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1B > Diversity, Classification and Variation > Flashcards

Diversity, Classification and Variation Flashcards

1
Q

What are chromosome mutations?

A

When meiosis goes wrong, and the clerks produce variations in the numbers of whole chromosomes, or parts of chromosomes.

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2
Q

What is non-disjunction?

A

A chromosome mutation - a failure of chromosomes to separate properly, eg leading to Down’s Syndrome.

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3
Q

What are gene mutations?

A

Any change in the DNA base sequence of chromosomes.

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4
Q

Define mutation.

A

Any cane to the quantity / or base sequence of DNA in an organism

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5
Q

What are the two types of mutation?

A

Substitution and deletion.

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6
Q

Outline substitution.

A

One base is replaced by another nucleotide base.

(Eg GTG to GTC).

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7
Q

What can the effects of substitution be?

A
  • the polypeptide chain will differ in a single amino acid. If it was important in forming bonds that determine the tertiary structure of the final protein, then the replacement AA may not form the same bonds. Protein may then be a diff shape and not function properly. Eg enzymes.
  • the new triplet of bases could code for the same AA as before due to degenerative nature of genetic code.
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8
Q

Outline deletion.

A

One nucleotide is removed from the normal DNA sequence.

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9
Q

Outline the effects of deletion(

A
  • all triplets in a sequence are now read differently because each has been shifted to the left by one base.
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10
Q

Polyploidy is a chromosome mutation. Outline what it is.

A

Change in whole sets of chromosomes, so organisms have >3 sets of chromosomes rather than the usual 2.

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11
Q

Outline the second type of chromosome mutation.

A

Change in the number of individual chromosomes.

Sometimes individuals pairs of homologous chromosomes fail to separate during meiosis - called non-disjunction.

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12
Q

What are alleles?

A

Different versions of a single gene.

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13
Q

Define genetic diversity.

A

The number of different alleles of genes in a species.

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14
Q

How is genetic diversity increased in a population?

A
  • mutations in the DNA; forming new alleles.

- different alleles being introduced into a population (gene flow)

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15
Q

What s gene flow and what does it do?

A

Gene flow is when individuals form another population migrate into them and reproduce.

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16
Q

Genetic bottlenecks __________ genetic diversity.

A

Reduce

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17
Q

Outline genetic bottlenecks.

A
  1. An event causes a big reduction in a population (eg volcanic eruption kills).
  2. This reduced the number of different alleles in the gene pool, so reduced genetic diversity.
  3. The survivors reproduce and a larger population is greater from fewer individuals.
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18
Q

Outline the Founder Effect (type of genetic bottleneck).

A
  1. A few organisms from a population start a new colony, and there are only a small number of different alleles in the initial gene pool.
  2. The freq of each allele in the new colony might be v different to the freq in the original population (eg rare allele becomes common). May lead to higher incidence of genetic disease.
  3. Can occur as a result of migration leading to geographical separation, or new colony separated from original population eg for religion.
    3.
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19
Q

How does natural selection occur?

A
  1. Random mutation can result in new alleles of a gene.
  2. Many mutations are harmful, but, if the new allele of a gene is beneficial, there’s an increased reproductive success - so they’re more likely to survive, reproduce and pass on their genes.
  3. The advantageous allele is inherited by members of the next generation.
  4. As a result, over many generations, the new allele increases in freq in the population.
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20
Q

In what 3 ways can natural selection lead to populations becoming better adapted?

A
  • behavioural adaptations
  • anatomical adaptations
  • physiological adaptations
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21
Q

Give an example of a physiological adaptation from natural selection.

A

These include processes inside an organism’s body that increase its chance of survival.

Eg brown bears hibernating over winter, so lowers their metabolism. This conserved energy, so they don’t need to look for food in the winter when it’s scarce.

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22
Q

Give an example of an anatomical adaptation due to natural selection.

A

These are structural features that will increase its chance of survival.

Eg whales have a thick layer of blubber to help keep them warm.

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23
Q

Give an example of an behavioural adaptation due to natural selection.

A

Ways an organism acts to increase its change of survival and reproduction.

Eg possums play dead if they’re being threatened by a predator.

24
Q

What is directional selection?

A

Where individuals with alleles for characteristics (a phenotype) of extreme types are more likely to survive and reproduce.

25
Q

Give an example of directional selection.

A

Antibiotic resistance.

26
Q

Outline antibiotic resistance as directional selection.

A
  1. Some individuals in a population have alleles which give them resistance to an antibiotic.
  2. The population is exposed to the antibiotic, killing bacteria without the resistant allele.
  3. The resistant bacteria survive and reproduce without competition, passing on their advantageous allele.
  4. After time, most organisms in the population have the antiobitoc resistance allele.
27
Q

What is stabilising selection?

A

If environmental conditions remain stable, the individuals with phenotypes closest to the mean are favoured. Therefore more likely to pass their alleles onto the next generation.

28
Q

Give an example of stabilising selection.

A

Human birth weight.

29
Q

Outline human birth weight as stabilising selection.

A
  1. V small babies are less likely to survive bc they find it hard to maintain body temp.
  2. Giving birth to large babies is hard, so are less likely to survive too.
  3. Therefore conditions are most favourable for medium sized babes, so weight of human babies tends to shift towards middle of range.
30
Q

What are the two types of classification?

A

Artificial classification and phylogenic classification.

31
Q

What’s artificial classification?

A

Dividing organisms according to differences that are useful at the time, eg colour, size etc.

32
Q

What is phylogenic classification?

A

Classification based upon the evolutionary relationships between organisms and their ancestors.
Arranged groups in hierarchy with no overlap.

33
Q

Define classification.

A

The grouping of organisms

34
Q

Define taxonomy.

A

The practice of biological classification.

35
Q

Name the 8 taxa.

A 
Domain
Kingdom
Phylum
Class
Order
Family 
Genus
Species
36
Q

Des genus have uppercase or lowercase letter?

A

First part p is genus with capital letter.

37
Q

Does species have upper or lower case letter?

A

Second part of name and lower case letter.

38
Q

What is courtship behaviour?

A

Behaviour carried ur by organisms to attract a mate of the right species. It is species specific.
Eg releasing chemicals of a series of displays.

39
Q

What is the purpose of courtship behaviour?

A
  • recognise members of own species (prevent it between diff species)
  • identify a mate that’s capable of breeding (sexually mature, receptive to mating)
  • form a pair bond
  • synchronise mating (so it takes place when maximum probability of egg and sperm meeting)
  • become able to breed (physiological state)
40
Q

How is courtship behaviour used in classification?

A

Because courtship behaviour is species specific, the more closely related the species are, the more similar their courtship behaviour is.

41
Q

What are the 3 ways of clarifying evolutionary relationships?

A
  • genome sequencing
  • comparing AA sequence
  • immunological sequencing
42
Q

Outline genome sequencing as a way of clarifying evolutionary relationships.

A

The DNA base sequence of one organism can be compared with that of another. Closely related species will have a higher % of similarity in DNA base order.

43
Q

Outline comparison of AA sequence as a method of clarifying evolutionary relationships.

A

The more similar the AA sequence, the more closely p related the species are.

This is bc proteins are made from AAs. And the sequence of AAs in a protein is coded for by the base sequence of DNA related organisms have similar DNA sequences, so similar AA sequences in their proteins.

44
Q

Outline immunological comparisons as a method of clarifying evolutionary relationships

A

Similar proteins will bond to the same antibodies.

45
Q

How has the way in which genetic diversity is assessed changed over time?

A
  • early estimates of genetic diversity were made by looking at the frequency of observable characteristics eg number of people with blue eyes.
  • now, new technologies (eg comparing DNA base sequences) give more accurate estimates of genetic diversity within a population.
46
Q

Why was observable characteristics used as a measure of genetic diversity?

A

Because different alleles determine different characteristics, so a wide variety of each characteristic in a population indicates a high number of different alleles - so high genetic diversity.

47
Q

Define biodiversity.

A

The variety of living organisms in an area.

48
Q

Define habitat.

A

The place where an organism normally lives, and is characterised by the physical conditions and types of organisms present.

49
Q

Define community.

A

All the living organisms present in an ecosystem at a given time.

50
Q

Define ecosystem.

A

All living and non-living components of a particular area.

51
Q

Biodiversity can be at different levels, which are…

A

Local biodiversity and global biodiversity.

52
Q

Define species richness.

A

The number of different species in a community.

53
Q

How do you calculate the index of diversity?

A

Total number of organisms of all species (“ - 1)

Divided by

Sum of Total number of organisms of one species (“ - 1)

54
Q

Give three ways in which agriculture can reduce biodiversity.

A
  • monoculture (a single type of plant reduces biodiversity directly, and supports fewer organisms which further reduces biodiversity).
  • hedgerow removal (done to increase area of farmland by turning lots of small fields into more larger ones. This reduces biodiversity because reduces number of trees and sometimes the number of diff tree species. Also destroys habitats, so some species lose shelter and food source - so die or migrate elsewhere
  • woodland clearance (same as above)
  • pesticides (these chemicals kill organisms (pests) that feed on crops, thus reducing biodiversity. Also animals that feed on said pests will lose a food source, so their numbers could decrease too).
55
Q

Give examples of conservation schemes to prevent the reduction of biodiversity.

A
  • giving legal protection to endangered species.
  • creating protected areas eg SSSIs and AONB which restrict further development, including agricultural development.
  • the environmental stewardship scheme, which encourages farmers to conserve biodiversity eg by replanting hedgerows.

1B (35 decks)

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