4.6 evidence evolution, fossils, extinction, resistant bacteria Flashcards Preview

11B1 - AQA Biology Trilogy > 4.6 evidence evolution, fossils, extinction, resistant bacteria > Flashcards

Flashcards in 4.6 evidence evolution, fossils, extinction, resistant bacteria Deck (31)
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1. What is a fossil?

Remains of organisms from millions of years ago

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2. Where are fossils round?

Sedimentary rocks

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3. What evidence is provided by fossils?

How much or how little organisms have evolved over time

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4. Which parts of organisms do not easily decay?

Bones, teeth and shells

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5. What are mineral replacement fossils?

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

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6. What is a cast or impression fossil?

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

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7. What are trace fossils?

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. What three factors are needed for decay to occur?

Oxygen, water and a suitable temperature

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

In amber, tar bogs, ice or peat bogs

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

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

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

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

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12. Why is fossilisation a rare event?

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. What sort of geological activity destroys fossils?

Movement of tectonic plates

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14. Whose theory of evolution was Natural Selection?

Charles Darwin

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

Compete

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

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.

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17. What did Darwin's theory not explain?

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

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18. What provides evidence for evolution?

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

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19. What is the development of new species called?

Speciation.

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

Reproductively isolated so cannot interbreed.

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21. Define the term 'species'.

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

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22. What might cause a species to become extinct?

- 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)

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23. What drug is given to cure bacterial infections?

Antibiotics.

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24. What are random changes in the DNA called?

Mutations.

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

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.

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

They reproduce quickly by asexual reproduction.

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

Superbugs.

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28. Give an example of a superbug.

MRSA

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29. Why is antibiotic resistance in bacteria a growing problem?

- 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.

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30. Does the antibiotic cause the bacterial cells to mutate and become resistant?

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