AJ L3 CHD Qs & MS

Q1. Diagram 1 shows a section through the heart.

Diagram 1

 
(a)     Use words from the box to label parts A, B, C and D.
 
artery atrium capillary platelet vein ventricle
(4)
(b)     Diagram 2 shows one treatment for a diseased coronary artery.
Diagram 2

 
© Nucleus Medical Art/Visuals Unlimited/Corbis
(i)       Name the treatment shown in Diagram 2.
______________________________________________________________
(1)
(ii)     Explain how the treatment works.
______________________________________________________________
______________________________________________________________
______________________________________________________________

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 ______________________________________________________________
(2)
(Total 7 marks)
Q2.
This question is about the circulatory system.
(a)  Draw one line from each blood component to its function.
 
Blood Component   Function
 
Destroys
   
microorganisms
 
Helps the blood
Platelet  
to clot
 
Transports glucose
Red blood cell  
around the body
 
Transports oxygen
White blood cell  
around the body
 
Transports
   
urea
(3)
(b)  The diagram below shows cross sections of the three main types of blood vessel
found in the human body. Each blood vessel is drawn to the scale shown.

 
Which blood vessel has the smallest diameter?
Tick one box.

 
(1)
(c)  Which blood vessel in the figure above is an artery?
Give one reason for your answer.
Blood vessel: ___________
Reason: ____________________________________________________________
___________________________________________________________________
(2)
Table 1 gives information about the blood flow in two people.
Table 1
 
Blood flow through
the coronary arteries
Person
in
cm 3 / minute
A – does not have coronary heart disease 250
B – has coronary heart disease 155
(d)  Calculate the difference in blood flow between person A and person B.

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 ___________________________________________________________________
___________________________________________________________________
Difference = ______________________________ cm 3 / minute
(1)
(e)  Suggest why blood flow through the coronary arteries is lower in people with
coronary heart disease.
___________________________________________________________________
___________________________________________________________________
(1)
(f)   Calculate the volume of blood flowing through the coronary arteries of person A in 1
hour.
Give your answer in dm 3.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Volume of blood in 1 hour = ____________________ dm 3
(2)
Coronary heart disease can be treated by:
•   inserting a stent
•   using a Coronary Artery Bypass Graft (CABG).
Table 2 gives information about each method.
Table 2
 
  Stent CABG
The patient is not awake
The patient is awake during the procedure.
during the procedure. The chest is cut open.
A small cut is made in the A section of blood vessel
skin. from the arm or leg is
Procedure
A wire mesh is inserted removed. It is used to
into the coronary artery via create a new channel for
a blood vessel in the arm blood to bypass the
or leg. blockage in the coronary
artery.
When
When only one blockage is When multiple blockages
procedure is
present are present
recommended
Time spent in
hospital after 2-3 hours at least 7 days
procedure
Recovery time
7 days 12 weeks
after procedure
Risk of heart
attack during 1% 2%
procedure
Chance of
failure within 40% 5%
one year
(g)  Give two advantages of using a stent instead of CABG.
1. _________________________________________________________________
___________________________________________________________________
2. _________________________________________________________________
___________________________________________________________________
(2)
(h)  Give two advantages of using CABG instead of a stent.

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1. _________________________________________________________________
___________________________________________________________________
2. _________________________________________________________________
___________________________________________________________________
(2)
(Total 14 marks)

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Mark schemes

Q1.
(a)     A artery
allow aorta
1

B ventricle
ignore references to left and right
1

C atrium
ignore references to left and right
allow atria
1

D vein
allow vena cava
1

(b)     (i)      stent
1

(ii)     keeps (artery) open

1

so (more) blood can flow through

allow blood can flow (more) easily
ignore ref to blood clots
1
[7]

Q2.
(a)

additional line from a blood component negates

the mark for that component
1
1
1

(b)  C
1

(c)  (vessel) B

thick walls or thick muscle / elastic tissue

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 do not accept ref to ‘cell walls’
1

or
lumen is small / narrow
allow description of ‘lumen’
1

(d)  95
1

(e)  (because coronary) arteries / they are narrower

allow (because the coronary) arteries are
blocked / clogged (with fat)
1

(f)   250 × 60 (= 15 000)

or
15 000
allow 0.25 × 60
1

15

an incorrect conversion to dm3 in calculation

does not negate marking point 1
1
an answer of 15 scores 2 marks

(g)  any two from:

•   no need to stay as long in hospital (after procedure) or can go home
sooner / same day
allow only need to stay 2–3 hours in hospital
(after procedure)
allow less scarring
allow less chance of infection
allow only a small cut needed

•   not as / less invasive or no need for a major operation or no need for

general anaesthetic
•   shorter recovery time or can get back to normal lifestyle quicker or less
time needed off work
allow only 7 days recovery

•   lower risk of a heart attack (during procedure)

ignore reference to cost
ignore idea that it takes less time overall
2

(h)  lower chance of failure (within one year)

allow only a 5% chance of failure
1

only need one operation to treat multiple blockages or can treat multiple

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blockages at one time
ignore ref to anaesthetic or CABG being a long-
term treatment
1
[14]

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Examiner reports

Q1.
(a)     Most students correctly labelled the heart, although there were a significant minority
that mixed up the atrium and ventricle.

(b)     (i)      A significant number of students did not attempt to answer this question and
only a third gained credit. There was a wide range of incorrect answers but
mainly ones in which students tried to give a term that could describe what
they could see in the diagram.

(ii)     Students performed better on this part of the question than in the naming of
the treatment and well over a third of students gained full marks. Of the
students who gained full marks there were a significant number who were
describing the treatment accurately and clearly. However, a worrying minority
thought that the stent was unblocking the artery by pushing the fat /
cholesterol out of the artery and a number were confusing the treatment with
dialysis, pacemakers, gastric bands or valve replacement.

Q2.
(a)  Although 59% of students achieved all three marks here, once an error had been
made it was likely that further errors would be made, so the award of one or two
marks only was much less common.

A small number of students drew multiple lines from each blood component, despite
the instruction.

(b)  45% of students correctly identified C as the vessel with the smallest diameter. Very
many chose B, perhaps believing the question referred to lumen diameter and
missing the references to scale.

(c)  The choice of blood vessel and the reason for this were marked independently but,
commonly, students either scored both marks (37%) or none (45%).

Incorrect understanding of scale and magnification led some to select C as ‘×7500’

made it seem larger than the others. The choice of A tended to be linked to the
bigger lumen being able to accommodate the ‘large amounts of blood’ carried by
arteries.

The reason for B being the correct choice hinged on either the small(er) lumen (or
appropriate synonym) or the thick(er) walls. Students more frequently referred to the
wall but answers that were too vague e.g. ‘it is thickest’ or ‘because of the depth of
muscle and elastic tissue’, without qualification of what was ‘thickest’ or ‘how deep’
the tissue was, could not be given credit.

Very few students referred to the labelled elastic or muscle tissues. Some students
referred to ‘cell walls’ which is clearly incorrect.

(d)  91% of students were able to complete this calculation correctly. Incorrect attempts
usually used inappropriate calculations, such as adding the values or determining
the mean of the two figures.

(e)  The inclusion of ‘lower’ in the question showed that some clear comparative
difference was required to achieve the mark. An answer which just stated that they

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 were narrow or thin did not match this as it could apply to all coronary arteries.

If students referred to the arteries being blocked this was accepted unless qualified
incorrectly. Some answers were too vague to credit, such as ‘they are weaker’ or
‘it’s harder for blood to flow through them’

(f)  A correct answer of 15 here gained both marks, provided that working, if given, was
appropriate. The majority of students realised that the figure for blood flow per
minute in Table 1 needed to be multiplied by 60 to get the volume in 1 hour. If this
was evident, then they were credited for working even if the final answer was
incorrect.

Many students only gained one mark here for 15 000. Students either forgot to
convert this to dm3 or converted it incorrectly.

(g)  This question was quite straightforward for students who compared the two
procedures. This entailed the use of directly comparative descriptors, e.g. shorter, or
by implication by using appropriate conjunctions, e.g. however. Answers which were
not specific enough such as ‘it is safer’, or ‘it is quicker’ did not gain credit.

Those students who inferred that there was a greater risk of a heart attack at a later
stage rather than during the operation had misinterpreted the information in the
table. Similarly, those who said that the procedure only lasted 2−3 hours gained no
credit as they had not been given any information about the length of time of the
operation.

Very occasionally a student misread this question (and the subsequent one) and
gave, instead, the advantages of CABG over the use of a stent.

(h)  Provided the answers were comparative, 82% of students picked up the first
marking point here. The second idea was more difficult. It was quite common to just
see reference to it being better for multiple blockages but this was insufficient. To
gain the mark a student had to appreciate that only one operation was required to
treat these multiple blockages when CABG was used.

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