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Biology A Level > Genetic Variation Exam Qs > Flashcards

Genetic Variation Exam Qs Flashcards

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1
Q

Define species richness (1 mark)

A

Species richness is the number of different species represented in an ecological community, landscape or region

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2
Q

Species richness and an index of diversity can be used to measure biodiversity within a
community.

What is the difference between these two measures of biodiversity? (1 mark)

A

Species richness measures only number of (different) species / does not measure
number of individuals.

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3
Q

Give two assumptions made when using the mark-release-recapture method. (2 marks)

A
  1. No emigration / immigration;
  2. No losses to predation;
  3. Marking does not affect survival;
  4. Birth rate and death rate equal;
  5. (In this case) all belong to one population.
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4
Q

Suggest the advantage of using the fluorescent powder in the mark release recapture method. (2 marks)

A
  1. Only glows brightly with UV, so doesn’t make insects more visible;
  2. So doesn’t affect / increase predation;
    OR
  3. Glows brightly with UV marking visible;
  4. So makes it easy to pick out labelled insects.
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5
Q

What two measurements are needed to calculate an index of diversity? (2 marks)

A

Number of (individuals of) each species;

Total number of individuals / number of species

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6
Q

What is speciation? (1 mark)

A

Speciation is the evolutionary process by which populations evolve to become distinct species.

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7
Q

A mutation of a tumour suppressor gene can result in the formation of a tumour.
Explain how. (2 marks)

A
  1. (Tumour suppressor) gene inactivated / not able to control / slow down cell division;
  2. Rate of cell division too fast / out of control.
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8
Q

Not all mutations result in a change to the amino acid sequence of the encoded polypeptide.
Explain why. (2 marks)

A
  1. (Genetic) code degenerate;

2. Mutation in intron.

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9
Q

Use your knowledge of monoclonal antibodies to suggest how this antibody stops
the growth of a tumour. (3 marks)

A
  1. Antibody has specific tertiary structure / binding site / variable region;
  2. Complementary (shape / fit) to receptor protein / GF / binds to receptor protein / to GF;
  3. Prevents GF binding (to receptor).
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10
Q 
Messenger RNA (mRNA) is used during translation to form polypeptides.
Describe how mRNA is produced in the nucleus of a cell. (6 marks)
A
  1. Helicase;
  2. Breaks hydrogen bonds;
  3. Only one DNA strand acts as template;
  4. RNA nucleotides attracted to exposed bases;
  5. (Attraction) according to base pairing rule;
  6. RNA polymerase joins (RNA) nucleotides together;
  7. Pre-mRNA spliced to remove introns.
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11
Q

Describe the structure of proteins. (6 marks)

A
  1. Polymer of amino acids;
  2. Joined by peptide bonds;
  3. Formed by condensation;
  4. Primary structure is order of amino acids;
  5. Secondary structure is folding of polypeptide chain due to hydrogen bonding;
  6. Tertiary structure is 3-D folding due to hydrogen bonding and ionic /
    disulfide bonds;
  7. Quaternary structure is two or more polypeptide chains
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12
Q

Describe how proteins are digested in the human gut. (4 marks)

A
  1. Hydrolysis of peptide bonds;
  2. Endopeptidases break polypeptides into smaller peptide chains;
  3. Exopeptidases remove terminal amino acids;
  4. Dipeptidases hydrolyse / break down dipeptides into amino acids.
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13
Q

One form of mitochondrial disease is caused by a mutation of a mitochondrial gene that codes for a tRNA. The mutation involves substitution of guanine for
adenine in the DNA base sequence. This changes the anticodon on the tRNA. This results in the formation of a non-functional protein in the mitochondrion.

Suggest how the change in an anticodon of a tRNA leads to MD (3 marks)

A
  1. Change to tRNA leads to wrong amino acid being incorporated into
    protein;
  2. Tertiary structure (of protein) changed;
  3. Protein required for oxidative phosphorylation / the Krebs cycle, so less /
    no ATP made.
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14
Q 
Messenger RNA (mRNA) is used during translation to form polypeptides.
Describe how mRNA is produced in the nucleus of a cell. (6 marks)
A
  1. Helicase;
  2. Breaks hydrogen bonds;
  3. Only one DNA strand acts as template;
  4. RNA nucleotides attracted to exposed bases;
  5. (Attraction) according to base pairing rule;
  6. RNA polymerase joins (RNA) nucleotides together;
  7. Pre-mRNA spliced to remove introns
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15
Q

Describe the structure of proteins. (5 marks)

A
  1. Polymer of amino acids;
  2. Joined by peptide bonds;
  3. Formed by condensation;
  4. Primary structure is order of amino acids;
  5. Secondary structure is folding of polypeptide chain due to hydrogen bonding
  6. Tertiary structure is 3-D folding due to hydrogen bonding and ionic /
    disulfide bonds;
  7. Quaternary structure is two or more polypeptide chains.
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16
Q

Describe how proteins are digested in the human gut. (4 marks)

A
  1. Hydrolysis of peptide bonds;
  2. Endopeptidases break polypeptides into smaller peptide chains;
  3. Exopeptidases remove terminal amino acids;
  4. Dipeptidases hydrolyse/break down dipeptides into amino acids.
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17
Q

Mitochondrial disease (MD) often causes muscle weakness. Use your knowledge of respiration and muscle contraction to suggest explanations for this
effect of MD
(3 marks)

A
  1. Reduction in ATP production by aerobic respiration;
  2. Less force generated because fewer actin and myosin interactions in
    muscle;
  3. Fatigue caused by lactate from anaerobic respiration.
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18
Q 
Put these in the correct order
genus domain species class kingdom
A

Family - Kingdom - Genus - Class - Order -Phylum -Domain - species

19
Q

What can you conclude about the effect of hunting on genetic diversity? (2 marks)

A
  1. (Hunting) reduced population size(s), so (much) only few alleles left;
    Accept bottleneck
  2. Otters today from one / few surviving population(s);
    Accept founder effect
  3. Inbreeding.
    Allow any two
20
Q

Suggest a source of DNA from an extinct animal? (1 mark)

A

Bone / skin / preserved remains / museums.

21
Q

Other than hunting, suggest two reasons why populations might show very low levels of genetic diversity (2 marks)

A
  1. Population might have been very small / genetic bottleneck;
  2. Population might have started with small number of individuals / by one
    pregnant female / founder effect;
  3. Inbreeding.
22
Q

What is meant by genetic diversity?

1 mark

A

Number of different alleles of each gene.

23
Q

Name two ways in which meiosis produces genetic variation (2 marks)

A
  1. Independent segregation (of homologous chromosomes);

2. Crossing over / formation of chiasmata.

24
Q

What 2 things does a scientific name for an organism consist of? (1 mark)

A

Genus and species

25
Q

Some populations of animals that have never been hunted show very low levels of genetic diversity.

Other than hunting, suggest two reasons why populations might show very low levels of genetic diversity. (2 marks)

A
  1. Population might have been very small / genetic bottleneck;
  2. Population might have started with small number of individuals / by one
    pregnant female / founder effect;
  3. Inbreeding.
26
Q 
Species of plant Number counted in 1 m2
Common heather 2
Red fescue 14
Vetch 2
White clover 8

Whats the species richness of this area?

A

4

27
Q

Species richness and an index of diversity can be used to measure biodiversity within a
community.
(a) What is the difference between these two measures of biodiversity? (1 mark)

A

Species richness measures only number of (different) species / does not measure
number of individuals.

28
Q

What is meant by genetic diversity? (1 mark)

A

Number of different alleles of each gene.

29
Q

Give two assumptions made when using the mark-release-recapture method. (2 marks)

A
  1. No emigration / immigration;
  2. No losses to predation;
  3. Marking does not affect survival;
  4. Birth rate and death rate equal;
  5. (In this case) all belong to one population.
30
Q

Suggest the advantage of using the fluorescent powder in this experiment. (2 marks)

A
  1. Only glows brightly with UV, so doesn’t make insects more visible;
  2. So doesn’t affect / increase predation;
    OR
  3. Glows brightly with UV marking visible;
  4. So makes it easy to pick out labelled insects.
31
Q

What two measurements are needed to calculate an index of diversity? (2 marks)

A
  1. Number of (individuals of) each species;
    Accept: ‘population’ for ‘number’
  2. Total number of individuals / number of species;
32
Q

6.During the light-independent reaction of photosynthesis, carbon dioxide is converted into
organic substances. Describe how. (6 marks)

A
  1. Carbon dioxide combines with ribulose bisphosphate / RuBP;
  2. Produces two glycerate (3-)phosphate / GP; produced from one RuBP.
  3. GP reduced to triose phosphate / TP;
    Must have idea of reduction.
  4. Using reduced NADP;
  5. Using energy from ATP;
  6. Triose phosphate converted to glucose / hexose / RuBP / ribulose bisphosphate / named organic substance;
33
Q

Give three ways in which courtship behaviour increases the probability of successful
mating (3 marks)

A
  1. Recognise / identify / attract same species;
  2. Stimulates / synchronises mating / production / release of gametes;
  3. Recognition / attraction of mate / opposite sex;
  4. Indication of (sexual) maturity / fertility / receptivity / readiness to mate;
  5. Formation of a pair bond / bond between two organisms (to have / raise
    young) .
34
Q

The scientists obtained DNA from otters that were alive before hunting started.
Suggest one source of this DNA. (1 mark)

A

Bone / skin / preserved remains / museums.

35
Q

What can you conclude about the effect of hunting on genetic diversity in otters? (2 marks)

A
  1. (Hunting) reduced population size(s), so (much) only few alleles left; Accept bottleneck
  2. Otters today from one / few surviving population(s);
    Accept founder effect
  3. Inbreeding.
36
Q

Other than hunting, suggest two reasons why populations might show very low
levels of genetic diversity. (2 marks)

A
  1. Population might have been very small / genetic bottleneck;
  2. Population might have started with small number of individuals / by one
    pregnant female / founder effect;
  3. Inbreeding.
37
Q

What is meant by genetic diversity? (1 mark)

A

Number of different alleles of each gene.

38
Q

What is meant by a hierarchy? (1 mark)

A
  1. Groups within groups;
    Accept: idea of larger groups at the top or smaller groups at
    the bottom
  2. No overlap (between groups)
39
Q

Explain the role of independent segregation in meiosis. (2 marks)

A
  1. (To provide) genetic variation;
    Genetic variation must be directly stated and not implied
  2. (Allows) different combinations of maternal and paternal
    chromosomes / alleles;
    Accept: any allele of one gene can combine with any allele of
    another gene
40
Q

A zedonk is the offspring produced from breeding a mountain zebra with a
donkey.
• The body cells of a mountain zebra contain 32 chromosomes.
• The body cells of a donkey contain 62 chromosomes.
Use this information to suggest why zedonks are usually infertile. (2 marks)

A
  1. (Zedonk has) 47 / odd / uneven number of chromosomes;
  2. Chromosomes cannot pair / are not homologous / chromosome number cannot be halved / meiosis cannot occur / sex cells / haploid cells are not produced;
41
Q

What is a species? (2 marks)

A
  1. Group of similar organisms/organisms with similar features/organisms with same genes/chromosomes;
42
Q

The forest was cleared to make more land available for agriculture.
After the forest was cleared the species diversity of insects in the area decreased.
Explain why. (3 marks)

A
  1. Decrease in variety of plants / fewer plant species;
  2. Fewer habitats / niches;
  3. Decrease in variety of food / fewer food sources;
43
Q

Explain what is meant by: a hierarchy (1 mark)

A
  1. Groups within groups;
  2. accept idea of larger groups at the top / smaller groups at the bottom
  3. No overlap (between groups);
44
Q

Explain what is meant by: a phylogenetic group. (1 mark)

A

(Grouped according to) evolutionary links / history / relationships / common ancestry;

Biology A Level (63 decks)

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