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AQA Biology > Topic 6: Inheritance, Variation and Evolution pt2 F > Flashcards

Topic 6: Inheritance, Variation and Evolution pt2 F Flashcards

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1
Q

What is variation?

A

differences in the characteristics of individuals in a population

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2
Q

what is interspecific variation?

A

variation between species

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3
Q

what is intraspecific variation?

A

variation within a species

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4
Q

what processes can lead to genetic variation?

A

meiosis

sexual reproduction

mutations

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5
Q

what variation is caused by our genes? (4)

A

blood group
eye colour
natural hair colour
shape of earlobe

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6
Q

what variation is caused by the environment? (4)

A

scars
tattoos
language
hair colour/length

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7
Q

what variation is caused by a combination of our environment and our genes? (4)

A

mass
sporting achievements
height
skin colour

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8
Q

What is evolution?

A

A change in the inherited characteristics of a population over time through a process of natural selection

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9
Q

What does the theory of evolution state?

A

The species alive today have evolved from simple life forms that first developed more than 3 billion years ago

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10
Q

What do we need for evolution to take place? (3)

A

variation, selection, time

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11
Q

What were Darwin’s main observations?

A

There was overproduction of offspring, but numbers within a population stayed constant and there was variation between the offspring

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12
Q

Why didn’t people believe Darwin straight away?

A

his views opposed the church

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13
Q

What was Wallace’s theory on warning colouration?

A

Predators learned to avoid animals with bright colourations as they were likely to cause injury, taste bad or be poisonous. He realised warning colouration must be passed on by natural selection. This also led to our modern understanding of mimicry

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14
Q

What is extinction?

A

When there are no remaining individuals in a species still alive

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15
Q

What are some reasons for extinction? (8)

A

Illegal wildlife trade
Overfishing
Climate change
Pollution
Destruction of natural habitats
Population growth
Overconsumption
Invasive species (predators/disease)

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16
Q

How can we prevent extinction? (7)

A

Education
Reduce consumption
Stricter pollution laws
Increase renewable energy usage
Eat less meat and dairy
Captive breeding programs
Reduction of climate change

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17
Q

What is a fossil?

A

The remains of an organism that lived millions of years ago

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18
Q

How can fossils be formed? (5)

A

Mineralisation
Preserved in ice
Volcanic ash
Footprints can be buried under sediment layers
Insects can be trapped in resin/tree sap which can become amber if it has no access to oxygen

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19
Q

Why may the fossil record be incomplete? (6)

A

-the specimen may not be in a suitable environment for fossilisations
-the fossil could have been destroyed by geographical/environmental events/ urbanisation/haversted for fossil fuels
-not all been found
-not identified as fossils
-fossilisation process disrupted
-soft-bodies organisms have no bones to fossilise

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20
Q

How do genetics show evidence of evolution?

A

An understanding of DNA means we can see mutations, leading to a survival advantage, leading to evolution over time

21
Q

How does speciation show evidence of evolution?

A

At the end of speciation, we can see that evolution must have occurred as offspring from different species cannot reproduce to give fertile offspring

22
Q

What is a binomial name?

A

The last two taxonomic ranks which are always given in Latin (underlined or in italics with the first letter of the genus capitalised

23
Q

What are the taxonomic ranks?

A

Kingdom
Phylum
Class
Order
Family
Genus
Species

24
Q

What are the pros of selective/plant breeding?

A

You can get the desired characteristics, which can lead to economic benefits
Reliable

25
Q

What are the cons of selective/plant breeding?

A

Inbreeding depression
Reduces genetic diversity, making them vulnerable to the same diseases
The non-desired traits often go to waste(plants)

26
Q

What is selective breeding?

A

the process of breeding organisms with desired characterstics

27
Q

Describe the process of selective breeding?

A

1) Animals within a population show genetic variation. We select 2 individuals with the desired characteristics and allow them to mate
2) When the offspring are produced, the ones with the most desirable characteristics are chosen and mated
3) This happens for many generations until the animal with all the desired characteristics is produced

28
Q

Describe inbreeding depression?

A

Selective breeding often involves breeding individuals closely related. Inbred populations are more likely to suffer from genetic conditions caused by recessive alleles as they are more likely to inherit a copy from each parent.

29
Q

What can plants be bred for? (7)

A

increased yield
better quality
faster growing
disease resistance
a distinctive taste/aroma/colour
longer shelf life
the ability to be frozen

30
Q

How was traditional plant breeding carried out?

A

via paintbrush- pollen was taken from a plant with a desired trait and transferred to another

31
Q

What are the 2 methods of plant cloning?

A

Cuttings and tissue culture

32
Q

Describe the process of cuttings?

A

1) Choose the parent plant with the desired characteristics and cut a small part of the plant
2) Trim the end with sterile equipment and dip in hormone rooting powder to encourage root growth
3) Plant in moist compost of hydroponics
4) Keep in a moist atmosphere until roots develop (to reduce water loss via transpiration)

33
Q

What are the pros and cons of plant cloning via cuttings?

A

It is quick, cheap and the offspring are genetically identical, but the plant the cuttings are taken from is subject to disease

34
Q

Describe the process of tissue culture?

A

1) Take a few cells from a plant with the desired characteristics and grow them with hormones to stimulate cell division
2) Grow in different hormones to stimulate them to grow into small plants

35
Q

What are the pros and cons of plant cloning via tissue culture?

A

expensive, low genetic diversity and needs aseptic conditions , but you can grow thousands of plants from a small amount of tissue and it guarantees the plants you grow have the desired characteristics

36
Q

Why are rare plants grown using tissue culture?

A

Only one plant is needed
The rare plant isn’t at a huge risk of disease after the tissue sample is removed
Many plants can be grown from a few cells
Reduces extinction

37
Q

Describe the process of an embryo transplant?

A

1) Sperm is taken from a bull with a high dairy yield family
2) A cow is artificially inseminated with the sperm
3) Zygotes develop into cow embryos and are removed from the uterus after 3-5 days (when they are still embryonic stem cells)
4) Embryos are split into smaller embryos, each of which can grow into a new calf and the embryos are placed in the uteruses of many surrogate mothers

38
Q

Describe the process of adult cell cloning?

A

1) A body cell is removed from Sheep A and the nucleus is removed (full set of genetic material)
2) A mature ovum is removed from Sheep B and emptied
3) A mild electric shock is used to combine the nucleus and the empty egg
4) It starts to divide to form an embryo
5) The cloned embryo is implanted into the uterus of Sheep C
6) The lamb born is the clone of sheep A

39
Q

What was Linnaeus’ classification?

A

The 5 kingdoms- Animalia, Plantae, Fungi, Protists and Prokaryote

Based off of simple microscopy, anatomy and behaviour

40
Q

What was Woese’s classifications?

A

The 3 domains- Archaea, Bacteria and Eukaryotes

Linnaeus’ system was too simple, the nucleic acids in bacteria and eukaryotes were very different and archaea were unlike anything seen before

41
Q

What are the pros of cloning?

A
  • Produces many organisms with the desired characteristics (high yield, aesthetics, resistance)
  • Can increase food supply and therefore have economic benefits
  • Can increase the number of endangered species
42
Q

What are the cons of cloning?

A
  • Lack of variation, so more are likely to be susceptible to the same disease/predator/etc.
  • Ethical issues (foster mothers and hormone use/ access to cloning?)
  • Economic cost
  • Human cloning?
  • Do animals suffer if it is unsuccessful?
    it is ‘playing God’?
43
Q

What are the pros of genetic engineering?

A
  • improved resistance (less crop loss, reduces pesticide use)
  • Can make organisms produce useful proteins
  • Can improve the crop yield/ quality
  • Much faster than selective breeding
44
Q

What are the cons of genetic engineering?

A
  • Expensive, meaning GM crops will be more expensive, so the people who need it most may not be able to afford it
  • Can take a long time to get approval
  • Ethical issues
  • Who has the rights to GM crops?
  • There has been limited long term testing
  • Risk of allergies
  • Risk of transgenic genes being transferred to non-GM crops
  • What if all foods become GM crops?
45
Q

What is gene therapy?

A

A type of genome editing which involves replacing/ removing sections of DNA of the gene using molecular scissors

46
Q

What is somatic cell gene therapy?

A

1) Cells are harvested from patient
2) The virus is altered so it cannot reproduce
3) A gene is inserted into the virus
4) The altered virus is mixed with the patient’s cells and the cells become transgenic
5) Altered cells are injected into the patient’s body and the produce the desired protein

It has been a huge success with cystic fibrosis but needs to be done every 2 weeks

47
Q

What is germ line gene therapy?

A

It allows offspring to not contain a defective allele but is currently illegal as the offspring cannot consent

48
Q

What can GM crops be modified for?

A

herbicide resistance
insect resistance
golden rice

49
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

AQA Biology (7 decks)

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