a process of natural selection

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9
Q

What was Jean Baptiste Lamarck’s theory about evolution?

A

Within a species, organisms all start off looking very similar. Some individuals change as a result of use/disuse of a body part, giving them an acquired characteristic. Their offspring then inherit their acquired characteristics and develop them further. Eventually, the environment will have directly affected individuals, changing the nature of the species

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10
Q

What 3 things are needed for evolution to take place?

A

variation, selection, time

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10
Q

What was Charles Darwin’s theory about evolution?

A

Within a species, there is always variation. A random, chance mutation occurs that alters the genotype and phenotype of some individuals. Those with the mutation have a survival advantage in that particular environment. Those individuals are more likely to survive, reproduce and pass on the gene for the desired characteristic. This is an inherited characteristic. Over time, the new phenotype becomes normal. This is called natural selection. Nature if effectively selecting the organism with the most useful genes

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10
Q

Why didn’t people believe Darwin straight away?

A

His views opposed the church

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10
Q

What does the theory of evolution state?

A

the species alive today have evolved from simple life forms that first developed more than 3 BILLION years ago

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10
Q

What were Darwin’s main observations?

A

1) overproduction of offspring
2) numbers within a population stayed constant
3) variation exists between offspring
4) struggle for survival
5) survival of the fittest

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10
Q

How can we prevent extinction?

A
  • education
  • reduce consumption
  • stricter pollution laws
  • increase renewable energy usage
  • eat less meat and dairy
  • captive breeding programs
  • reduction of climate change
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10
Q

What are some causes of extinction?

A
  • illegal wildlife trade
  • overfishing
  • climate change
  • pollution
  • destruction of natural habitats
  • population growth
  • overconsumption
  • predators
  • disease
10
Q

How does mineralisation occur?

A

1) An organism dies and sinks to the bottom of the water
2) The organism becomes covered in sediment, the soft parts of the body decay and the sediment begins to turn to rock
3) More sediment settles, more organisms die and the sediment is compressed as more layers are added
4) Minerals replace the bone and the skeleton turns to rock
5) Rock layers become lifted up, they are eroded by wind and rain and faults in the rock expose the fossils

10
Q

How do genetics show evidence of evolution?

A

An understanding of DNA means we can see mutation leading to a survival advantage, leading to evolution

10
Q

How does speciation show evidence of evolution?

A

At the end of speciation, evolution must have occurred as offspring from different species cannot reproduce to give fertile offspring

10
Q

What is Wallace’s warning colouration?

A

Use of bright colour to deter predators- predators learned to avoid animals with these colourations as they are likely to cause injury, taste bad or be poisonous. He realised warning colouration must be passed on by natural selection.

10
Q

How do fossils show evidence of evolution?

A
  • If two fossils are found in the same sediment layer we can assume they were alive at the same time
  • If there is no change between the fossils in different layers, we can see that the species was well adapted to their environment (which didn’t change) so there was no need for evolution
  • If a fossil disappears from a layer and all future layers, we can see when the animal went extinct
  • If each layer shows a slightly different species, it suggests the species evolved over time. It is likely that the environment changed and natural selection occurred, changing the overall phenotype of the species which we can see in fossils. We can compare their anatomy to see how they evolved over time (simple –> complex)
10
Q

What is a fossil?

A

the remains of an organism that lived millions of years ago

10
Q

What is a species?

A

a group of organisms which have similar characteristics and can successfully breed with each other to produce fertile offspring

10
Q

What did Wallace discover

A

warning colouration and speciation

10
Q

Name 5 ways that fossils are formed:

A

Mineralisation
Preserved in ice
Preserved in resin/sap (amber)
Volcanic ash
Traces of footprint buried under sediments

10
Q

Why is the fossil record incomplete?

A
  • not all specimens are in a suitable environment for fossilisation
  • fossils could have been destroyed by natural disasters/ urbanisation
  • not all of them may have been found
  • not identified as fossils
  • fossilisation process disrupted
  • soft bodied organisms can’t be fossilised, only preserved in amber
11
Q

Why are hybrids often infertile?

A

their chromosome number is odd. meiosis halves the chromosome number, so meiosis can’t successfully take place

12
Q

How does speciation occur?

A

1) A population becomes geographically isolated from the original population
2) The new population is exposed to different environmental conditions
3) Mutations may occur, creating variation in the new population, so there will be new phenotypes
4) Natural selection occurs whereby the best adapted individuals in the new population survive and reproduce. Others won’t survive
5) Over a long period of time, the new population changes to the point where it can no longer interbreed with the old population to give fertile offspring
6) Speciation has occurred

13
Q

When was the structure of DNA determined?

A

mid 20th century

Aqa Biology GCSE (8 decks)

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