No questions found
(a) (i) Show clearly on Fig. 1.1 what you would expect the contents of the test-tube to look like after 10 minutes. You will gain marks for clear labels.
You are required to investigate the effect of the independent variable, pH, on the sedimentation of a yeast cell suspension over a period of 10 minutes.
(ii) State the time intervals you will use and what you will use the graph paper scale to measure.
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[2]
(iii) Use the test-tube labelled T and the other apparatus provided and decide on the volume of Y and the volume of each buffer solution to use.
Describe all the steps you used to work out the volumes.
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State the volume of Y and the volume of each buffer solution to use.
volume of Y .................................................
volume of each buffer solution ..........................
[1]
(iv) Prepare the space below and record your observations.
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[5]
(v) Use your results to state the effect of pH on the yeast suspension.
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(vi) Identify one significant source of error in this experiment.
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(vii) State the degree of uncertainty of using the graph paper scale as a measure.
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(viii) Suggest how you could make this investigation
as accurate as possible,
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as reliable as possible.
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[3]
(b) (i) Plot a graph of the data shown in Table 1.1.
[4]
(b) (ii) State the concentration of calcium chloride required for the yeast to sediment out at 40 minutes.
You may lose marks if you do not show your working or if you do not use appropriate units.
concentration of calcium chloride required ..................................................... mmol
[1]
505
539
583
M1 is a slide of a stained transverse section through a plant organ.
(a) (i) Select a large vascular bundle and draw a large plan diagram of the vascular bundle.
Label the xylem tissue.
(ii) The epidermis has hair-like structures called trichomes.
Make a high-power drawing of one trichome, made up of at least three cells, and one epidermal cell on each side touching the base of the trichome.
Label the trichome.
Fig. 2.1 is a photomicrograph of a stained transverse section of a different plant organ.
(b) (i) Calculate the ratio of the total diameter of the plant organ labelled $Y$ to the diameter of the vascular tissue labelled $X$.
You may lose marks if you do not show your working or if you do not use appropriate units.
(ii) Prepare the space below so that it is suitable for you to describe the observable differences between M1 and Fig. 2.1.
Record your observations in the space you have prepared.
533
574
564
