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0708-AS Biology Revision Top Priority Questions

Chapter 1
1- Fig.1.1 is an electron micrograph of a mesophyll cell from a leaf.



(a) Calculate the magnification of Fig.1.1. Show your working and express your answer to the nearest whole number.
(b) Identify, by using the letters A to D, a part of the cell shown in Fig. 1.1 where the following substances are located.
A chlorophyll
B cellulose
D phospholipid
(c) State three ways in which the structure of a red blood cell differs from the structure of the cell shown in Fig.1.1.


0708-AS Biology Revision Top Priority Questions


2- Fig.1.2 is a diagram of a bacterium.

(a) Name structures Q to S.
(b) State the names of three
…show more content…
Explain how a non-competitive inhibitor acts on an enzyme to prevent it catalysing a reaction. You may use an annotated diagram to illustrate your answer if you wish.

3- A solution of the enzyme amylase was added to a solution of starch and kept at 25°C.
The starch was broken down by hydrolysis.
Explain how you would determine the rate of hydrolysis.

4- A solution of starch was poured into six separate test-tubes, labelled F to K. The test tubes were kept at 35 °C for 5 minutes and then treated as shown in Table 3.3. After a further 30 minutes the contents of the test-tubes were tested for the presence of reducing sugar.
Table 3.3.

Explain the results shown in Table 3.3.

5- Enzymes catalyse reactions in which substrate molecules are converted to products.
(a) There are two main approaches to investigation of the activity of an enzyme. State the two ways in which the activity of an enzyme can be found.

0708-AS Biology Revision Top Priority Questions


Phosphatase enzymes remove phosphate groups from a wide range of organic compounds that contain phosphate. This makes available a supply of phosphate ions within cells. The reaction catalysed by phosphatase enzymes is as follows: phosphatase enzyme
X = an organic compound

X + PO4


The activity of phosphatase was measured at different values of pH by using nine different buffer solutions. The temperature was kept constant at 30 °C. The results