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In England and Wales, between 1992 and 2001, samples of blood were taken from patients infected with the bacterium Staphylococcus aureus.
(i) Suggest explanations for the positive correlation in the data in the graph. (3)
greater use / overuse / over prescription, of methicillin ✓
not completing course (of methicillin) ✓
idea of: use (of methicillin) in farming ✓
natural selection of MRSA ✓
idea that: large % increase (in a short time) due to fast generation time ✓
(ii) Staphylococcus aureus is the binomial name for a species of bacterium.
State one advantage of referring to Staphylococcus aureus in this way. (1)
idea of: universal language ✓
shows evolutionary relationship between species (at the genus level) ✓
Complete the table below by writing the correct answers in the empty boxes.
What feature of a pathogen such as Mycobacterium tuberculosis could be altered by a mutation, making a vaccine ineffective? (1)
(shape of), proteins / glycoproteins / glycocalyx / antigens of the plasma / cell surface, membrane (1)
(i) Outline the processes that lead to the production of antibodies against an unfamiliar bacterium. (3)
B cells / lymphocytes, have, antigen receptor / carry antibody, on surface, specific / complementary to, only one antigen (1)
selected / activated, B cell, proliferates / clones / divides by mitosis (1)
forms / differentiates into, plasma / effector, cells (1)
which secrete antibodies specific / complementary, to antigen (1)
(ii) Explain how helper T cells act to speed up these processes. (2)
(helper T cells) stimulated by antigen presenting cells (1)
release, cytokines / interleukin 2 (1)
stimulate B-cell, proliferation / mitosis / clonal expansion (1)
(i) It takes time for an effective vaccine to be prepared in quantity for a new strain of bacterium.
List two vulnerable groups of people for whom you would advise doctors to prescribe antibiotics although they are not yet showing symptoms of the new disease.(2)
babies / infants (1)
elderly / infirm (1)
immuno-compromised / on immunosuppressant drugs / HIV positive (1)
Discuss the implications of the over-use of antibiotics when people do not show symptoms.
two from
(antibiotic is) selective pressure (1)
(bacterial) gene pool / AW, has variation (1)
(only) some bacteria have resistance / some bacteria are more resistant than others (1)
two from
when exposed (to antibiotic) most-resistant survive (1)
surviving bacteria continue to reproduce to make a resistant population (1)
idea that over many generations there is an increase in proportion of resistant bacteria (under continued antibiotic pressure) (1)
antibiotic becomes ineffective / new antibiotic needed (1)
(i) What is the role of an opsonin during this process?(1)
(ii) Other than having specific receptors, describe one way in which the structure of the neutrophil is specialised. (1)
i) (opsonin) binds to antigen on pathogen and, assists binding / binds, to phagocyte
ii) any one: well-developed cytoskeleton (1)
many lysosomes (1)
many mitochondria (1)
lobed nucleus (1)
When their bark is damaged, trees in the genus Boswellia release the aromatic resin frankincense which soon hardens to cover the wound.
(i) Suggest two ways in which frankincense contributes to defending the tree from pathogens
prevents pathogens entering wound (1)
aromatic compound is antibacterial (1)
* There are a number of different strains of the Clostridium botulinum bacterium. Different strains produce immunologically distinct forms of the toxin.
Explain why the toxins produced by the different strains are described as being ‘immunologically distinct’ and how they will be dealt with by the immune system. (6)
immunologically distinct
toxins produced by each strain will be (slightly) different
each (botulinum) toxin will have different, 3D shape / amino acid sequence / DNA nucleotide coding sequence
toxin, acts as / is, antigen immune response determined by shape of antigen
different compounds will have different shapes
immune system
antigen presenting cells ingest antigen and display antigen on their surfaces
interaction between APCs and T-helper cells causes production of interleukins
B cells activated by T-helper cells clonal selection and clonal expansion
B cells differentiate into plasma cells plasma cells produce, antibodies / immunoglobulins
antibodies bind to and neutralise toxins by protein synthesis
A patient has been diagnosed with an autoimmune disease. Which of the treatments, A to D, is most likely to relieve the symptoms?
A a course of antibiotics
B a vaccination containing antibodies
C drugs to suppress the immune system
D surgery to remove the affected parts
C
The graphs below show the concentration of antibodies in the blood of four people after a first natural exposure to an antigen.
One of the people had been vaccinated against this antigen previously. Which of the graphs, A to D, represents the person who had been vaccinated?
B
The following passage describes the mode of action of a phagocyte. Complete the passage using the most appropriate words or phrases
Receptors on the cell membrane of a phagocyte recognise antibody molecules known as _ _ _ _ _ _ _ _ _ _ _ _ _ _ , which are bound to pathogens and enhance phagocytosis. Once engulfed by a phagocyte, a pathogen is contained in a vacuole called a _ _ _ _ _ _ _ _ _ _ _ _ _ _ . Organelles called _ _ _ _ _ _ _ _ _ _ _ _ _ _ produce enzymes that digest the pathogen.
opsonins ✓
phagosome ✓
lysosomes ✓
(i) Which of the two images, A or B, shows a non-specific immune response? Explain your answer.
A because nuclei (of white blood cells) are lobed ✓
The photograph below shows a blood smear.
List the cells that are visible in the smear. (2)
erythrocytes
neutrophils
(a) The potato plant, Solanum tuberosum, is a staple food plant in many parts of the world. Potatoes are susceptible to infection by a pathogen called Phytophthora infestans, which causes a disease known as potato late blight. The most visible sign of the disease is a brown discolouration of the leaves. Some varieties of potato are resistant to infection by P. infestans.
State two ways in which an individual S. tuberosum plant could respond to infection by P. infestans (2)
production / AW of, callose
release / production, of (named / toxic) chemical
leaf drop / abscission
necrosis
Which of the following antibodies increase(s) the phagocytosis of pathogens?
1 opsonins
2 agglutinins
3 anti-toxins
only 1 and 2
Agammaglobulinemia and Vici syndrome are both genetic diseases. Agammaglobulinemia results in a lack of mature B lymphocytes in a person’s blood.
(i) Suggest and explain one symptom of agammaglobulinemia.
idea of greater susceptibility to, infection / pathogens ✓
e.g. immune deficiency/ slower immune response/weakened immune system / longer time to recover from infection IGNORE ref to illness / disease / immunological memory
no / fewer, plasma cells / effector cells / antibodies ✓
Which of the following statements, A to D, could explain the data shown for 1999-2000?
A the malarial parasite had developed resistance to insecticides
B the vector had developed resistance to antibiotics
C the malarial parasite had developed resistance to antiviral drugs
D the vector had developed resistance to insecticides
D
A student wrote the following passage in an essay on the immune system. Immunisation programmes involve injecting individuals with a small amount of the safe antibody, known as a vaccine. In the UK, babies are given routine vaccinations against a range of infectious diseases including diphtheria and measles. These injections provide a form of natural passive immunity that may last a year, a few years or a lifetime. State three errors that the student has made in this passage.
antibodies not used / should say antigens used ✓
not natural (immunity) / should say artificial (immunity)
✓ not passive (immunity) / should say active (immunity) ✓
Sweet potato cells have a mechanism that recognises and destroys incorrectly formed mRNA or non-functional mRNA.
(i) The nucleic acid in potyviruses is RNA. Suggest why this mechanism in sweet potato cells is able to counteract infection by a potyvirus (2)
any two from: 1 virus / foreign, RNA recognised (as incorrect) ✓
2 virus / foreign, RNA / genome, cut / destroyed ✓
3 virus, replication / reproduction, stopped ✓
faulty / incorrect, (m) RNA destroyed ✓
faulty / wrong, proteins not made or prevents errors in protein synthesis ✓
* The specific immune response involves B and T lymphocytes. There is variation in specific immune responses between individual animals.
Variation between immune responses can be influenced by genes and the environment. Using examples, explain how both genes and environment can cause animals to vary in their specific immune responses. (6)
Fig. 4.1 shows one person’s immune response to the influenza virus when they were first infected and when they were infected two years later by a new, mutated strain of the virus.
The influenza virus has many antigens to which the immune system can respond. Fig. 4.1 shows the response to four of these antigens (A–D).
Explain the differences in the person’s initial immune response to the influenza virus with their immune response two years later
DNL-Fab3, shown in Fig. 4.2, is an example of a synthetic antibody.
State two conclusions that can be drawn from Fig. 4.2 about the differences between the way DNL-Fab3 functions and the functioning of normal antibodies. (2)
Vancomycin is an antibiotic that has been used to treat bacterial infections for many decades. Several strains of bacteria have evolved resistance to vancomycin.
Oritavancin is an antibiotic with a similar structure to vancomycin.
Use the data in Table 4.2 to evaluate the advantages and disadvantages of using oritavancin rather than vancomycin as an antibiotic.(2)
Phagocytosis involves cytokines and opsonins. State the role of cytokines and opsonins in phagocytosis.(2)
Which of the blood components, labelled A to D, shows a lymphocyte?
D
Complete the following sequence to outline how a vaccine gives an individual immunity. The first two steps have been completed for you.
Step 1: A vaccine is produced that is a safe form of an antigen.
Step 2: A small amount of vaccine is injected into blood of the individual to be vaccinated.
Step 3:
Step 4:
Step 5: (3)
step 3
antigen presentation / antigen binds to specific, B / T, lymphocyte / cell ✓
steps 3 or 4
clonal selection / clonal expansion / plasma cells produced / produce antibodies primary immune response ✓
step 5
ref. memory cells / secondary immune response ✓
Some people are immune to malaria. They produce a specific type of antibody. One way in which antibodies defend the body is by acting as agglutinins. Outline the action of agglutinins. (2)
clump / aggregate / join, pathogens ✓
stops pathogens, moving / reproducing ✓
(helps) phagocytes then engulf (multiple / clumped) pathogens / phagocytosis of (clumped) pathogens ✓
Explain what is meant by an autoimmune disease and suggest why members of the same family can be sufferers of autoimmune diseases. (2)
idea that immune system, attacks / damages, own / self, cells / tissue / antigens ✓ plus any one of: genetic / passed down in genes / linked to certain alleles / ref. DNA ✓
Plants such as the soybean have a number of defence strategies to prevent infection by pathogens. Which of the following strategies is a chemical defence against pathogen infection?
A callose deposits at sieve tube ends that prevent pathogen movement in phloem
B hydrolytic enzymes such as chitinase found between cells
C stomata can be closed by guard cells if pathogens are detected
D cell walls can be thickened by lignin, making cell entry very difficult for pathogens
B
Haemoglobin is found in erythrocytes. Unlike other vertebrates, the mature erythrocytes of mammals lack nuclei and other membrane-bound organelles.
(i) Explain one advantage and one disadvantage of the lack of nuclei and other membranebound organelles to mammalian erythrocytes. (2)
advantages
A1 more space for / can contain more / can carry more, haemoglobin / oxygen ✔
A2 can squeeze through capillaries easily ✔
disadvantages
D1 limited life span / cannot divide / cannot reproduce / cannot undergo mitosis ✔
D2 no, protein synthesis / repair ✔
(ii) Viruses do not use erythrocytes as host cells, whereas the malarial pathogen Plasmodium spends part of its life cycle inside erythrocytes. Suggest why (2)
virus is unable to / cannot, replicate / reproduce, on its own / outside a host cell or virus requires host cell, machinery / DNA / RER / ribosomes, for protein synthesis
for Plasmodium to use as a source of food (for, growth / reproduction) ✔
Explain why erythrocytes do not make use of any of the oxygen that they are transporting. (2)
1 oxygen is bound to haemoglobin (while being transported) ✔
2 lack mitochondria ✔
3 (therefore) no aerobic respiration ✔
Antibodies are important biological molecules. Describe how the structure of antibodies allows them to perform their function.
2 light chains and 2 heavy chains / 4 polypeptide chains;
variable region allows, binding / attachment, to antigen;
two variable regions allow binding of more than one (of the same) antigen;
variable region on different antibodies allows specificity to different antigens;
constant region allows, recognition by / attachment to / binding to, (named) phagocytes;
hinge (region) allows flexibility; 7 disulfide, bonds / bridges, hold, polypeptides / light and heavy chains, together;
) Fig. 4 shows the concentration of antibodies in a patient’s bloodstream following an influenza (flu) vaccination, and then a subsequent infection with the influenza virus. Fig. 4 Describe where the primary and secondary immune responses are taking place on Fig. 4 and explain the differences between the two processes.
L primary, (just) after vaccination / when the person is vaccinated and secondary, (just) after infection / when the person is infected ✓ primary P slow(er) / delayed, response because of, clonal selection / clonal expansion / production of antibodies ✓ Secondary S quick(er) response / shorter lag time / more antibodies produced, because of, memory cells / immunological memory ✓
