Immunity MS New Syllabus (2010-2012)

Edexcel GCE in Biology © Edexcel Limited 2007 Sample Assessment Materials 133

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Question

5.(b)(i) Explain the meaning of the term mutation.

Answer Mark

1. Change in sequence of DNA;

2. Change in {mass of DNA / number of chromosomes};

2

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Question

5.(b)(ii) Suggest why the vaccine contains a cocktail of antigens.

Answer Mark Award one mark for each of the following points in context to

a maximum of two marks.

1. mutation causes change in gene product/eq;

2. idea that structure of antigen may change (as result of mutation);

3. idea that individual will not be protected if flu virus does not have same antigens present in vaccine;

4. idea that a cocktail of antigens will increase the chance of matching antigens;

2

Edexcel GCE in Biology © Edexcel Limited 2007 Sample Assessment Materials 137

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Question

7.(a) The table below lists five structural features that may be found in bacteria and viruses. Put a cross in the box if the structural feature is present.

Answer Mark Award 1 mark for each correct row in the following table.

Structural feature Bacteria Viruses

Mesosomes

Capsid

Nucleic acid

Cytoplasm

Ribosomes

5

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7.(b)(i) Describe the trends shown by the data.

Answer Mark Award one mark for each of the following points in context to a

maximum of two marks.

1. Increase in number of new cases in Africa and Europe

2. Decrease in number of new cases in Asia and South America

3. Any relevant manipulation of data

2

Sample Assessment Materials © Edexcel Limited 2007 Edexcel GCE in Biology138

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Question

7.(b)(ii) HIV positive people were excluded from the data. If they had been included suggest how the data would differ. Give an explanation for your answer.

Answer Mark Explanation:

More incidence of TB in the population/eq

Award one mark for each of the following points in context to a maximum of two marks.

1. Ref to opportunistic infection

2. HIV positive people have weakened immune system

3. A higher proportion of HIV positive people are infected by TB

3

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Question

7.(c) TB is increasing in some countries which have well-funded health services. Suggest two reasons for this.

Answer Mark Award one mark for each of the following points in context to a

maximum of two marks.

1. TB bacteria {mutate / become resistant to antibiotics}

2. immigration from countries with high incidence of TB

3. increased travel

4. increase in HIV infection

5. lower rates of immunisation against TB

2

Edexcel GCE in Biology © Edexcel Limited 2007 Sample Assessment Materials 139

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Question

8.(a)(i) Distinguish between bacteriostatic and bacteriocidal antibiotics.

Correct Answer Mark Bacteriostatic prevent bacteria multiplying and bacteriocidal

kill bacteria 1

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8.(a)(ii) Suggest why mammalian cells are unharmed by antibiotics.

Correct Answer Mark Award one mark for each of the following points up to a

maximum of two marks.

Mammalian cells: 1. are eukaryotic

2. have different enzymes

3. do not have cell walls

4. have {80s / larger/eq} ribosomes / different protein synthesis

2

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8.(b) Suggest ways by which doctors and patients can help to prevent the further spread of antibiotic resistance in bacteria.

Answer Mark Award one mark for each of the following points up to a

maximum of three marks.

1. do not prescribe antibiotics for minor infections /viral infections

2. do not prescribe antibiotics to prevent infections

3. reference to narrow spectrum antibiotics

4. ref to rotation in the use of different antibiotics

5. {advise / take} the full course of antibiotics

6. ref to hand-washing (between patients / by visitors of hospitals)

7. use of isolation wards

3

Sample Assessment Materials © Edexcel Limited 2007 Edexcel GCE in Biology140

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Question

8.(c) Describe a procedure that you have used to investigate the effect of different antibiotics on bacterial growth.

Answer Mark Award one mark for each of the following points up to a

maximum of four marks.

1. Ref. to a specific aseptic technique

2. Bacterial lawn/pour plate

3. Use of antibiotic discs / antibiotics incorporated into agar /eq

4. Incubate for 24-36 hours

5. At 25-30 °C

6. Record bacterial growth/eq

4

1001 6BI0

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6(a)

1. RNA in HIV and DNA in {bacterium / eq} ;

2. comparative description of nucleic acid e.g.

circular in bacterium and linear in HIV / eq ;

3. plasmids in {bacterium / eq} and no plasmids in HIV ;

maximum (2)

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6(b)

1. {keratin / protein} in skin {surface / epidermis} ;

2. idea of forms a {hard / impenetrable / physical /

eq} barrier ;

(2)

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6(c)(i)

1. numbers decrease / eq ; 2. small decrease in {first week / between weeks {4

/ 5} and 6} / eq ;

3. large decrease between weeks {1 / 2} to 3 / eq ;

4. credit use of manipulated figures ;

maximum (2)

1001 6BI0

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6* (c)(ii) QWC

(QWC – Spelling of technical terms (shown in italics) must be correct and the answer must be organised in a logical sequence)

1. {glycoprotein / gp120} on virus / eq ;

2. binds with {receptors / CD4} / eq ;

3. on (surface) membrane of lymphocytes / eq ;

4. viral RNA enters the lymphocyte / eq ;

5. viral RNA used to produce viral DNA (in

lymphocyte) / eq ;

6. by action of reverse transcriptase ;

7. ref to formation of new viruses ;

8. lymphocyte destroyed when new viruses {bud out of / leave} the cell / eq ;

9. T killer {cells / lymphocytes} destroy T helper

{cells / lymphocytes} / eq ;

maximum (5)

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6(c)(iii)

B {cells / lymphocytes} { not activated / not stimulated / are inhibited / eq} / fewer antibodies / T killer cells {increase / multiply / eq} ;

(1)

1001 6BI0

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8(a)

1. idea of antibiotic is used to {control / kill /

prevent reproduction of / eq} bacteria ;

2. bacteriostatic prevent {reproduction / division / multiplication / growth / eq} of bacteria;

3. bactericidal {destroy / kill / eq} bacteria ;

(3)

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8(b)

1. idea that both more or less the same at {start /

end} ; 2. idea that B is higher than A most of the time ; 3. B rises and then falls and A falls and then rises /

eq ;

4. ref to both falling after April 04 / eq ;

5. comparative use of figures ;

maximum (3)

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8(c)(i)

D {has the lowest rate of MRSA infection (throughout) / is consistent / has less fluctuation} / eq ;

(1)

1001 6BI0

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8(c)(ii)

1. D has {stricter / eq} hygiene practices / eq ;

2. ref to hand washing regimes for {doctors / nurses

/ medical staff / visitors} ;

3. particularly when dealing with open {wounds / eq} / eq ;

4. ref to wearing suitable clothing ;

5. ref to antiseptic (solutions) readily available ;

6. named antiseptic e.g. gels, pastes, alcohol rubs ;

7. ref to {isolation of suspected cases / screening of admissions} / eq ;

8. D {controls / monitors} use of antibiotics / eq ;

9. fewer {patients / visitors} passing in and out ;

maximum (3)

6BI04_01 1006

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4(a)(i) C ; (1)

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4(a)(ii) A ; (1)

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4(b)(i) D = antigens / (glyco)proteins ; E = B {lymphocytes / cells} / plasma cells ; F = antibodies / immunoglobulins ; G = macrophage / phagocyte / eq ; H = enzymes / lysozyme ;

(5)

6BI04_01 1006

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4(b)(ii) 1. reference to protein nature of {antigens /

antibodies} ;

2. antigens are specific (to each bacteria) / eq ;

3. antibodies need to be {complementary / specific} (to the antigen) ;

4. idea that {binding / eq} can take place ;

5. (some bacteria) have {different / changed}

antigens / eq ;

6. idea that this is a primary infection ;

7. reference to {mucus / slime} {coat /capsule} (of bacterial cells) ;

8. idea that some bacteria are inside body cells

;

9. idea of antibodies already present e.g. from passive immunity or breast feeding ;

max (3)

6BI04_01 1006

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8(a) Description Name of

structure P, E or B

Enclosed by outer smooth membrane inner membrane folded forming cristae

Mitochondrion / mitochondria

E / eukaryotic

Long strand-like structure extending out from the cell Used for locomotion

Flagellum / flagella

B / both

Small, circular loop of double-stranded DNA

plasmid P / prokaryotic

1 mark for any two correct cells ;;;

(3)

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8(b)(i) bactericidal ;

(1)

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8(b)(ii) 1. cell wall {weaker /cannot form properly / eq}

;

2. {cell / cell wall} bursts (easily) / eq ;

3. during division /eq ;

max (2)

6BI04_01 1006

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8(b)(iii) 1. reference to antibiotic acting as selective

pressure ;

2. reference to some bacteria resistant (to antibiotic) ;

3. idea that resistant bacteria survive and

{reproduce / pass on resistance / pass on gene / eq};

4. idea that antibiotic no longer effective ;

5. reference to some infections cannot be treated with antibiotics ;

max (2)

6BI04_01 1006

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8(c) 1. idea of bacteria distributed evenly /

description of technique e.g. lawn spreading ;

2. description of method used to apply different antibiotics at known positions e.g. multidisks, wells in agar ;

3. reference to control of antibiotic

concentration ;

4. reference to {sterile / aseptic} technique ;

5. reference to incubation at a suitable temperature ;

6. description of how effect is assessed e.g.

measure {clear area / inhibition zone / eq} ;

7. reference to replication (with same bacterium) ;

8. reference to repetition with different

bacteria ;

max (4)

6BI04_01 1101

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2(a) Feature Bacteria

only Viruses

only Both

bacteria and

viruses Glycogen granules

Nucleic acids

Protein coat (capsid)

1 mark per row ;;;

(3)

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2(b)(i) 1. viruses (and bacteria) involved ; 2. (usually) antibiotics {are only effective

against bacteria / do not affect viruses / eq} ;

3. {other medication / eq} needed to deal

with viruses / eq ;

max (2)

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2(b)(ii) 1. both enrofloxacin and florfenicol named ;

2. idea of {(high) effectiveness / eq} against all three bacteria / eq ;

3. above {80% / 83%} / eq / average above

90% / eq ;

(3)

X

X

X

6BI04_01 1101

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2(b)(iii) 1. idea that antibiotic used is {most effective / eq} (against the known bacterium) ;

2. idea that none of the antibiotics is 100%

effective / some bacteria {survive / eq} ;

3. some bacteria {are resistant / eq} ;

4. idea of resistant strain {develops / prevented} ;

max (3)

6BI04_01 1101

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4(a)(i) Any characteristic symptom of TB e.g. tubercules, bloody sputum, (general)body tissue wastage ;

(1)

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4(a)(ii) D ; (1)

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4(a)(iii)

1. idea of {bacterium / eq} recognised as {non-self / eq} ;

2. reference to labelling of bacteria by B {lymphocytes / cells} ;

3. phagocytosis / phagocytic / phagocyte ;

4. descriptive detail of phagocytosis

(involving {bacterium / eq}) ;

5. reference to formation of vacuole ;

max (3)

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4(a)(iv)

1. {kills / eq} {bacteria / eq} in {stomach / mouth / saliva / gastric juice} ;

2. (by) {(hydrochloric) acid / lysozyme} ;

(2)

6BI04_01 1101

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*4(b)QWC

(QWC – Spelling of technical terms must be correct and the answer must be organised in a logical sequence) Supporting the hypothesis:

1. both HIV and TB infection rates rise and then fall / eq ;

2. both HIV infection and TB infection increase

{from 1990 to 2000 / for the first 10 years} / eq ;

Not supporting the hypothesis:

3. TB infection falls from 2000 onwards but HIV continues to rise (until 2004) / eq ;

4. different {parameters /measures / variables

/ eq} for the two infections / eq ; General points:

5. idea of {more {data / information / eq} is needed / other factors (may be) involved} ;

6. reference to need for statistical {analysis /

test} ;

7. such as correlation {data / test / named example} ;

8. there is no data that {links HIV infection

with TB infection / shows that people with HIV also have TB / shows causal relationship / eq} ;

max (4)

6BI04_01 1101

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8(a) Source of antibodies Form of immunity

D B C A

Note: [accept descriptions instead of letters] 4 correct = 2 marks 2 or 3 correct = 1 mark 0 or 1 correct = 0 marks ;;

(2)

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8(b) 1. (bacterium) is made of many different {polymers / chemicals / eq} / eq ;

2. which can act as antigens / eq ;

3. reference to B {lymphocytes / cells} ;

4. reference to (individual B-lymphocytes)

recognise specific antigens / antibodies are specific / eq ;

5. reference to {activation/ eq} of B-

lymphocytes by T {lymphocytes / cells} ;

6. reference to mitosis (in B-lymphocytes or cells) ;

7. to {form / eq} genetically identical plasma

cells ;

max (4)

6BI04_01 1101

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8(c) 1. specific {antigen / virus / pathogen / bacterium / eq} can be {identified / eq} ;

2. idea of {specific / monoclonal} antibody binds to {specific / only one} antigen ;

3. specific treatment can be given / eq ;

4. avoids unnecessary use of {drugs / treatment} / eq ;

5. more likely to be effective / eq ;

max (3)

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5(a)(i) 1. {competition / eq} for nutrients ;

2. {competition / eq} for space ;

3. {secretion / eq} {chemicals / substances /

lysozyme / eq} OR affects {pH / eq} ;

4. {stimulation / eq} of (skin) immune system / eq ;

(2)

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5(a)(ii) A ;

(1)

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5(b) 1. idea that influenza may allow development of

other diseases e.g. opportunistic infections ;

2. antibiotics will {kill / inhibit growth of / eq} bacteria ;

(2)

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5(c)(i) correct answer 37.2 / 37.17 / 37 (%) gains 2 marks

1. (226 – 142) / 84 ; 2. ÷ 226 to give 37.2 / 37.17 / 37 (%) ;

(2)

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5(c)(ii) 1. yes ; 2. idea that if current rate continues / eq ; 3. idea of achieving lower than the target / eq;

4. credit use of supporting figures ;

(3)

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5(c)(iii) 1. reference to some bacteria {can resist / are

resistant to} antibiotics ;

2. idea of {resistance being genetic / can be passed on} ;

3. reference to MRSA / other named example ;

(2)

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8(a) Statement

True False

HIV infects b-lymphocytes in the human immune system

The genetic material in HIV is a form of RNA

The enzyme, reverse transcriptase, is used by HIV

1 mark each correct row ;;;

(3)

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8(b)(i) 1. change in the {nucleotides / bases} / eq ;

2. in {RNA / DNA} / eq ;

3. which leads to change in the {sequence / eq} of amino acids in (primary structure of) a {polypeptide / protein} / eq ;

(2)

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8(b)(ii) 1. idea that HIV has {many / variety of / new /

eq} {strains / types /antigens / protein coats / eq} (in infected person) ;

2. some strains {are / become} resistant to {an

individual / a specific / a particular / eq} drug / eq ;

3. these would survive if (only one drug used) / eq

;

4. {mixture of drugs / eq } has more chance of getting rid of {all / more} (strains / types / eq) / eq ;

5. reference to drugs used together because of

mutation ;

6. reference to rapid rate of mutation ;

7. reference to rapid rate of {multiplication / eq} of virus ;

(4)

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5(a)

Feature Bacteria

only Viruses only

Both bacteria and viruses

Nucleic acid

Cytoplasm

Protein capsid

1 mark each correct row ;;;

(3)

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5(b)(i)

1. idea of (SCAG is) caused by {a bacterium / bacteria} ;

2. antibiotics {kill / stop reproduction / eq} of

bacteria / are {bactericidal / bacteriostatic} ;

(2)

6BI04_01 1201

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*5(b)(ii) QWC

Spelling of technical terms must be correct and the answer must be organised in a logical sequence

1. as age increases, acid secretion decreases / eq ;

2. as age increases (above 30) , stomach cancer

increase / eq ;

3. as acid secretion decreases (below 120), stomach cancers increases / eq ;

4. idea that the {higher age groups (51+) have low acid and high cancer / lower age groups (up to 30) have high acid and low cancer} ;

5. Idea of {acid / low pH} (in stomach) kills {bacteria

/ Helicobacter} ;

6. reference to development of SCAG {inhibited / prevented / eq} (by low pH / more stomach acid) ;

7. idea of age affects the immune system ;

8. idea that the older you are acid-producing cells are less effective e.g. fewer acid-producing cells / cancer cells replace the acid-producing cells ;

9. idea that {acid / low pH} destroys cancer cells ;

10. idea that mutations (leading to cancer) more likely to occur with age ;

(5)

6BI04_01 1201

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7(a)

C ;

(1)

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7(b)(i)

1. {T helper / CD4 (positive)} (cell / lymphocytes) ; 2. phagocytic cells e.g. macrophages, dendritic cell ;

(2)

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7(b)(ii)

1. reference to (HIV) binds to (CD4) receptors on cell

(surface) ; 2. ref to CD4 (receptors on cells) ; 3. reference to {glycoprotein / gp120} on virus (surface) ;

4. reference to fusion of virus (envelope) with (cell

surface) membrane ; 5. idea of phagocytosis (in macrophage / eq) ;

(3)

6BI04_01 1201

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7(b)(iii)

1. reference to viral RNA ; 2. reference to production of (viral) DNA (using viral RNA

as a copy) ; 3. correct ref to reverse transcriptase ;

4. reference to incorporation of viral DNA into host cell’s

{DNA /genome } / reference to provirus / eq ;

5. correct ref to integrase ;

6. reference to production of {viruses / viral RNA and proteins} / eq ;

7. idea of infection of further (T helper) cells ;

8. reference to destruction of (T helper) cells by T killer

cells OR reference to cell lysis / eq ; 9. reference to lowering of immunity ;(to other diseases ;

10. credit reference to role of T helper cells in immune

response e.g. produce cytokines, activate B cells / killer cells ;

11. death is caused by e.g. opportunistic disease, pneumonia , TB, Kaposi’s sarcoma, cancer, dementia, extreme weight loss, meningitis, toxoplasmosis ;

(6)

6BI04_01 1201

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8(a)

Description True False

B and T cells are formed in the bone marrow

B cells stimulate T cells to produce clones of memory cells

T helper cells produce chemicals that destroy pathogens

B and T cells are able to form clones by mitosis

1 mark each correct row ;;;;

(4)

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8(b)

1. (bacteria are) too small / reference to limitation of {magnification / resolution} ;

2. (bacteria) not stained ; 3. idea of bacteria already {removed / destroyed} e.g.

phagocytosis ; 4. idea that bacteria are not present in the blood e.g.

only a small {region / sample} shown, reference to local infection ;

(2)

6BI04_01 1201

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8(c)(i)

Either: 1. idea of fewer {lymphocytes / eq} ; 2. reference to {lymphocytes / eq} no longer needed / eq

;

3. (as) {antibiotics / drugs} {kill / destroy / eq} bacteria ;

Or: 4. more {lymphocytes / eq} ;

5. idea of clonal expansion (of lymphocytes) / eq ;

6. idea that the antibiotics have not killed all the bacteria

yet ;

(2)

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8(c)(ii)

1. idea that a placebo has no effect ; 2. (therefore there will be) more bacteria / eq ;

3. (therefore there will be) more {lymphocytes / eq} ;

4. (more lymphocytes due to) clonal expansion / eq ;

(2)

6BI04_01 1201

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6(a)

C – plasma cell ; (1)

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6(b)(i)

1. idea of using {virus / PCV2} as vaccine ; 2. which is {modified / attenuated / harmless /

similar / part of / eq} ; 3. idea that the vaccine contains the antigen ;

4. idea of {activation / proliferation} of

(specific) {B cell / T cell / lymphocyte} ;

5. reference to production of (B / T) memory cells ;

6. idea that body now able to produce (specific) antibody {faster / at higher concentration / eq} on another exposure to PCV2 ;

(3)

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6(b)(ii)

1. reference to giving a placebo (to group B) ; 2. idea that all (other) {conditions / factors /

variables} should be {controlled / same as group A} ;

3. stated example e.g. food, temperature of

housing / eq ;

4. reference to group B is a control group ;

5. (so that) only the (effect of) {vaccine / vaccination} is tested / eq ;

6. ref to {valid / validity} ;

(3)

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6(b)(iii)

1. {Greater change / higher / eq} in group A (than B) / eq ;

2. group A rises for first 30 days, group B rises (slightly) for first 20 days / eq ;

3. (this) rise for group A is {faster / greater}

than for group B / eq ;

4. (after the rise) group A falls, group B levels off / eq (until day 140) ;

5. after day 140, group A rises, group B falls /

eq ;

6. credit use of comparative manipulated figures (with units) ;

(3)

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6(b)(iv)

1. idea that (antibodies present at birth as)

both groups received antibodies from mother ;

2. via {placenta / blood / milk / breast feeding} ;

3. reference to passive immunity ;

4. group A concentration falls because {piglets

not infected by (PCV2) virus/ antibodies excreted / passive immunity is short term} /eq ;

5. group B concentration rises because {PCV2 / virus} present / eq ;

(3)