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SHHS - Science - AQA Biology Trilogy > 4.6 evidence evolution, fossils, extinction, resistant bacteria > Flashcards

4.6 evidence evolution, fossils, extinction, resistant bacteria Flashcards

1
Q
  1. What is a fossil?
A

Remains of organisms from millions of years ago

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2
Q
  1. Where are fossils round?
A

Sedimentary rocks

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3
Q
  1. What evidence is provided by fossils?
A

How much or how little organisms have evolved over time

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4
Q
  1. Which parts of organisms do not easily decay?
A

Bones, teeth and shells

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5
Q
  1. What are mineral replacement fossils?
A

When hard parts of an organism are replaced by minerals as they slowly decay

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6
Q
  1. What is a cast or impression fossil?
A

when soft material surrounding a dead and buried organism harden around it leaving a cast

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7
Q
  1. What are trace fossils?
A

Burrows, footprints or root traces which have become a cast or impression fossil, rather than a fossil of the organism itself

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8
Q
  1. What three factors are needed for decay to occur?
A

Oxygen, water and a suitable temperature

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9
Q
  1. In which conditions may decay be prevented, hence preserving a dead organism?
A

In amber, tar bogs, ice or peat bogs

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10
Q
  1. Why can we not be 100% sure of how life on Earth began?
A

No one was there to witness the event, and evidence is lacking

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11
Q
  1. There are various suggestions for how life came to be on Earth. Describe one.
A

Live cells were brought on comets from elsewhere. Life began in the primordial swamp or under the sea.

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12
Q
  1. Why is fossilisation a rare event?
A

Early life forms were soft bodied so did not form fossils as they decayed easily, and fossils are destroyed over time by geological activity

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13
Q
  1. What sort of geological activity destroys fossils?
A

Movement of tectonic plates

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14
Q
  1. Whose theory of evolution was Natural Selection?
A

Charles Darwin

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15
Q
  1. The fact that resources are limited means that all organisms have to _________ for survival.
A

Compete

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16
Q
  1. What are the key words needed to explain Natural Selection ?
A

Mutation, Variation, Advantage, Survive, Reproduce, Genes (My Very Angry Sisters Rat Growls).
e.g. A DNA mutation leads to variation n the population of an organism. The individuals with an advantage are move likely to survive, reproduce and pass on genes to offspring.

17
Q
  1. What did Darwin’s theory not explain?
A

How characteristics are passed on from parents to offspring, and how new characteristics appear.

18
Q
  1. What provides evidence for evolution?
A

Fossils, DNA evidence, mechanism of inheritance, bacterial resistance to antibiotics.

19
Q
  1. What is the development of new species called?
A

Speciation.

20
Q
  1. What must happen to a group of organisms for them to become different species?
A

Reproductively isolated so cannot interbreed.

21
Q
  1. Define the term ‘species’.
A

Member of the same species can interbreed and produce fertile offspring.

22
Q
  1. What might cause a species to become extinct?
A
  • When the environment changes too quickly (e.f.habitat destruction).
  • killed by a new predator.
  • Out competed by a new competitor.
  • Killed by a new disease.
  • Killed by a catastrophic event (volcanic eruption, asteroid hit)
23
Q
  1. What drug is given to cure bacterial infections?
A

Antibiotics.

24
Q
  1. What are random changes in the DNA called?
A

Mutations.

25
Q
  1. Populations of resistant strains of bacteria increase more than non-resistant strains. Why?
A

The resistant strains have an advantage over the non-resistant strains so they survive, reproduce and pass on genes more easily. This is an example of Natural Selection.

26
Q
  1. Why do Bacteria evolve more quickly than most other organisms?
A

They reproduce quickly by asexual reproduction.

27
Q
  1. What name is given to bacterial infections which are resistant to many antibiotics?
A

Superbugs.

28
Q
  1. Give an example of a superbug.
A

MRSA

29
Q
  1. Why is antibiotic resistance in bacteria a growing problem?
A
  • Over-prescribed by GP’s
  • Inappropriately prescribed when not needed (for viruses)
  • Patients do not complete the course leaving the most resistant bacterial cells to reproduce.
  • Overuse in agriculture resulting in animal diseases which can spread to humans.
30
Q
  1. Does the antibiotic cause the bacterial cells to mutate and become resistant?
A

No. Antibiotics kill off the non-resistant strains more easily leaving the resistant strains which have the advantage to survive and reproduce.

31
Q
  1. Why can we not keep up with resistant bacteria?
A

Production of new antibiotics is slow and costly.

SHHS - Science - AQA Biology Trilogy (37 decks)

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