2 marksMolecules may move by the process of diffusion.
Define the term 'diffusion'.
2 marksGive two reasons why diffusion is important to living organisms.
3 marks
Fig. 1
Identify substances A, B and C.
2 marksDescribe the movement of substance A in Fig. 1.
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1 markFig. 1 shows particles of two gases.
Fig. 1
Sketch the arrangement of the gas particles after 1 hour.
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2 marksWater is important for living organisms as many substances are able to dissolve in it.
Give two examples of the importance of water as a solvent in living organisms.
1 markFig. 1 shows water and a sugar solution separated by a partially permeable membrane.
Fig. 1
State the overall direction in which water molecules will move.
2 marksOsmosis occurred in Fig. 1.
Define the term 'osmosis'.
2 marksA second beaker, similar to the one from Fig. 1, was set up and placed in a water bath that was 10°C lower than the beaker from Fig. 1.
Explain how the movement of the water molecules would be affected by this decrease in temperature.
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2 marks
Fig. 1
Identify the correct description for each cell by drawing a line between the cell and the box that contains the most accurate description.
2 marks
Fig. 2
Each beaker contained potato discs in a solution of sugar or distilled water. The student found that the potato discs in Beaker 5 decreased in mass.
Explain the reason for this.
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3 marksFig. 1 shows the structure of an alveolus with a capillary running next to it.
Fig. 1
If concentrations of PM are high, the epithelium cells of the alveoli may be killed and replaced with unspecialised cells resulting in:
Explain how particulate matter would affect the process of gas exchange in human lungs.
3 marks
Fig. 2
Scientists studied 31 080 alveolar epithelium cells in this study.
Calculate how many more cells died after 48 hours of exposure to 1 000 µg cm-3 of particulate matter than after 48 hours of exposure to 50 µg cm-3 of particulate matter.
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5 marksThey cut a potato into cubes and recorded the change in mass over a 30 minute period.
Fig. 1 shows the results the student obtained from one cube of potato.
Describe and explain the trend shown on the graph.
2 marksThe potato cube from Fig. 1 had an initial mass of 2.5 g.
Calculate the percentage increase that the potato cube had shown after 15 minutes.
2 marksThe student repeated the investigation but with the beaker placed in a water bath at 30°C.
Draw a second line on the graph to show the trend expected from these results.
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3 marksDiabetes insipidus is a disease that results in a large amount of dilute urine being excreted by the kidneys. This leads to blood which is more concentrated than normal.
Explain the effect that diabetes insipidus may have on red blood cells.
2 marksOne of the symptoms of diabetes insipidus is blue fingernails, which indicates a lack of oxygen.
Suggest an explanation for this.
3 marksCentral diabetes insipidus is a form of the disease that is believed to have a negative effect on the bone density of a sufferer which may leave them with an increased risk of sustaining fractures.
A study was conducted on the effect of central diabetes insipidus on the risk of sustaining fractures.
Fig. 1 shows the results of this study.
Fig. 1
Calculate the difference in the number of men suffering from fractures between those with diabetes insipidus and those without. Show your calculations.
[3]
4 marksThe scientists concluded that diabetes insipidus does increase the risk of sustaining fractures.
Evaluate this conclusion.
[4]
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2 marksSome people suffer from coeliac disease that affects the lining of their small intestine.
Fig. 1 compares the lining of the small intestine of a healthy person and a person suffering from coeliac disease.
Fig. 1
Based on the information provided, explain the effect that coeliac disease would have on the absorption of monoglycerides.
3 marks
Fig. 2
Describe and explain what the graph shows.
3 marksHuman body temperature is approximately 37 °C, which provides the optimum temperature for activity of protein molecules such as enzymes.
Suggest why a temperature of 37 °C helps to maximise the rate of transport of substances across the cell membrane.
3 marks
Fig. 3
Describe and explain the movement of water between the cells in Fig. 3.
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3 marksThey used the following method:
Fig. 1 represents the graph that was drawn of the percentage change in mass.
Fig. 1
Use the information in Fig. 1 to describe the results obtained in each beaker.
3 marksUse the graph in Fig. 1 to identify the concentration of the sugar solution where the mass of the egg would not change.
[1]
Explain why the mass of the egg would not change at the concentration identified at part (i).
[2]
3 marks4 marksDiffusion and osmosis are two ways in which molecules can move.
Compare diffusion and osmosis with each other.
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1 mark
Fig. 1
Which of the plant cells above (A or B) was placed in a solution that was more dilute than the cell contents?
4 marks4 marksFig. 2 below shows a red blood cell.
Fig. 2
Describe what would happen if a red blood cell was placed in a solution that was more dilute than the cell contents.
[2]
Explain why the description at part (i) would be different from what would happen to a plant cell.
[2]
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