Hint: Q 51 to 56 deal directly with dilution factors. You should have no problems with these six questions. If you do, it is worth your while sorting them out before you attempt the rest of the questions in the section.
51. To
make
a solution of 1 mM of NaOH, you could mix:
20
mM NaOH water
1.
1 ml
19 ml
2.
1
ml
20 ml
3.
0.5
ml
9.5 ml
4.
10 ml
990 ml
5.
10 ml
0.9 ml
52. To make a solution containing 5 mM glucose you could mix:
20 mM glucose water
1.
12.5
ml
27.5 ml
2.
12.5
ml
37.5 ml
3.
10.0
ml
27.5 ml
4.
10.0
ml
37.5 ml
5.
5.0
ml
5.0 ml
53. To dilute a solution of tissue homogenate to one-tenth of its original concentration, take 1 ml of the solution and mix it with the following volume of buffer (in ml):
1.
0.1
2.
1.0
3.
1.1
4.
9
5.
10
54. To dilute a solution of tissue homogenate to one-twentieth of its original concentration, take 1 ml of the solution and mix it with the following volume of buffer (in ml):
1.
0.05
2.
1.05
3.
19
4.
20
5.
21
55. To dilute an aqueous solution of glucose to 40% of its original concentration, take 100 ml of the solution and mix it with the following volume of water (in ml):
1.
40
2.
150
3.
200
4.
250
5.
400
56. To dilute an aqueous solution of ethanol to 20% of its original concentration, take 10 ml of the solution and mix it with the following volume of water (in ml):
1.
25
2.
30
3.
40
4.
50
5.
90
57. If 50 ml of a 10 molar solution of NaOH is diluted with water to a total volume of 1 ml, the final concentration of NaOH is:
1.
1 M
2.
500 mM
3.
100 mM
4.
50 mM
5.
5 M
58. You add 100 ml of enzyme to 1.1 ml buffer and 300 ml 5 mM substrate. The final concentration of the substrate is:
1.
0.33 mM
2.
1 mM
3.
1.1 mM
4.
5 mM
5.
none of the above
59. If you put 0.5 ml of 3 mmol.litre-1 4-nitrophenol phosphate and 0.4 ml of buffer in a test tube and start the reaction by adding 100 ml of a 1 mg.ml-1 protein solution containing alkaline phosphatase, what is the final concentration of protein in your tube?
1.
0.1 mg.ml-1
2.
0.1 mg
3.
1 mg.ml-1
4.
0.5 mg.ml-1
5.
0.1 mg.ml-1
60. The activity of a preparation of alcohol dehydrogenase is determined in a spectrophotometer. The cuvette contains 2.0 ml of buffer, 0.5 ml of NADH and 0.5 ml of ethanol. The reaction is started by adding 0.5 ml of the preparation of alcohol dehydrogenase, which contains 0.84 mg of protein per ml. The concentration of protein in the reaction mixture in the cuvette is:
1.
0.12 mg.ml-1
2.
0.14 mg.ml-1
3.
0.84 mg.ml-1
4.
0.42 mg
5.
2.52 mg
61. The activity of a preparation of lactate dehydrogenase is determined spectrophotometrically. The cuvette contains 2.5 ml of buffer, 0.1 ml of NADH and 0.4 ml of pyruvate. The reaction is started by adding 0.1 ml of the preparation of lactate dehydrogenase, which contains 0.93 mg of protein per ml. The concentration of protein in the reaction mixture in the cuvette is:
1.
0.093 mg
2.
0.030 mg.ml-1
3.
0.031 mg.ml-1
4.
0.930 mg
5.
2.79 mg.ml-1
62. The activity of a preparation of aspartate aminotransferase is determined spectrophotometrically. The cuvette contains 2.8 ml of buffered reaction mixture and 0.1 ml of the enzyme preparation, which contains 2.5 mg of protein per ml. The reaction is started by adding 0.1 ml of a-oxoglutarate. The concentration of protein in the cuvette is then (to 2 significant figures):
1.
0.083 mg.ml-1
2.
0.086 mg.ml-1
3.
0.25 mg.ml-1
4.
0.025 mg
5.
0.75 mg
63. The activity of a preparation of alcohol dehydrogenase is determined spectrophotometrically. The cuvette contains 2.0 ml of buffer, 0.5 ml of NADH and 0.5 ml of ethanol. The reaction is started by adding 0.5 ml of the preparation of alcohol dehydrogenase, which contains 0.42 mg of protein per ml. The concentration of protein in the reaction mixture in the cuvette is:
1.
0.06 mg.ml-1
2.
0.07 mg.ml-1
3.
0.42 mg.ml-1
4.
0.21 mg
5.
1.26 mg
64. The absorbance of a 10-5 mol.l-1 solution of NADH, measured at 340 nm, is 0.062. The absorbance of a 1 mol.l-1 solution of NADH solution at 340 nm is therefore:
1.
0.062 x 10-5
2.
2.48
3.
6.2
4.
340
5.
6200
65. The absorbance of 3 ml of a 10-5 mol.l-1 solution of 4-nitrophenol, measured at 400 nm, is 0.18. The absorbance at 400 nm of a 1 mol.l-1 solution of 4-nitrophenol is therefore:
1.
54000
2.
18000
3.
400
4.
1.8
5.
0.18 x 10-5
66. The absorbance of 3 ml of a 10-4 mol.l-1 solution of NADH, measured at 340 nm, is 0.62. The absorbance at 340 nm of a 1 mol.l-1 solution of NADH is therefore:
1.
6200
2.
340
3.
6.2
4.
1.86
5.
0.62 x 10-4
67. The absorbance of a 10-5 mol.l-1 solution of 4-nitrophenol, measured at 400 nm, is 0.18. The absorbance of a 1 mol.l-1 solution of 4-nitrophenol solution at 400 nm is therefore:
1.
18000
2.
400
3.
18
4.
2.48
5.
0.18 x 10-5
68. The absorbance of 1.2 ml of a 10-5 mol.l-1 solution of the protein haemoglobin, measured at 540 nm in a cuvette with a 1 cm light path, is 0.24. The molar absorption coefficient of haemoglobin (defined as the absorption of a 1 mol.l-1 solution in a 1 cm cuvette) is:
1.
0.24 x 105
2.
0.20 x 105
3.
540
4.
0.24 x 10-5
5.
0.20 x 10-5
69. The absorbance of 3 ml of a 10-5 mol/l solution of the dye DCPIP, measured at 578 nm in a cuvette with a 1 cm light path, is 0.15. The molar absorption coefficient of DCPIP (defined as the absorption of a 1 mol.l-1 solution in a 1 cm cuvette) is:
1.
0.05 x 10-5
2.
0.15 x 10-5
3.
578
4.
0.05 x 105
5.
0.15 x 105
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