B14- evolution 🦕 Flashcards

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1
Q

What are fossils ?

Hint: found in

A
  • fossils are the remains of organisms from millions of years ago, which are found in rocks
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2
Q

Name the three ways fossils can form

Hint: absent

A
  • fossils can form from parts of organisms that have not decayed, because one or more of the conditions needed for decay are absent
  • fossils may form, when parts of organisms are [slowly] replaced by minerals as they decay
  • and, fossils may form as preserved traces of organisms such as: footprints, burrows and rootlet traces [preserved spaces where roots where]
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3
Q

Why might decay be absent ?

Hint: water

A
  • the temperature may be too cold
  • there may not be enough oxygen
  • and, there may not be enough water
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4
Q

Why can’t scientists be certain about how life began on Earth ?

A
  • many early forms of life were soft-bodied organisms [didn’t have a shell or skeleton], which means they left few traces [few fossils] behind
  • and most of the few traces that did form as fossils, have mainly been destroyed by geological activity, as there are changes to rocks in the Earth’s crust
  • [so as there are very few fossils of the early forms of life, scientists cannot be certain about how life on Earth began]
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5
Q

What does it mean for a species to be ‘extinct’ ?

Hint: remaining

A
  • a species is extinct, when there are no remaining individuals of that species still alive
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6
Q

Name the three factors that may contribute to the extinction of a species

A
  • species can become extinct due to a catastrophic event [such as an asteroid colliding with the Earth, which eventually lead to the extinction of the dinosaurs]
  • a species can become extinct if the environment changes [e.g- changes to weather patterns]
  • and, a species can become extinct due to a new disease or a new predator, which kills all of the individuals of a species
  • and a species can also become extinct, if a new more successful species evolves and competes with it [due to scare food or scare water]
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7
Q

Why do bacteria evolve rapidly ?

A
  • bacteria evolve rapidly because, they reproduce at a fast rate
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8
Q

What are antibiotics used in ?

A
  • antibiotics are widely used in medicine- to treat bacterial diseases
  • antibiotics are also used in farming
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9
Q

Why are antibiotics used in farming ? 🐖

A
  • antibiotics are used in farming, to prevent animals from developing bacterial diseases
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10
Q

How does antibiotic resistance happen ?

A
  • a colony of bacteria have mutations of bacterial pathogens, which produce new strains
  • some of these strains are resistant to antibiotics, so these strains survive and are not killed.
  • these strains of bacteria now reproduce, so the population of the resistant strain rises.
  • the resistant strain then spreads because, people are not immune to it and there is no effective treatment
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11
Q

What is the first step of antibiotic resistance ?

A
  • a colony of bacteria have mutations of bacterial pathogens, which produce new strains
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12
Q

In antibiotic resistance, what happens to the new strains from mutations ?

A
  • some of these strains are resistant to antibiotics, so these strains survive and are not killed.
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13
Q

What happens to the resistant strain of bacteria, that are not killed ?

A
  • these strains of bacteria now reproduce [without any competition from other bacteria] so the population of the resistant strain rises.
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14
Q

What happens after the population of the resistant strain of bacteria rises ?

A
  • the resistant strain then spreads because, people are not immune to it and there is no effective treatment
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15
Q

How can the rate of development of antibiotic resistant strains of bacteria, being reduced ?

A
  • doctors should not prescribe antibiotics inappropriately [e.g- to treat viral infections, as antibiotics only kill bacteria]
  • patients should complete their course of antibiotics, so all bacteria are killed and none survive to mutate and form resistant strains
  • and, the agricultural use of antibiotics should be restricted [to prevent the spread of antibiotic resistance from animal to human pathogens]
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16
Q

Why can’t researchers keep up with the emergence of new antibiotic resistant strains ?

A
  • the development of new antibiotics is costly and slow, which means it is unlikely to keep up with the emergence of new resistant strains
17
Q

Who classified species into different categories, based on their structure and characteristics ?

A
  • In the 1800s, the biologist Carl Linnaeus classified species into different categories, based on their structure and characteristics
18
Q

How were living things originally classified ?

A
  • living things were originally classified [by Carl Linnaeus] into: kingdom, phylum, class, order, family, genus and species
  • [remember the mnemonic: kids prefer cheese over fried green spinach]
19
Q

What two kingdoms were all living things originally divided into ?

A
  • Carl Linnaeus divided all living organisms into two kingdoms: plant and animal kingdoms
  • and he then divided each kingdom into smaller categories, which is known as his classification system
20
Q

How are organisms named ?

A
  • organisms are named by the binomial [two names] system of genus and species
  • [this means a species first name will be its genus, and its second name will be its species]
21
Q

Why have new models of classification be proposed ?

A
  • new models of classification have been proposed because:
  • internal structures have become developed due to an improvement in microscopes.
  • and the understanding of biochemical processes have progressed [as an organisms’ DNA can be analysed]
22
Q

What is the three domain system ?

A
  • the three domain system, is a new classification system developed by Carl Woese, who compared the biochemistry of different organisms
  • Carl Woese, divided organisms into: archaea, bacteria and eukaryota
23
Q

In the three domain system, what are archaea ?

A
  • archaea, are primitive bacteria typically living in extreme conditions [such as hot springs and salt lakes]
24
Q

In the three domain system, what are bacteria ?

A
  • the bacteria domain contains ‘true bacteria’, such as E.coli and they can live in the human digestive system
  • true bacteria look similar to archaea [primitive bacteria]; there are multiple biochemical differences between them
25
Q

In the three domain system, what are eukaryota ?

A
  • the eukaryota domain includes protists [e.g- amoeba], fungi, plants and animals.
26
Q

What are evolutionary trees ?

A
  • evolutionary trees are a method used by scientists, to show how closely related organisms are to each other
27
Q

How are evolutionary trees made ?

A
  • to make an evolutionary tree, scientists can use their classification data on living organisms [e.g- DNA]
  • ; for extinct organisms, scientists have to use fossils, which present a promblem
28
Q

When making evolutionary trees, why are using fossils a promblem ?

A
  • the fossil records of many species are incomplete because, there are very few fossils of the early forms of life