Unit 4 - Variation and Evolution Flashcards

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1
Q

Give 4 sources of evidence for evolution

A

-Palaeontology (fossils)
-comparative anatomy
-comparative biochemistry
-comparative embryology

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2
Q

How can the relative age of fossils be determined?

A

-over time sediment is deposited to form rock strata
-recent rock strata are found at the top and older rock strata are found at the bottom
-radioisotope dating can be completed on fossils to date rock strata

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3
Q

How do fossils provide evidence for evolution?

A

-fossils of the simplest organisms are found in the oldest rocks
-fossils of more complex organisms are found in more recent rocks
-allow relationships between extinct and living organisms to be investigated
-sequence in which organisms are found matches ecological links

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4
Q

What is comparative anatomy?

A

The study of similarities and differences between organisms’ anatomy

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5
Q

What are homologous structures?

A

A structure which appears superficially different (and may perform different functions) in different organisms but has the same underlying structure

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6
Q

What is divergent evolution?

A

Species diverge over time into two different species, resulting in new species becoming less like the old one

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7
Q

What is comparative biochemistry?

A

Similarities and differences between the chemical make up of organisms

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8
Q

How does comparative embryology provide evidence for evolution?

A

-embryos of different animals looks very similar
-shows animals develop in a similar way
-implies the process of embryonic development has a common origin

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9
Q

Define interspecific variation

A

Differences between different species

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10
Q

Define adaptation

A

Characteristics that increase an organism’s chance of survival and reproduction in its environment

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11
Q

What are the 3 types of adaptations?

A

-structural
-behavioural
-physiological

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12
Q

What are physiological adaptations?

A

Adaptations relating to processes that take place within an organism

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13
Q

Define analogous structure

A

Structures which have adapted to perform the same function but have different (genetic) origins

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14
Q

Define convergent evolution

A

Organisms evolve similarities because the organisms adapt to similar environments or other selection processes

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15
Q

Why do organisms from different taxonomic groups show similar structures?

A

-they adapt to similar environments or other selection pressures

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16
Q

Give an example of two sets of organisms from different taxonomic groups that are similar

A

Marsupials and placental mammals in Australia

17
Q

Define gene pool

A

All genes and their allelic forms in a given population

18
Q

Define selection pressure

A

Any factor for which there is competition between individuals in which some will survive and some will die

19
Q

Describe the effect of the industrial revolution on peppered moths

A

-before the industrial revolution peppered moths were light in colour
-after the industrial revolution peppered moths became darker
-soot caused the bark of trees to get darker
-dark colour moths were better camouflaged
-light moths were eaten

20
Q

What did Darwin observe about finches on Galapagos Islands and how did this support his Theory of Evolution by Natural Selection?

A
  • Finches on different islands had different overall size, claw size, beak size, and beak shape
  • Selective pressure of different food sources available on different islands caused finches to adapt differently on each island
  • E.g. long thin beak suitable for catching and eating insects vs. large powerful beak suitable for crushing nuts
  • All finches originally same (common ancestor) -> specific variations on each island were favoured -> these advantageous individuals survived and reproduced -> hence why Darwin observed the distinct differences on each island
21
Q

What did Darwin observe about Australian flora and fauna?

A

Fauna: a rat-kangaroo and platypus in Australia occupied ecological niches similar to those of the rabbit and water rat in the Northern Hemisphere — similar ecological niches in different parts of the world were occupied by very different species

Flora: Eucalypts are evergreen — an adaptation as a result of the harsh environment they were in

22
Q

punctuated equilibrium vs gradualism (gradual process of natural selection)

A

Punctuated equilibrium:
- Evolution proceeds rapidly in bursts for short periods of time, intermittent with long periods of stability (no evolution)
- Lack of intermediate forms
- Supported by gaps in fossil record

Gradualism:
- Continuous evolution at a constant pace over a long period of time
- Intermediate forms — gradual accumulation of mutuations/variation

23
Q

What is speciation?

A

The formation of new species separate from the rest of the population due to geographic and sexual isolation

24
Q

Evolutionary change in cane toads?

A
  • Fast-moving cane toads interbreed and produce offspring with longer legs, faster
  • Cannibalism
25
Q

Explain the extinction of Australian megafauna?

A

Climate change:
- Continent dried out after last ice age -> less surface water -> megafauna reliant on sufficient supply of water died out
- Sudden change in temperature -> breeding seasons affected + food sources may have become less available -> died out

Humans:
- Hunted megafauna, were successful predators