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1 There are goblet cells in many parts of the alimentary canal.
State the substance that goblet cells secrete.
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[Total: 1]
2 Cartilage is another tissue found in the gas exchange system.
State the functions of cartilage in the gas exchange system.
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3 The diagram shows part of the gas exchange surface of a human.
State two features of the gas exchange surface that are visible in the diagram.
1 ...............................................................................................................................................
2 ............................................................................................................................................... [2]
[Total: 2]
3
4 The gas exchange system is one of the organ systems of the human body.
The diagram shows parts of the gas exchange system during breathing in and breathing out.
Complete the table to show:
• the functions of the diaphragm and the intercostal muscles during breathing in and
breathing out
• the pressure changes in the thorax.
Use these words:
contract
relax
increases
decreases.
intercostal muscles pressure change in
diaphragm
internal external the thorax
breathing in
breathing out
[4]
[Total: 4]
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5 Explain how the human gas exchange system is protected against pathogens.
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6 Scientists grew Soybean plants, Glycine max, in two separate plots.
Each plot used a carbon dioxide enrichment system to control the atmospheric carbon dioxide
concentration.
The atmospheric carbon dioxide concentrations in the two plots were kept at:
• 370 ppm, which is similar to the current atmospheric carbon dioxide concentration
• 550 ppm, which is a possible future atmospheric carbon dioxide concentration.
When the scientists were working in the plot with a carbon dioxide concentration of 550 ppm, their
breathing rates were higher than when they worked in the other plot.
Suggest why their breathing rates were higher.
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[Total: 2]
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7 During inspiration the pressure and volume in the thorax changes.
State these changes.
pressure ...................................................................................................................................
volume ..................................................................................................................................... [1]
[Total: 1]
8 Alveoli are well-ventilated to provide efficient gas exchange.
State the name of the muscles that cause the ribs to move during ventilation.
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[Total: 1]
9 State two ways in which the composition of inspired air differs from the composition of expired air.
1 ...............................................................................................................................................
2 ............................................................................................................................................... [2]
[Total: 2]
3
10 (a) A small sample of yeast cells and 19 g per dm of sugar were added to a fermenter. The
population size of live yeast cells and the concentration of the sugar in the fermenter were
calculated every day for 10 days.
The results are shown in graph 1 and graph 2.
graph 1
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graph 2
(i) Complete the line on graph2 to show the expected change in the population size of
live yeast cells from day 3 to day 10. [2]
7
(ii) Describe and explain the changes in the concentration of sugar in the fermenter over
the 10-day period.
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[Total: 7]
11 If exercise is very intense an oxygen debt is formed.
Outline how the body removes an oxygen debt.
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12 Yeast is an example of a single-celled fungus.
The population of yeast can be estimated by using a light microscope to view a small sample of
yeast cells in a modified microscope slide.
There is a square chamber, with a specific volume, cut into the microscope slide and a grid to make
it easier to count the number of cells.
The diagram shows a modified microscope slide. It also shows part of a light microscope with the
modified microscope slide filled to the top with a sample of yeast cells.
The length of the sides of each small square in the grid in the modified microscope slide is 200 µm.
The depth of the chamber is 100 µm. There is a total of 25 small squares in the grid.
Each small square in the grid has an average of 52 yeast cells.
3
Calculate the concentration of yeast cells per mm .
Space for working.
3
.............................................. cells per mm [3]
[Total: 3]
9
13 Yeast is used in the production of ethanol to manufacture a type of biofuel.
The diagram is a flow chart of the process.
Yeast is used in process U. Complete the balanced chemical equation for anaerobic respiration in
yeast.
................................. → ...........C2H5OH + .................. [2]
[Total: 2]
14 Describe the role of the liver in the recovery from oxygen debt after strenuous exercise.
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[Total: 2]
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15 Complete the sentences about aerobic and anaerobic respiration.
Use words or phrases from the list.
Each word or phrase may be used once, more than once, or not at all.
carbon dioxide carbon monoxide energy
fatty acids glycerol guard lactic acid
mesophyll muscle nitrogen oxygen
Anaerobic respiration is different to aerobic respiration because ...........................................
is not needed to break down glucose molecules.
The amount of ........................................ released from each glucose molecule is much
smaller in anaerobic respiration.
Anaerobic respiration in humans takes place in ................................. cells during vigorous
exercise. It produces ..................................... from glucose.
A different form of anaerobic respiration takes place in yeast cells. Here the glucose is
broken down into alcohol and ................................... .
[5]
[Total: 5]
16 The liver is involved in the processing of toxins.
Lactic acid is an example of a toxin that is produced during vigorous exercise and processed in the
liver.
Describe how lactic acid is processed.
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[Total: 2]
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17 Describe how horses recover from an oxygen debt when they stop exercising.
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[Total: 4]
18 State the balanced chemical equation for aerobic respiration.
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[Total: 2]
12
19 Researchers in Chile investigated the rate of respiration in crickets.
They investigated the effect of temperature and body mass on the rate of respiration. They measured
the rate of oxygen consumption in crickets with different body masses, at different temperatures.
The researchers’ results are shown in the graph below.
State two conclusions that can be made from the data in the graph and support each conclusion
with evidence from the graph.
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20 Researchers in the Czech Republic investigated oxygen consumption in horses. They measured
the oxygen consumption of the horses while they were exercising at four different paces: walking,
trotting, cantering and galloping.
The results are shown in the graph below.
The researchers also calculated the oxygen debt for each type of exercise.
They found that the horses developed a larger oxygen debt when they exercised by galloping and
cantering rather than when they walked.
Explain why the horses developed an oxygen debt when they exercised.
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21 A respirometer is shown in the diagram below. It can be used to estimate an organism’s rate of
respiration.
A student used a respirometer to investigate the effect of temperature on the rate of respiration of
germinating seeds.
Predict the results of this investigation and explain your prediction.
prediction .................................................................................................................................
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explanation ...............................................................................................................................
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[Total: 4]
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22 If exercise is very intense an oxygen debt is formed.
Complete the sentence.
An oxygen debt results in a build-up of ................................................ in the
................................................ during vigorous exercise. [2]
[Total: 2]
23 Some countries have invested in biofuels such as ethanol, biomass and biodiesel.
Describe how ethanol can be made by microorganisms.
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[Total: 2]
24 State three uses of energy in the human body.
1 ...............................................................................................................................................
2 ...............................................................................................................................................
3 ............................................................................................................................................... [3]
[Total: 3]
16
25 The bacterium Bacillus megaterium was grown in the laboratory fermenter shown in the diagram.
Explain why a source of nitrogen and glucose were added to the fermenter.
nitrogen ....................................................................................................................................
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glucose......................................................................................................................................
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[Total: 2]
17
26 Students investigated the rate of respiration of crickets (a type of insect) using a carbon dioxide
sensor and laptop as shown in the photograph below. The sensor was fitted inside an airtight glass
jar. The apparatus was set up in a room with a constant temperature of 17 °C.
The students found that the concentration of carbon dioxide inside the jar increased by 50 ppm in
120 seconds.
During the investigation the temperature inside the jar increased. The temperature outside the jar
remained constant.
Explain why the temperature inside the jar increased.
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[Total: 2]
18
27 Researchers in the Czech Republic investigated oxygen consumption in horses. They measured
the oxygen consumption of the horses while they were exercising at four different paces: walking,
trotting, cantering and galloping.
The results are shown in the graph below.
Calculate the percentage increase in the average rate of oxygen consumption as the horses change
from walking to trotting.
Show your working.
........................... % [2]
[Total: 2]
19
28 A respirometer is shown in the diagram below. It can be used to estimate an organism’s rate of
respiration.
Complete the sentences:
A respirometer can be used to calculate the ............................. of oxygen used by the fly larvae by
measuring the ............................. the droplet of oil moves in one minute. A water-bath is used to
............................. the temperature of the apparatus. [3]
[Total: 3]
29 State the balanced chemical equation for aerobic respiration.
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[Total: 2]
20
30 Students investigated the rate of respiration of crickets (a type of insect) using a carbon dioxide
sensor and laptop as shown in the photograph below. The sensor was fitted inside an airtight glass
jar. The apparatus was set up in a room with a constant temperature of 17 °C.
The students found that the concentration of carbon dioxide inside the jar increased by 50 ppm in
120 seconds.
After 10 minutes, the students opened the jar by removing the sensor. They left the jar open for 5
minutes but made sure that the crickets remained in the jar. They then replaced the sensor and
took more readings for another 10 minutes.
State and explain one reason for opening the jar after 10 minutes.
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[Total: 2]
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31 A respirometer is shown in the diagram below. It can be used to estimate an organism’s rate of
respiration.
The soda lime in the respirometer absorbs carbon dioxide.
Explain why this is important in this investigation.
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[Total: 1]
