No questions found
Fig. 1.1 shows apparatus that can be used to measure the loss of water vapour from leaves.
The water vapour given out by the area of leaf under the cup increases the pressure inside the tubing, causing the water level in the graduated tube to go down.
Some students used the apparatus in Fig. 1.1 to test the hypothesis:
The loss of water vapour from the lower surface of the leaves of a plant is greater per unit time than the loss of water vapour from the upper surface of the leaves of the same plant.
(a) (i) State the independent variable and the dependent variable in this investigation.
independent variable .........................................................................................................................
....................................................................................................................................................
dependent variable ..........................................................................................................................
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(ii) Describe a method by which the students could use the apparatus shown in Fig. 1.1 to measure loss of water vapour in order to test the hypothesis.
Your method should be set out in a logical order and be detailed enough to let another person follow it.
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(b) The hypothesis that the students tested was:
The loss of water vapour from the lower surface of the leaves of a plant is greater per unit time than the loss of water vapour from the upper surface of the leaves of the same plant.
The students decided that, to make a valid comparison, they needed to work out the water loss per unit time per unit area of leaf.
(i) Describe how the students obtained the measurement needed to work out the results as per unit area of leaf.
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....................................................................................................... [2]
(ii) Describe how the students could use this measurement and their results for the loss of water vapour to find out if their results support the hypothesis.
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(iii) Sketch a bar chart on Fig. 1.2 to show the results if the hypothesis was supported. You should include the axis labels and the units.
[3]
(c) The apparatus shown in Fig. 1.1 was used in another series of experiments to measure water vapour loss from the same leaf in different experimental conditions for the same period of time.
Table 1.1 shows the results.
[Table_1]
(i) On Table 1.1, draw circles around two of the values that may be anomalous. [2]
(ii) The aperture of stomata affects the loss of water vapour.
State one conclusion that can be made about the effect of experimental conditions on the aperture of stomata in this plant.
..................................................................................................................................... [1]
518
566
538
Fig. 1.1 shows apparatus that can be used to measure the loss of water vapour from leaves.
The water vapour given out by the area of leaf under the cup increases the pressure inside the tubing, causing the water level in the graduated tube to go down.
Some students used the apparatus in Fig. 1.1 to test the hypothesis:
The loss of water vapour from the lower surface of the leaves of a plant is greater per unit time than the loss of water vapour from the upper surface of the leaves of the same plant.
(a) (i) State the independent variable and the dependent variable in this investigation.
independent variable .........................................................................................................................
....................................................................................................................................................
dependent variable ..........................................................................................................................
.................................................................................................................................................... [2]
(ii) Describe a method by which the students could use the apparatus shown in Fig. 1.1 to measure loss of water vapour in order to test the hypothesis.
Your method should be set out in a logical order and be detailed enough to let another person follow it.
.....................................................................................................................
.....................................................................................................................
.....................................................................................................................
.....................................................................................................................
.....................................................................................................................
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..................................................................................................................... [6]
(b) The hypothesis that the students tested was:
The loss of water vapour from the lower surface of the leaves of a plant is greater per unit time than the loss of water vapour from the upper surface of the leaves of the same plant.
The students decided that, to make a valid comparison, they needed to work out the water loss per unit time per unit area of leaf.
(i) Describe how the students obtained the measurement needed to work out the results as per unit area of leaf.
.......................................................................................................
.......................................................................................................
.......................................................................................................
....................................................................................................... [2]
(ii) Describe how the students could use this measurement and their results for the loss of water vapour to find out if their results support the hypothesis.
.......................................................................................................
.......................................................................................................
.......................................................................................................
.......................................................................................................
.......................................................................................................
.......................................................................................................
....................................................................................................... [3]
(iii) Sketch a bar chart on Fig. 1.2 to show the results if the hypothesis was supported. You should include the axis labels and the units.
[3]
(c) The apparatus shown in Fig. 1.1 was used in another series of experiments to measure water vapour loss from the same leaf in different experimental conditions for the same period of time.
Table 1.1 shows the results.
[Table_1]
(i) On Table 1.1, draw circles around two of the values that may be anomalous. [2]
(ii) The aperture of stomata affects the loss of water vapour.
State one conclusion that can be made about the effect of experimental conditions on the aperture of stomata in this plant.
..................................................................................................................................... [1]
551
559
546
Antibiotic resistance of pathogenic bacteria is a worldwide cause for concern. Investigations into the use of antibiotics and their effects use an international unit of measurement, called the defined daily dose (DDD).
The DDD represents the assumed average dose for a drug per day being used to treat a specific disease in adults.
A study investigated the antibiotic resistance of _Streptococcus pneumoniae_. The study was carried out in some European countries and the percentage of _S. pneumoniae_ resistant to the antibiotics penicillin and macrolide was determined.
The results are shown in Table 2.1.
[Table_1]
(a) (i) State _two_ conclusions that can be made about the quantity of these antibiotics used and the percentage of _S. pneumoniae_ resistant to these two types of antibiotic.
1 ...............................................................
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2 ...............................................................
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[2]
(ii) Calculate the ratio of penicillin use between Spain and the Netherlands.
ratio ...............................................................[1]
(b) To find the strength of the relationship between antibiotic use and the percentage resistance in _S. pneumoniae_, a linear correlation test was used. The probability for each value was found using the critical values from a probability table.
(i) State _two_ reasons why this statistical test is suitable for these data.
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[2]
(ii) The results of the test are shown in Table 2.2.
[Table_2]
State what the values in Table 2.2 indicate about the relationship between antibiotic use and antibiotic resistance in _S. pneumoniae_.
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[2]
(c) The disc diffusion method is used to test the effectiveness of different concentrations of antibiotics. Fig. 2.1 shows the results of a disc diffusion test.
Starting with a stock solution of an antibiotic, outline how you would make a serial dilution to produce a range of concentrations of the antibiotic.
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[2]
(d) The disc diffusion test is also used to test for antibiotic resistance. The test may take about five days to complete.
Escherichia coli is a common bacterium in the human intestines that can develop antibiotic resistance and transmit it to other bacteria. It is present in faeces and can also be present in waste water that is discharged into rivers.
Environmental agencies test samples of waste water for antibiotic resistant bacteria. This can be done with the disc diffusion method. A new test was developed to allow estimates of antibiotic-resistant E. coli to be obtained within 24 hours.
Suggest _two_ criteria that environmental agencies could apply when assessing the new test to see whether it is suitable.
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[2]
583
534
600
Antibiotic resistance of pathogenic bacteria is a worldwide cause for concern. Investigations into the use of antibiotics and their effects use an international unit of measurement, called the defined daily dose (DDD).
The DDD represents the assumed average dose for a drug per day being used to treat a specific disease in adults.
A study investigated the antibiotic resistance of _Streptococcus pneumoniae_. The study was carried out in some European countries and the percentage of _S. pneumoniae_ resistant to the antibiotics penicillin and macrolide was determined.
The results are shown in Table 2.1.
[Table_1]
(a) (i) State _two_ conclusions that can be made about the quantity of these antibiotics used and the percentage of _S. pneumoniae_ resistant to these two types of antibiotic.
1 ...............................................................
...............................................................
2 ...............................................................
...............................................................
[2]
(ii) Calculate the ratio of penicillin use between Spain and the Netherlands.
ratio ...............................................................[1]
(b) To find the strength of the relationship between antibiotic use and the percentage resistance in _S. pneumoniae_, a linear correlation test was used. The probability for each value was found using the critical values from a probability table.
(i) State _two_ reasons why this statistical test is suitable for these data.
.................................................................
.................................................................
[2]
(ii) The results of the test are shown in Table 2.2.
[Table_2]
State what the values in Table 2.2 indicate about the relationship between antibiotic use and antibiotic resistance in _S. pneumoniae_.
.................................................................
.................................................................
.................................................................
.................................................................
[2]
(c) The disc diffusion method is used to test the effectiveness of different concentrations of antibiotics. Fig. 2.1 shows the results of a disc diffusion test.
Starting with a stock solution of an antibiotic, outline how you would make a serial dilution to produce a range of concentrations of the antibiotic.
.................................................................
.................................................................
.................................................................
.................................................................
[2]
(d) The disc diffusion test is also used to test for antibiotic resistance. The test may take about five days to complete.
Escherichia coli is a common bacterium in the human intestines that can develop antibiotic resistance and transmit it to other bacteria. It is present in faeces and can also be present in waste water that is discharged into rivers.
Environmental agencies test samples of waste water for antibiotic resistant bacteria. This can be done with the disc diffusion method. A new test was developed to allow estimates of antibiotic-resistant E. coli to be obtained within 24 hours.
Suggest _two_ criteria that environmental agencies could apply when assessing the new test to see whether it is suitable.
.................................................................
.................................................................
.................................................................
[2]
543
522
534
