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Unit 1 and 2 > 2013 January > Flashcards

2013 January Flashcards

1
Q

Name the type of reaction that would break down these carbohydrates into their
monomers.(1 mark)

A

Hydrolysis;

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2
Q

Give one feature of starch and explain how this feature enables it to act as a storage
substance.(2 marks)

A
  1. Coiled / helical / spiral;
  2. (So) compact / tightly packed / can fit (lots) into a small space;
  3. Insoluble;
  4. (So) no osmotic effect / does not leave cell / does not affect water potential;
  5. Large molecule / long chain;
  6. (So) does not leave cell / contains large number of glucose units;
  7. Branched chains;
  8. (So) easy to remove glucose;
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3
Q

An arteriole is described as an organ. Explain why.(1 mark)

A

Made of (different) tissues / more than one tissue;

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4
Q

An arteriole contains muscle fibres. Explain how these muscle fibres reduce blood flow to capillaries.(2 marks)

A
  1. (Muscle) contracts;

2. (Arteriole) narrows/constricts/reduces size of lumen/vessel / vasoconstriction;

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5
Q

A capillary has a thin wall. This leads to rapid exchange of substances between the blood and tissue fluid. Explain why.(1 mark)

A

Short diffusion distance/pathway;

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6
Q

Blood flow in capillaries is slow. Give the advantage of this(1 mark)

A

(More) time for exchange/diffusion (of substances);

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7
Q

Explain why a lack of protein in the blood causes a build up of tissue fluid.(3 marks)

A
  1. Water potential (in capillary) not as low/is higher/less negative / water potential gradient is reduced;
  2. Less/no water removed (into capillary);
  3. By osmosis (into capillary);
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8
Q

These results suggest that leopards are more closely related to cheetahs than to
pumas. Explain why

A

(For the leopard and cheetah)

  1. More hydrogen bonds (form);
  2. Similar DNA sequence(s) / similar base sequence(s) / more complementary bases / more base pairs;
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9
Q

Use this information to explain what is meant by a genetic bottleneck.(2 marks)

A
  1. Drop in population / many killed / only single female left;
  2. Idea of reduced/low genetic variation/diversity / reduction in (variety of) alleles / smaller gene pool;
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10
Q

The fertility of cheetahs is low. The proportion of abnormal sperm cells produced is
higher in cheetahs than in other members of the family Felidae. Suggest an
explanation for this.(2 marks)

A
  1. Mutation affecting sperm cell or production (in small population);
  2. Errors during meiosis;
  3. Inbreeding / closely related cheetahs breed;
  4. High chance of inheriting allele / high frequency of allele (in the population);
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11
Q

What is intraspecific variation?(1 mark)

A

Variation / differences within the same/a species;

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12
Q

Explain why both types of twin were used in this investigation.(2 marks)

A
  1. Identical twins show genetic influence / differences between them show environmental influence;
  2. Non-identical twins (also) show an environmental/non-genetic influence;
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13
Q

What do these data suggest about the relative effects of genetic and environmental
factors on the development of schizophrenia?(1 marks)

A

Genes play a greater role / environment plays a lesser role;

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14
Q

Suggest two factors that the scientists should have taken into account when selecting
the twins to be used in this study. (2 marks)

A

Any suitable suggestion for a maximum of two marks e.g.:

  1. Age;
  2. Sex (non-identical twins);
  3. Family/medical history (of mental illness);
  4. No use of recreational drugs;
  5. Ethnic origins;
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15
Q

Describe how the students would have returned the air bubble to the start of the
capillary tube in this investigation.(1 marks)

A

Open/use tap / add water from reservoir;

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16
Q

Give two precautions the students should have taken when setting up the potometer to
obtain reliable measurements of water uptake by the plant shoot.(2 marks)

A
  1. Seal joints / ensure airtight / ensure watertight;
  2. Cut shoot under water;
  3. Cut shoot at a slant;
  4. Dry off leaves;
  5. Insert into apparatus under water;
  6. Ensure no air bubbles are present;
  7. Shut tap;
  8. Note where bubble is at start / move bubble to the start position;
17
Q

A potometer measures the rate of water uptake rather than the rate of transpiration.
Give two reasons why the potometer does not truly measure the rate of transpiration(2 marks)

A
  1. Water used for support/turgidity;
  2. Water used in photosynthesis;
  3. Water produced in respiration;
  4. Apparatus not sealed/’leaks’;
18
Q

Explain the relationship between the number of leaves removed from the plant shoot
and the mean rate of water uptake.(3 marks)

A
  1. Less surface area;
  2. Fewer stomata;
  3. Less evaporation/transpiration;
  4. Less cohesion/tension/pulling (force);
19
Q

Treatment with isoniazid leads to the osmotic lysis of this bacterium. Use information
in the diagram to suggest how.(2 marks)

A
  1. Cell wall not formed / production inhibited;
  2. Lower water potential in bacterium;
  3. Water enters and causes lysis/expansion/pressure;
20
Q

Use information in the diagram to suggest one reason why isoniazid does not affect
the production of fatty acids in human cells.(1 marks)

A

Human cells lack enzyme (B)/have a different enzyme/produce different fatty acids/use different substrates;

21
Q

A mutation in the gene coding for enzyme B could lead to the production of a
non-functional enzyme. Explain how.(3 marks)

A
  1. Change in base sequence (of DNA/gene);
  2. Change in amino acid sequence / primary structure (of enzyme);
  3. Change in hydrogen/ionic/ disulphide bonds;
  4. Change in the tertiary structure/active site (of enzyme);
  5. Substrate not complementary/cannot bind (to enzyme / active site) / no enzyme-substrate complexes form;
22
Q

Using isoniazid to treat diseases caused by other species of bacteria could increase
the chance of the bacterium that causes tuberculosis becoming resistant to isoniazid.
Use your knowledge of gene transmission to explain how.(3 marks)

A
  1. Resistance gene/allele;
  2. On plasmid;
  3. (Spread by) horizontal transmission;
  4. (Involves) conjugation/pilus;
23
Q

Suggest one ethical argument for maintaining biodiversity (1 marks)

A

(We should maintain biodiversity to)
Prevent extinction /loss of populations/ reduction in populations /loss of habitats / save organisms for future generations (idea of);

24
Q

Suggest one economic argument for maintaining biodiversity. (1 marks)

A

A suitable example of how some species may be important financially e.g.

  1. medical / pharmaceutical uses;
  2. commercial products / example given;
  3. tourism;
  4. agriculture;
  5. saving local forest communities;
25
Q

Explain the relationship between the percentage of original forest area remaining and
the percentage of bird species that have become extinct.(2 marks)

A
  1. Fewer plant species / decrease in plant diversity;
  2. Fewer habitats/nesting sites;
  3. Fewer niches;
  4. Fewer food sources/varieties;
  5. Less protection from predators/ hunters/environment;
26
Q

What two measurements would the ecologists have needed to obtain to calculate the
index of diversity of birds on each island?(2 marks)

A
  1. Number of (individuals/birds of) each species;

2. Total number of individuals/birds of all species;

27
Q

Explain how a larger body size is an adaptation to a colder climate.(2 marks)

A
  1. (Larger birds have) a low(er) SA:VOL;

2. (So) less heat loss / more heat retained;

28
Q

Describe how DNA is replicated.(6 marks)

A
  1. Strands separate / H-bonds break;
  2. DNA helicase (involved);
  3. Both strands/each strand act(s) as (a) template(s);
  4. (Free) nucleotides attach;
  5. Complementary/specific base pairing / AT and GC;
  6. DNA polymerase joins nucleotides (on new strand);
  7. H-bonds reform;
  8. Semi-conservative replication / new DNA molecules contain one old strand and one new strand;
29
Q

Explain how the doctor could have recognised which cells were in interphase when
looking at the tissue samples.(1 mark)

A
  1. No visible chromosomes/chromatids;

2. Visible nucleus;

30
Q

Describe one way the scientists could have allocated the patients to each group.(2 marks)

A
  1. Random;
  2. Method e.g. number generator / number out of a hat;
    OR
  3. Matched / all the same;
  4. For e.g. age / sex;
31
Q

What do the standard deviation bars suggest about the difference in the mean increase
in FEV1 between Group 1 and the other groups? Explain your answer.(2 marks)

A
  1. (Differences) are real/significant/not due to chance;

2. (As) bars/SDs do not overlap;

32
Q

What do the data suggest about the ‘placebo effect’ in this investigation? Explain your
answer.(2 marks)

A
  1. (Differences) are real/significant/not due to chance;

2. (As) bars/SDs do not overlap;

33
Q

On each occasion that a patient’s FEV1 was measured, a doctor repeated the
measurement several times. Explain why.(2 marks)

A
  1. (Allows) anomalies to be identified/ ignored/ effect of anomalies to be reduced / effect of variation in data to be minimised / concordant results;
  2. (Makes) average/mean (more) reliable;
34
Q

Suggest why all the patients were allowed to continue with their normal asthma
treatment in this investigation.(1 marks)

A
  1. Unethical/unfair not to treat patients;

2. Dangerous / could cause an asthma attack

35
Q

Suggest why the patients were told to stop their normal asthma treatment 24 hours
before their FEV1 measurements were taken.(2 marks)

A
  1. Ensures normal treatment does not affect results / improvements are only due to the spray;
  2. (As) normal treatment is short-lived/ effective for less than 24 hours/ (24h) is long enough for normal treatment to wear off;
36
Q

The scientists concluded that the data obtained for the Improvement Scores were less
reliable than the data obtained measuring FEV1. Suggest why they concluded this(2 marks)

A
  1. (Improvement scores) are qualitative / subjective/rely on own judgement/ different patients may assess symptoms differently;
  2. Some patients may lie/exaggerate/want to please doctors;
37
Q

Group 3 reported the lowest mean Improvement Score. Suggest one explanation for
this.(2 marks)

A
  1. Not blind / patients knew they were not receiving treatment/ patients did not receive treatment;
  2. (So) more likely to underestimate/give lower scores / did not expect to improve / less improvement;

Unit 1 and 2 (11 decks)

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