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Biology > Chapter 6c - Evolution and classification > Flashcards

Chapter 6c - Evolution and classification Flashcards

1
Q

What is variation?

A

Differences in the characteristics in the population of a species.

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2
Q

What is genetic variation?

A

Vaiation caused by the combination of genes from two parents. There is a lot of genetic variation within a population.

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3
Q

Give examples of characteristics only determined by genes.

A

.- Eye colour
- Blood group
- Inherited disorders

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4
Q

What is environmental variation?

A

Variation caused by the environment and conditions that organisms develop in.

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5
Q

Give examples of an environmental variation?

A
  • Suntan
  • Language
  • Tattoos
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6
Q

Examples of variation by both genetic and environmental factors?

A
  • Height
  • Weight
  • Athletic ability
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7
Q

How do variations arise?

A

Mutations

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8
Q

What do most genetic variants do?

A

Have little or no effect on the protein the gene codes for. So, no effect on the phenotype.

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9
Q

What do SOME genetic variants do?

A

Have a small influence on the organisim’s phenotype e.g eye colour

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10
Q

What do LITTLE genetic variants do?

A

Have a dramatic effect on the phenotype. For example, cystic fibrosis means that the protein produced by the mutated gene doesn’t work properly.

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11
Q

What happens if a new phenotype makes an individual more suited to the environment ?

A

It can become common throughout the species relatively quickly by natural selection.

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12
Q

What is evolution?

A

A change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.

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13
Q

What is the Theory of Evolution?

A

All species of living things have evolved from simple life forms that first developed more than three billion years ago.

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14
Q

What is the Theory of Evolution by Natural Selection?

A
  1. Individuals within a species show wide phenotypic variation because of the mix of genetic variation present in the population. .
  2. Some genetic variants give rise to characteristics that are better suited to the environment. Organisms with these characteristics have a better chance of survival and so are more likely to breed successfully.
  3. So, the gentic variants responsible for the useful characteristics are more likely to be passed on to the next generation.
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15
Q

When do you know that speciation has occured?

A

If two populations of one species become so different in phenotype
that they can no longer interbreed to produce fertile offspring,

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16
Q

What is selective breeding?

A

The process by which humans
breed plants and animals for particular genetic characteristics.

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17
Q

What is the process of selective breeding?

A

Choose parents with the desired
characteristic from a mixed population. They are bred together. From the offspring those with the desired characteristic are bred together. This continues over many generations until all the offspring show the desired
characteristic.

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18
Q

What features do we selectively breed for?

A
  • Animals that produce more meat or milk
  • Disease-resistant crops
  • Dogs with a gentle temperament
  • Decorative plants with big or unusual flowers.
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19
Q

Is Selective breeding something new?

A

No, humans have been doing this for thousands of years since they first bred food crops from wild plants and domesticated animals.

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20
Q

What is the main problem with selective breeding?

A

It reduces the gene pool in a population. This is because the farmer keeps breeding from the “best” animals or plants - which are all closely related. This is known as interbreeding.

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21
Q

Why can interbreeding cause health problems?

A
  1. There’s a higher chance of organisms inheriting harmful genetic defects when the gene pool is limited.
  2. If a new disease appears, due to little variation, there is likely to be less chance of any resistant alleles being present in the population.
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22
Q

What is genetic engineering?

A

A process which involves modifying the genome of an organism by introducing a
gene from another organism to give a desired characteristic.

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23
Q

Why have plant crops been genetically engineered?

A

To produce bigger yield and be resistant to disease.

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24
Q

Why have bacteria ben gentically engineered?

A

To produce useful substances such as human insulin to treat diabetes.

25
Q

Issues surrounding genetic engineering?

A

Changing a person’s genes might accidentally create unplanned problems, which could be passed down to future generations.

26
Q

Benefits of GM crops.

A
  • Increased yield, makes more food
  • Can be engineered to contain nutrients thats missing in a population. For example, golden rice.
27
Q

Concerns of GM crops.

A
  • Will affect the number of wild flowers that live in and around crops, reducing biodiversity.
  • We might not fully understand the effects of eating them on human health.
  • Transplanted genes may get out in to the natural environment. For example, the herbicide resistant gene may be picked up by a weed.
28
Q

What are the steps for genetic engineering?

A
  • enzymes are used to isolate the required gene; this gene is inserted into a vector, usually a bacterial plasmid or a virus
  • the vector is used to insert the gene into the required cells
  • genes are transferred to the cells of animals, plants or
    microorganisms at an early stage in their development so that they develop with desired characteristics.
29
Q

What is a tissue culture?

A

Using small groups of cells from part of a plant to grow identical new plants.

30
Q

Why are tissue cultures important?

A

This is important for preserving rare plant species or commercially in nurseries.

31
Q

What are cuttings?

A

An older, but simple, method used by gardeners to produce many identical new plants from a parent plant. Take cuttings from parent plant and then plant them to produce genetically identical copies.

32
Q

What are embryo transplants?

A

Splitting apart cells from a developing animal embryo before they become specialised, then transplanting the identical
embryos into host mothers.

33
Q

What is adult cell cloning?

A
  • The nucleus is removed from an unfertilised egg cell.
  • The nucleus from an adult body cell, such as a skin cell, is inserted
    into the egg cell.
  • An electric shock stimulates the egg cell to divide to form an embryo.
  • These embryo cells contain the same genetic information as the adult skin cell.
  • When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development.
34
Q

Benefits of cloning.

A
  • Quickly gets you lots of “ideal” offspring with known characteristics. This can benefit farmers.
  • Cloning could be used to help preserve endangered species.
  • The study of animal clones could lead to a greater understanding of embryonic develeopment and of ageing.
35
Q

Concerns of cloning.

A
  • Gives you a reduced gene pool. Higher chance of being wiped out by disease.
  • Cloned animals may not be as healthy as normal ones
  • Humans could be cloned in the future. Any success would follow many unsuccessful attempts. The human rights of the clone.
36
Q

Why did Charles Darwin propose the Theory of Evolution?

A

As a result of observations on a round the world expedition, backed by years of experimentation and discussion and linked to developing knowledge of geology and fossils.

37
Q

What is the theory of evolution by natural selection?

A
  • Individual organisms within a particular species show a wide range of
    variation for a characteristic.
  • Individuals with characteristics most suited to the environment are
    more likely to survive to breed successfully.
  • The characteristics that have enabled these individuals to survive are
    then passed on to the next generation.
38
Q

Why was the Theory of Evolution only gradually accepted?

A
  • The theory challenged the idea that God made all the animals and
    plants that live on Earth.
  • There was insufficient evidence at the time the theory was published to convince many scientists.
  • The mechanism of inheritance and variation was not known until
    50 years after the theory was published.
39
Q

What was Lamarck’s theory based on?

A

Changes that occur in an organism during its lifetime can be inherited. We now know that in the vast majority of cases this type of inheritance cannot occur.

40
Q

Darwin’s theory of evolution by natural selection - connected to speciation.

A
  • Each population shows genetic variation because they have a wide range of alleles.
  • blah blah until they’ve changed so much they cannot breed with one another to produce fertile offspring.
41
Q

Wallace’s work.

A

Alfred Russel Wallace independently proposed the theory of evolution by natural selection. He published joint writings with Darwin in 1858
which prompted Darwin to publish On the Origin of Species (1859) the following year.

Wallace worked worldwide gathering evidence for evolutionary theory.

He is best known for his work on warning colouration in animals and his theory of speciation.
Alfred Wallace did much pioneering work on speciation but more evidence over time has led to our current understanding of the theory of speciation.

42
Q

What is Wallace’s theory of warning colouration?

A

Some species deter predators from eating them through warning colours. Warning colours are an example of a beneficial characteristic that came about through natural selection.

43
Q

What are fossils?

A

Remains of organisms from millions of years ago found in rocks.

44
Q

How are fossils formed by replacement?

A

Hard parts of an organism do not decay easily. Eventually, they are replaced by minerals as they decay which forms a rock-like substance shaped like the original hard part.

45
Q

How are fossils formed by casts and impressions?

A

An organism is buried in a soft material like clay. The clay later hardens around it and the organism decays, leaving a cast of itself. An animal’s burrow, footprint or traces can be preserved in this way.

46
Q

How are fossils formed by preservation?

A

If the conditions for decay (plenty of oxygen, enough moisture, right temp. and pH) aren’t right the dead organism’s remains will be preserved. E.g. microbes in amber.

47
Q

Why is the early fossil record incomplete?

A

Many early forms of life were soft-bodied, which means that they have left few traces behind. What traces there were have been mainly destroyed by geological activity. This is why scientists cannot be certain about how life began on Earth.

48
Q

What is extinction?

A

Extinctions occur when there are no remaining individuals of a species still alive.

49
Q

Why do species become extinct?

A
  • Rapid change in environment
  • A new predator kills them all
  • A new disease kills them all
    -They can’t compete with a new species for food.
  • A catastrophic event kills them all.
50
Q

Why can bacteria evolve rapidly?

A

They reproduce at a fast rate.

51
Q

How does antibiotic-resistant bacteria arise?

A

Mutations of bacterial pathogens produce new strains. Some strains might be resistant to antibiotics, and so are not killed. They survive and reproduce, so the population of the resistant strain rises. The resistant strain will then spread because people are not immune to it and there is no effective treatment.

52
Q

What is a superbug?

A

Bacteria that are resistant to most known antibiotics - MRSA.

53
Q

What should be done to reduce the rate of development of antibiotic-resistant bacteria?

A
  • Doctors should not prescribe antibiotics inappropriately, such as
    treating non-serious or viral infections
  • Patients should complete their course of antibiotics so all bacteria are killed and none survive to mutate and form resistant strains
  • The agricultural use of antibiotics should be restricted.
54
Q

Why is it hard to combat resistant bacteria?

A

The development of new antibiotics is costly and slow. It is unlikely to keep up with the emergence of new resistant strains

55
Q

Who is Carl Woese?

A

He developed the three- domain system.

56
Q

What does the three-domain system include?

A
  • Archaea (primitive bacteria usually living in extreme environments)
  • Bacteria (true bacteria)
  • Eukaryota (which includes protists, fungi, plants and animals).
57
Q

What are evolutionary trees?

A

Evolutionary trees are a method used by scientists to show how they believe organisms are related. They use current classification data for living organisms and fossil data for extinct organisms.

58
Q

Why were new models of classification were proposed?

A

Evidence of internal structures became more developed due to improvements in microscopes, and the understanding of biochemical processes progressed.

59
Q
A

Biology (4 decks)

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