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🧬 > B5.2 > Flashcards

B5.2 Flashcards

1
Q

What is evolution?

A

Evolution is the gradual change in inherited characteristics of a population over time, through the process of natural selection, which may result in the formation of a new species

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2
Q

How does natural selection effect phenotypes?

A

It’s increases advantageous phenotypes

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3
Q

How much genetic variation do populations of species show?

A

They show a lot of genetic variation, which means that there is a big mix of genetic variants (alleles) present in the population

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4
Q

How do variants (different alleles)arise?

A

When a DNA randomly mutates (and also sexual reproduction)

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5
Q

What does it mean by survival of the fittest

A

The resources living things need to survive are limited so individuals must compete for these resources to survive.

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6
Q

Describe the process of Natural Selection:

A
  • organisms in a species show variation so these is a large mixture of gene variants/alleles present
  • organisms with characteristics that are best adapted to the environment survive and reproduce. Others die.
  • genes from successful organisms are passed to offspring in next generation so the offspring is more likely to possess characteristics that made their parents successful ( they have advantageous phenotype and more chances of breeding and passing on genes)
  • greater proportion of individuals in next generation inherit the advantageous variants and so they have the phenotype to survive
  • process repeated many times and after generations, characteristics increasing survival are more common and naturally selected = development of new species
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7
Q

What does the speed at which species evolve depend on?

A

It depends partly on how quickly it reproduces such as bacteria which reproduce in just 20 mins, whereas humans are more likely to reproduce after 20 - 30 years

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8
Q

What does it means if an organism if quick to reproduce?

A
  • inherited characteristics are passed on to future generations more quickly
  • time taken for the population to adapt to its environment is reduced
  • we can monitor evolution as it’s occurring as it’s so fast = scientists can study evolution in action
  • observe how advantageous characteristics (antibiotic resistance) become more common in population
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9
Q

How influence does evolution have on the phenotype?

A

Evolution can mean that a species’ phenotype changes so much that a new species is formed

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10
Q

What does it mean by a new species

A

The old and new version of the species can’t breed together to produce fertile offspring

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11
Q

How can a new species be formed?

A
  • physical barrier separates two population of species
  • conditions on each side of the barriers will be slightly different so the phenotype that are beneficial will be different for each population
  • natural selection acts on each population to increase the proportion of advantageous phenotype
  • until population are so different they can no longer breed together
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12
Q

Describe the evolution of peppered moths:

A
  • before 19th cent = moths in Britain were plain coloured (camouflage against trees)
  • mutations occurred in some mothers = dark coloured = more likely to be eaten by birds
  • Industrial Revolution = trees covered in soot = black moths camouflaged = more of them survived
  • after several years = dark pepper moths = more common in urban areas
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13
Q

Describe the evolution of antibiotic - resistant bacteria

A
  • evolve in short time = rapid reproduction
  • mutations can occur kill bacterium or to make it antibiotic resistant causing new variants and alleles to be introduced into the population
  • bacterium reproduce and pass it on to offspring while antibiotics kill non resistant bacteria
  • may result in whole species becoming antibiotic resistant
  • scientists can observe this
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14
Q

What do scientists think we evolve from?

A
  • complex organism evolved from simple ones around 3500 million years ago
  • fossil records and antibiotic resistance in bacteria = evidence
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15
Q

What are fossils?

A

Any trace of an animal or plant that lived long ago. They are most commonly mineralised (changed into rocks)

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16
Q

What can fossils tell us?

A
  • how organism looked

- how long ago they existed = deeper underground = older fossil

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17
Q

How is a fossil a record to evolution?

A

Arrange fossils in chronological order = gradual changes can be observed = evidence for evolution as shows how species changed and developed over time

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18
Q

What evidence shows that simple life forms gradually evolved into more complex ones?

A
  • simple organisms fossils = oldest rocks and complex (vertebrates) = recent rocks so supports that simple life forms gradually evolved into more complex ones
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19
Q

What evidence shows that animals require plants to live?

A
  • plant fossils before animal fossils = consistent with animals need plants to live
20
Q

What evidence is there that closely related organisms have the evolved from the same ancestor?

A
  • study similarities in anatomy (bone structure) = modern day species link to extinct species
  • modern day horse evolved from Eohippus = dog sized animal in rainforest over 60m yrs ago —> multi toed feet for walking across forest floor evolved to single toes for running over grassland
21
Q

What are there gaps in fossil record?

A
  • not discovered
  • many animals = soft bodied so decompose quickly before they fossilise
  • many destroyed by volcanic eruptions
22
Q

How is the Atlantic Tomcod evidence for evolution?

A
  • over past 40 years it’s evolved resistance to PCB (type of industrial waste that is toxic to most living organisms)
23
Q

What happens to species that don’t adapt to environmental changes?

A
  • die out

- scientists estimate over 99% of all species that ever lived on earth = extinct

24
Q

How is molecular comparison evidence for evolution?

A
  • compare DNA and proteins of different species
  • look at order of nuclei acid bases or amino acid order in a protein
  • closely related species have most similar DNA and proteins
  • distant related have fewer similarities
25
Q

What theory did Darwin come up with?

A

The Theory Evolution by Natural Selection

26
Q

How did Darwin come up with that theory?

A
  • spent 5 years on a voyage while studying plants and animals
  • noticed variation within members of the same species and those with characteristics most suited to the environment more likely to survive (e.g. finches’s beak shape is linked to food type)
  • also noticed characteristics were passed on to offspring
  • wrote theory of evolution to explain observations
27
Q

How did Wallace contribute to the theory of evolution?

A
  • Alfred = scientist working at the same time as Darwin
  • Wallace’s observations = provided evidence
  • ALSO came up with theory and worked on it with Darwin
  • BUT Darwin’s ‘On the Origin of Species’ = made other scientists pay attention to Darwin so he’s more remembered than Wallace
28
Q

Give an example Wallace’s observations:

A
  • warning colours used by some species (butterfly) to deter predators from eating them (advantageous adaption that evolved from natural selection)
29
Q

How have ideas about evolution influenced modern day biology?

A
  • we understand that all life changes through the process of evolution and we all descend from a common ancestor
30
Q

How has Darwin’s theory of evolution influenced classification, antibiotic resistance and conservation?

A
  • classification = based on evolutionary relationships
  • antibiotic resistance = understand importance of finishing a course of antibiotics to prevent it spreading and need to constantly produce them to stop constantly evolving bacteria
  • conservation - understand importance of genetic variation and how it helps populations adapt to changing environments (led to conservation projects)
31
Q

What did everyone think before Darwin’s theory and when did Darwin publish On the origin of species?

A
  • many people believed all species on Earth were created by God
  • 1859
32
Q

How may plants become extinct?

A
  • changes in environment = we need to evolve to adapt and some become extinct if they don’t evolve quickly enough
  • seedbanks store & protect biodiversity (buried in ice to preserve)
33
Q

What are the uses of seedbanks?

A
  • store lots of seeds (this genetic material) from different species of plants (conserve biodiversity by storing wide variety of plants
  • if plants extinct = stored seeds can grow new plants
  • help conserve genetic variation = for some species see range of seeds from plants with diff characteristics (diff alleles)
34
Q

Give an example of when seedbanks conserve genetic variation:

A
  • modern agriculture = little genetic variation in crop species grown = so could easily be wiped out by a particular pest
  • traditional versions of crop species may have alleles from pest resistant = if stored = their seeds can produce crops that cope with pests
35
Q

What is classification?

A
  • process of sorting living organisms into groups with similar features by looking at their similarities and differences
36
Q

Why do scientists classify organisms?

A
  • identify species
  • predict characteristics
  • find or show evolutionary links
37
Q

What is artificial classification?

A
  • uses observable features
  • early classification only used observant features (lay eggs, fly)
  • artificial classification system
  • doesn’t consider evolutionary relationships
37
Q

When is artificial classification used?

A
  • used to make keys so scientists can identify and group organisms but not the best way
38
Q

What is natural classification?

A
  • system using evolutionary relationships

- use information about common ancestors and common structural features (bat and human hands are grouped together)

39
Q

Which classification uses kingdoms to divide organisms and what are the 5 kingdoms?

A
  • natural classification

- plant,animal,fungi, protoctista (amoeba and algae), prokaryotes (organisms with no nucleus)

40
Q

What are the seven taxonomic groups arranged into their hierarchy?

A

The kingdom is further divided into

  • phylum
  • class
  • order
  • family
  • genus
  • species
41
Q

How do you classify something as being in the same species and how many organisms does a species have?

A
  • group that contains only one type of organism

- species is defined as a group of similar organisms that are able to reproduce to give fertile offspring

42
Q

What is Phylogeny?

A
  • the study of evolutionary links through the study of DNA

- looks at how similar the DNA is and puts it into family trees

43
Q

How are new evolutionary relation apps being discovered through molecular phylogenetics?

A
  • DNA sequencing = see how closely related organisms are
  • compares the sequence of DNA bases for different species = the more similar the DNA sequence between species = the more closely related they are (base sequence for humans and chimpanzee = 94% same)
44
Q

Describe how Deflex helps people sleep:

A
  • Deflex = depressant.
  • works on the synapse
  • reduces the amount of neurotransmitters received and sent
  • binds with the receptors in the synapse instead of neurotransmitters, so thus it can no longer bind
  • also binds and breaks down released neurotransmitters

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