HUMAN AND SOCIAL BIOLOGY
GCE Ordinary Level
Paper 5096/01
Theory
General comments
The paper generated a wide range of marks. Very few candidates failed to answer 3 questions in Section B
and fewer than usual answered all 5, so examination technique is improving. In Section A, genetics proved
once again to be a problem area, as did the calculations and the diagram-completion question. In Section
B, weaker candidates seemed to select their questions on the basis of their first sections, so that they were
often unable to answer later and more challenging sections when they reached them. It is always a good
idea to read the whole text before starting a question. Further, when a question asks for two examples,
giving a list of four or five possible answers will not increase the chances of scoring, since only the first two
are marked.
Comments on specific questions
Section A
Question 1
This question required five organisms to be identified from a list of six, using a key. Although the question
used features commonly attributed to these organisms in the syllabus, the use of the key format caused
problems for many. Keys are a useful way of testing the application of knowledge and could, perhaps, be
practised more, so that this format is more familiar to the candidates. The answers were A-virus, Bbacterium, C-protozoan, D-hookworm and E-bloodfluke. Hookworm was identified correctly most often in
this list.
Question 2
This question dealt with methods by which materials move in and out of cells.
(a)
The answers were osmosis, active transport, phagocytosis and diffusion. Phagocytosis was
usually recognised correctly from the description given, but diffusion and active transport were
often confused.
(b)
The methods not requiring energy were osmosis and diffusion.
Question 3
This question was generally well done, with most candidates able to name the liver and the pancreas. A
good proportion could also identify bile and lipase as the two solutions. Naming two fat-soluble vitamins
proved more difficult and many resorted to guesses here. Suitable answers were A, D, E or K.
Question 4
(a)
This part required the completion of a diagram of a spinal reflex arc by drawing in the sensory and
motor neurones. This was poorly done by the majority, although the basic diagram is well known.
The sensory neurone should run from the receptor into the spinal nerve, up the dorsal root and
synapse to the relay neurone shown there. The cell body should be shown in the dorsal root
ganglion. The motor neurone runs from its cell body down the ventral root and spinal nerve to the
muscle.
(b)
Most candidates could name the relay or intermediate neurone.
http://www.xtremepapers.net
1
(c)
Few candidates could state that the transmission across the synapse was chemical.
(d)
Most candidates knew at least one effect of alcohol on the behaviour of an individual.
Question 5
(a)
This part proved difficult for many candidates, since they failed to read the question stem and
appreciate that the clear areas represented no bacteria present. The largest effect was seen with
B, the disinfectant.
(b)
This is toxic or would damage body tissues, so could not be used internally.
(c)
It was clear from the answers that the concept of a control in biological experiments is not
appreciated. It is simply a repeat of the original experiment with one factor changed to see if there
is any difference in the result. A suitable control here would be to repeat the experiment but
substitute plain discs or discs with water to show it is the chemicals which produce the effect and
not the paper discs alone.
(d)
Most candidates could identify penicillin as an antibiotic.
Question 6
This question concerned the inheritance of eye colour.
(a)
P is Bb, since although brown eyed she has a blue eyed son T. V is also Bb, since his father is
blue eyed and so contributes a recessive allele b to V, yet V is brown eyed.
(b)
Only S could be homozygous, he is brown eyed and with only one child U (who is also brown eyed)
there is not enough evidence to say he is not BB.
Question 7
Parts (a) and (b) required some calculations to be made using figures from the table.
(a)
The difference in carbon dioxide concentrations is 100 times. (0.04 v 4.0).
(b)
The oxygen-extraction efficiency is 20%; 4/20 x 100=20%.
Question 8
This question produced some good scores. This is an area that is well understood by most candidates. The
virus causing AIDS is HIV.
Haemophiliacs need transfusions of blood or factor 8. If these transfusions come from infected sources the
recipient may get AIDS, so infected blood transfusions was the answer. The body cell affected is the
lymphocyte or T-helper lymphocyte or even the white blood cell, but not phagocyte.
Section B
Question 9
This question was a popular choice. Many scored well on part (a), stating how plants used carbon dioxide.
Some confusions with respiration occurred, predictably. Calcium is needed for clotting and muscle
contraction as well as for hardening bones and teeth.
The hepatic portal vein was often identified correctly as the vessel carrying food to the liver. The fates of
glucose and amino acids in the liver produced mixed quality answers.
Glucose was the better understood, but the usual confusions between glucagon and glycogen spoiled some
responses. Many answers referred correctly to amino acids being deaminated, but failed to score more by
not saying what happened next: the ammonia is converted to urea; the fatty acid residue is respired or stored
as glycogen or fat. Amino acids cannot be stored but may be built into proteins in the liver or changed into
other amino acids.
2
Question 10
This question was less popular. In part (b), candidates often only made one point, when 3 marks were
available. The bloods are kept separate because not only are their oxygen levels very different as most
candidates said, but so too are their carbon dioxide levels and their pressures. Each of these differences
could be related to the different circulations they serve. Thus, the high pressure of the left ventricle would
burst the lung capillaries; the lower pressure of the right would be insufficient to supply the body circulation.
Blood pressure is high at the glomerulus to promote filtration; to force small molecules into the capsule. If
not filtration would slow up, so that solutes would stay in the blood as would water, leading to oedema.
In part (d), the pacemaker is found in the wall of the right atrium. Its role is to initiate contraction waves in
the muscle of the two atria, and then to stimulate the ventricular muscle. One group treated this as an
artificial pacemaker installed in a failing heart.
The effects of carbon monoxide on red blood cells were not well understood. Carbon monoxide has a very
high affinity for haemoglobin, so combines more readily than oxygen; the reaction is irreversible and so
reduces the amount of oxygen the blood can carry. Such damaged cells are removed from the blood leading
to a lower red cell count.
Question 11
This question, on the skeleton, was popular but carried a sting in its tail with 6 marks offered for a description
of how muscles move food.
(a)(b)
These parts were usually well done.
(c)
The roles of the cartilages were usually overlooked, as were the close fit of the bone ends. Most
limited themselves to a mention of synovial fluid and lubrication.
Bone is living since it respires, grows and is composed partly of cells. This is advantageous since
it grows as we grow, can repair itself and is a dynamic system responding to stresses as we
exercise particular muscle-groups regularly.
(d)
The last section was the worst done, as a rule, with many contenting themselves with a brief
reference to peristalsis. The description should have included references to contractions of the
circular muscle(behind the bolus); relaxation of the circular muscle(in front of the bolus);
contractions of the longitudinal muscle in antagonistic fashion; that these actions were rhythmic;
the muscles acting against the gut contents.
Question 12
This question attracted a lot of answers but, in fact, required fairly detailed knowledge of the life cycle of the
mosquito, linked to feeding and to large-scale control methods of each stage. Confusion over the stages
was often evident from the start.
(a)
The egg is supplied with food in the yolk. The larva feeds on algaeplanktonbacteria; in water;
collecting these by its mouth-brushes, a form of filter-feeding. The pupa uses food stored inside its
case. The adult male feeds on plant juices sucked from the leaf-veins. The female supplements
her diet with blood before laying each batch of eggs using saliva as an anticoagulent.
(b)
This part asked for a large-scale method to control each stage, so references to emptying cans or
flower-vases of their water were not allowed, nor were nets or coils to control the adult. The
question asked for an explanation of each method chosen. This was frequently overlooked and it
was not always clear to which stage the method referred. Thus B, thuringiensis is an excellent
method for larvae but not for pupae. For adults insecticides, especially residual insecticides
sprayed inside houses to kill them as they settle prior to feeding would score well, whereas the
single word insecticide scores nothing.
(c)
Most candidates got 2 signs at least, but there was the usual confusion with symptoms. Feeling
hot is a symptom, not a sign. Few mentioned the fact that the signs occur at regular intervals.
(d)
The net is to prevent the mosquito from becoming infected by biting the patient, as the majority of
the answers suggested.
3
Question 13
This question was often chosen, probably for its easy opening section but, as with Question 11, more
difficult sections awaited the unwary.
(a)
This part was usually answered well, although some failed to state how their pollutants affected the
environment.
(b)
Most answers to this section lacked detail as to what was filtered and how this was achieved.
Sedimentation and filtration were often confused.
Further treatment is required, since the water may still contain bacteria, some of which may be
pathogenic. Most suggested boiling or chlorination correctly as suitable methods but quite a lot
thought fluoridation applied here too.
(c)
This part, on the uses of water, was the weakest section for all but a few candidates. Most talked
of water only as a transport medium and listed all the substances it carried or referred to washing
food or clothes when the question said the uses of water in the body. Water is also a reagent (in
hydrolysis reactions); a component of cytoplasm and thus of cells and tissues. It is a large part of
blood, lymph and tissue fluid as well as such liquids as tears, synovial fluid, semen, mucus etc. It
distributes heat around the body and acts as a coolant when it evaporates as sweat.
Paper 5096/02
Multiple Choice
Question
Number
Key
Question
Number
Key
1
C
21
D
2
D
22
D
3
D
23
D
4
A
24
B
5
C
25
C
6
D
26
B
7
B
27
C
8
D
28
D
9
A
29
A
10
B
30
B
11
B
31
D
12
B
32
C
13
C
33
D
14
B
34
C
15
C
35
D
16
C
36
D
17
D
37
B
18
D
38
D
19
C
39
A
20
A
40
A
4
General comments
A standard deviation of 5.505 was obtained for this paper. The mean score was 17.096 (42.7%) which is
lower than last year. However, with the low entry number of candidates this year, some caution is needed in
interpreting the statistics. In particular, the low point biserial shown by Questions 6, 12, 29, 34 and 38 is
somewhat unusual because these questions directly test only knowledge of one stated syllabus objective.
Where understanding two syllabus objectives for the same question was needed, difficulty was encountered
in applying the knowledge as shown by Questions 13, 16 and 20. The hygiene and health questions were
most competently answered as shown by Questions 7, 8, 9, 25, 31 and 33. Questions 7, 9, and 33
appeared too easy, but it is pleasing that such relevant socially significant topics are well understood.
Comments on specific questions
Question 3
The positive distractor but good discrimination, indicates that the less able candidates thought lymphocytes
are a tissue. See also Question 12, where it appears that study of the parts of the blood needs to be more
thorough.
Question 6
The syllabus objective which states, ‘proteins: used for growth and repair and as a component of
haemoglobin’, was directly tested. Most candidates, instead of selecting haemoglobin, answered that
proteins are needed to act as an energy store. While protein may act as an energy store, it is not needed for
that purpose.
Question 7
This was surprisingly well answered considering that a fairly complex table had to be interpreted to deduce
which nutrients would keep bones and teeth healthy.
Question 12
Candidates have to know that the fluid part of blood is plasma and that it transports carbon dioxide. This is
directly from syllabus objective 5(c), so the low facility and point biserial are difficult to explain. Perhaps fluid
was not considered to be plasma.
Question 13
Most unusually, the fewest candidates chose the correct answer. The part played by muscle contraction in
returning blood to the heart must have been neglected. This is essential knowledge to understand the
syllabus section on circulation and how veins function.
Question 15
The lack of understanding of how the pressure changes in the lungs during breathing is evident again here,
as it has also been shown in previous years’ papers. The balloon and bell jar experiment is recommended to
help teach this important concept.
Question 16
The question combines syllabus section 1(k), diffusion, with 6(e), gaseous exchange in the alveoli. The need
to invest knowledge with understanding is important, particularly when the transfer of knowledge between
sections, studied at different times, is necessary.
Question 17
The positive distractor was most likely caused by the inability to read the graphs. The distractor option A
shows fewer babies with a low birth mass born to mothers who smoke during pregnancy, while the key
response D shows more births with low mass.
5
Question 20
Again, the fewest candidates chose the correct answer. In this case, identifying the kidney cortex from a
photomicrograph, or the lack of knowledge where filtration takes place, caused the difficulty.
Question 35
The high positive distractor indicates that candidates are not clear about the difference between active and
passive immunity, particularly in relation to breast milk.
Question 38
It appears that this syllabus section may have been neglected, possibly because the syllabus provides an
option to study either the trickle filter or the aeration tank method. Both were given in this question, but the
answers showed a very poor understanding of where aerobic bacteria are active.
6