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LGS Biology > B5.2 Natural Selection and Evolution > Flashcards

B5.2 Natural Selection and Evolution Flashcards

1
Q

Evidence that shows change has taken place

A
  1. Fossil record
  2. Rapid changes in species
  3. Genetics
  4. Extinction
  5. Molecular comparison
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2
Q

What does the evidence for fossils provide us?

A

A history of past life in earth.

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3
Q

Why are fossils a significant source of evidence?

A
  • They show evolution within a species and evolution between one group of organisms
  • They can help to build a comprehensive history
  • They allow a picture to be built in terms of life upon Earth e.g. earliest fossils bacteria, then plants, then animal fossils.
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4
Q

How does fossil evidence show evolution has occurred?

A
  • Systematic change through time
  • Different fossils found in different rock
  • Oldest layers of rock show oldest fossils
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5
Q

What can be seen in the fossil record?

A
  • increase in complexity over time, simple organisms appeared first
  • increase in diversity
  • intermediate forms between groups - transitional fossils
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6
Q

What can not be seen in the fossil record?

A
  • Unable to show how life started on earth
  • Earliest fossils were soft bodied, difficult to fossilise
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7
Q

Does evidence from fossils provide conclusive proof of change?

A
  • No. Record is biased/incomplete
  • Very few individuals become fossils
  • Hard-bodied organisms often form fossils
  • Most fossils are aquatic animals
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8
Q

What are the main fossil types found?

A
  • Impressions are formed when footprints become covered in mud which hardens to rock.
  • Moulds are formed when a dead organism gets buried in mud, which hardens to rock.
  • Caste fossil can occur when mould fossils are filled with minerals that harden, taking the shape of the mould fossil
  • Preserved fossils occur when animals have been covered in a natural preservative such as ice, tar, amber or peat
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9
Q

How does extinction provide evidence for evolution by natural selection?

A

Species which are not adapted to / do not have advantageous characteristics for their environment die out.

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10
Q

State what is meant by the term fossil.

A

The remains of a plant or animal which have mineralised / changed to rock over millions of years

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11
Q

State the most likely ancestor of all living things?

A

Unicellular aquatic organisms

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12
Q

How do organisms evovle?

A

Through the process of natural selection.

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13
Q

What is the process of evolution by natural selection?

A
  • Genetic variation is seen within species caused by differences in genes
  • Organisms which have the most advantageous characteristics are the most likely to survive and reproduce
  • Genes from successful organisms are passed to offspring
  • This process is repeated many times and can lead to new species developing.
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14
Q

What is meant be the term ‘survival of the fittest’?

A

Only the organisms which have the most advantageous characteristics are the most likely to survive.

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15
Q

Why must scientist constantly develop new antibiotics?

A

Bacteria reproduce quickly, so any mutation which develops antibiotic resistance is quickly passed on to many offspring.

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16
Q

State two examples of evolution that has happened in a short and observable time period?

A
  • The peppered moth changing from pale to dark due to the industrial revolution
  • Bacteria evolving resistance to antibiotics
  • Mosquitos evolving resistance to DDT
  • Rats evolving resistance to the rat poison warfarin
17
Q

During Darwin’s infamous scientific expedition to the Galapagos Island, on which species did he make his famous observations?

A

Finches

18
Q

Who’s hypothesis about the origins of fossils gave Darwin inspiration for the theory of evolution by natural selection?

A

Charles Lyell’s

19
Q

What was the theory of spontaneous generation?

A

Appearance of animals from environments previously devoid of animals e.g. sudden appearance of fish in a puddle of water.

20
Q

State the key ideas of Jean-Baptiste Lamarck.

A
  • All organisms evolved through simple to more complex organisms
  • Use vs. Disuse
  • Organisms adapt during their lifetime - altered their behaviour in response to environmental change, which modifies their organs.
  • Acquired traits are heritable - when giraffes stretch their necks to reach leaves high in trees, they would strengthen and gradually lengthen their necks. These giraffes would then have offspring with slightly longer necks.
  • Continuous evolution towards ‘perfection’
21
Q

This scientist independently proposed the theory of evolution by natural selection while working in Borneo.

A

Alfred Wallace (1809-1882)

22
Q

What where Alfred Wallace’s key ideas?

A
  • Living things change over long periods of time
  • Fittest individuals survived and reproduced
  • Advantageous characteristics passed on to their offspring
  • Speciation by reproductive isolation – Wallace effect
23
Q

The study of which species led to Wallace’s thinking?

A

Beetles and butterflies

24
Q

Why did the theory of evolution take time to be widely accepted?

A
  • At the time of publication, most people believed God created all animals and plants.
  • Darwin’s theory was new / opposed this belief.
  • Darwin was unable to explain how inheritance occurred
  • Darwin had no knowledge of genes, which meant it was hard to convince people that the theory was correct.
  • It took time to collect further evidence to support the theory.
25
Q

Name the three key scientists who provided evidence for the theory of evolution.

A

Charles Lyell

Charles Darwin

Alfred Wallace

26
Q

What is classification?

A

The organisation of living things into groups according to their similarities in genes, structure and characteristics

27
Q

What is the Linnaean classification system?

A
  • Classification is the organisation of living things into groups according to their similarities in structure and characteristics
  • Closely related organisms are grouped together into groups called ‘taxa’
  • Each taxa is arranged in a hierarchy, which divide into smaller more specific taxa.
  • Kingdom - Phylum - Class - Order - Family - Genus - Species
28
Q

What is phylogeny and how has it advanced classification?

A
  • Study of evolutionary relationships with the aid of modern techniques such as DNA and protein analysis.
  • It has led to the re-classification of some organisms
  • It has led to the devlopment of the 3-domain system and the new taxon ‘domain’
29
Q

What is the 3-domain system?

A
  • Proposed by Carl Woese
  • Classifies based upon chemical analysis - DNA, RNA and protein comparison to show phylogenic links
  • Three domains:
    1. Eukaryota – organism with complex subcellular structures (animals, plants, fungi, protist)
    2. Bacteria – true bacteria
    3. Archaea – primitive bacteria
30
Q

What was artificial classification?

A
  • Grouping by observable characteristics not phylogeny
  • Method led to inaccurate classification.
  • Linnaeus’s method of classifying plants based on a limited number of their physical and sexual characteristics.

LGS Biology (21 decks)

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