9700_w16_qp_23
A paper of Biology, 9700
Questions:
6
Year:
2016
Paper:
2
Variant:
3
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1
Table 1.1 shows some features of four biological molecules that are all polymers. Complete Table 1.1 by using a tick (3) to indicate the features that apply to each polymer. Table 1.1 feature amylopectin cellulose RNA polypeptide synthesised from amino acid monomers contains glycosidic bonds polymer is branched contains nitrogen can be found in both animal and plant cells is a simple diagram of a phospholipid molecule. Explain how the structure of a phospholipid molecule makes it suitable for its function in cell membranes. You may label and annotate as part of your answer. State two components of a cell surface membrane other than phospholipid molecules and describe their function. component 1 function component 2 function
2. Biological molecules  →  2.2. Carbohydrates and lipids
4. Cell membranes and transport  →  4.1. Fluid mosaic membranes
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2
Explain how enzymes lower the activation energy needed to allow reactions to proceed. Folic acid is a molecule used by all cells for growth. Bacteria cannot absorb folic acid from their surroundings. Bacteria use an enzyme to make a molecule called PABA. PABA is used to make folic acid. An investigation was carried out to determine the effect on the production of PABA when the concentration of an enzyme inhibitor is increased. Four different concentrations (1 µM to 30 µM) of the inhibitor were used, together with a control with no inhibitor. The concentration of PABA produced in each reaction mixture was determined at 10 minute intervals. The results are shown in . time / min concentration of PABA produced / μM concentrations of inhibitor no inhibitor 1 μM 3 μM 10 μM 30 μM Use to describe the results of the investigation. Outline an experiment that could be carried out to determine whether the inhibitor of the enzyme that catalyses the reaction to produce PABA is competitive or non-competitive. Folic acid from the diet is able to enter human cells, but is not able to cross bacterial cell walls. Human cells do not have an enzyme to make PABA. Suggest why the inhibitor of this enzyme could be used as a drug to treat bacterial infections in humans. Suggest why there are few drugs that have any effect on viruses. The search for new antibiotics is important because there are many strains of bacteria that are resistant to antibiotics. Suggest two ways to reduce the spread of antibiotic resistance.
10. Infectious diseases  →  10.2. Antibiotics
3. Enzymes  →  3.2. Factors that affect enzyme action
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5
In an investigation, the volume of oxygen that combined with haemoglobin at different partial pressures of oxygen was determined. The results are shown in . volume of oxygen combined with haemoglobin / cm3 100 cm–3 blood partial pressure of oxygen / kPa The partial pressure of oxygen in the alveoli is 13.3 kPa. At this partial pressure of oxygen the total volume of oxygen that is carried by 100 cm3 blood is 19.78 cm3 at pH 7.4 and 37 °C. The volume of oxygen that combines with haemoglobin at 13.3 kPa is 19.48 cm3 100 cm–3 blood. Calculate the percentage of oxygen that is combined with haemoglobin in 100 cm3 blood. answer % Suggest how the oxygen that is not combined with haemoglobin is transported in the blood. Explain why a long-term smoker would have a lower volume of oxygen combined with haemoglobin in the alveoli at 13.3 kPa. Describe the role of carbonic anhydrase in the transport of carbon dioxide. The investigation was repeated in the presence of carbon dioxide. The volumes of oxygen combined with haemoglobin at partial pressures of oxygen below 8.0 kPa were less than shown in . Name this effect and explain the advantage of this decrease at partial pressures of oxygen below 8.0 kPa. name advantage
8. Transport in mammals  →  8.2. Transport of oxygen and carbon dioxide
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6
Measles is a highly infectious disease. Name the pathogen that causes measles. The number of cases of measles is reported to the World Health Organization (WHO) by countries throughout the world so that global data are collected. shows the global data collected between January 2008 and December 2012. Jan 2008 Mar May Jul Sep Nov Jan 2009 Mar May Jul Sep Nov Jan 2010 Mar May Jul Sep Nov Jan 2011 Mar May Jul Sep Nov Jan 2012 Mar May Jul Sep Nov 10 000 15 000 20 000 25 000 number of cases Key Africa Rest of the world 30 000 35 000 40 000 45 000 Use the data in to describe the pattern shown in the number of cases of measles reported to the WHO between January 2008 and December 2012. The WHO is coordinating a vaccination campaign to reduce the number of cases of measles. Between seven to ten days after receiving the vaccination for measles the concentration of antibodies in the blood begins to increase. Describe what happens in the body after the injection of a measles vaccine until the concentration of antibodies in the blood begins to increase. Explain why countries that have established vaccination programmes still have cases of measles.
11. Immunity  →  11.2. Antibodies and vaccination
10. Infectious diseases  →  10.1. Infectious diseases
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