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1. The diagram shows two cells, a bacterial cell and a plant cell.

a)Both the bacterial cell and the plant cell contain ribosomes.What is the function of a ribosome?

b)The plant cell contains mitochondria but the bacterial cell does not contain mitochondria.

i)Give one other way in which the plant cell is different from the bacterial cell.

ii)Most mitochondria are about 3 micrometres in length. Use the information in the diagram to suggest why the bacteria do not contain mitochondria.

c)Which part of a plant cell contains chlorophyll?

d)Both cells are drawn the same length, but the magnification of each cell is different.

The real length of the bacterial cell is 2 micrometres.
Calculate the real length, X, of the plant cell. Give your answer in micrometres.
In your jotter, show clearly how you worked out your answer.

2. Euglena is a free moving freshwater unicellular organism that lives freshwater ponds. In its natural habitat, Euglena gains water by osmosis. Unwanted water is removed by the contractile vacuoles. Each filling and emptying of a contractile vacuole is called a pulsation.

In an experiment, specimens of Euglena were placed in solutions of different concentrations of salt and viewed under the microscope. The table gives the results from the observations of 7 animals.

a) Plot the data on a line graph in your jotter.

b) What is the relationship between the salt concentration of the solution and their water concentration?

c) Describe the relationship between the water concentration of the salt solution and the time taken for one pulsation? Explain why this relationship would exist.

d) Name the process that the contractile vacuoles are carrying out.

e) The experiment was repeated using solutions of pure water and 1% salt solutions. In one of these solutions the contractile vacuoles stopped working.

 i. Which liquid would the contractile vacuole stop working? Explain your choice.

ii. Suggest how the contractile vacuole would respond to the other solution.

iii. What effect would this second solution have on human cheek epithelium cells?

f) Identify the variable factor in this experiment involving Euglena.

g) Name two other factors that must be kept constant in order to make the procedure valid.

h) In the experiment, why was the average value calculated for each salt concentration?

3. The diagram below illustrates one of the stages of protein synthesis.

a) Name bases 10, 11 and 12.

b) Where in the cytoplasm does the mRNA move to next?

c) Describe the part played by an mRNA molecule in the manufacture of a cell protein.

d) Apart from mRNA, what other molecule will be needed for the synthesis of proteins?

4. The experiment shown below was set up to demonstrate aerobic respiration in peas that are germinating (starting to grow).

After two days, the level of liquid had risen in tube Y but had not risen in tube X.

After two days, the level of liquid had risen in tube Y but had not risen in tube X.

a) Explain the purpose of A as a control in this experiment.
b) Predict the effect on the level of the liquid in tube Y if a greater mass of peas is used.
c) What happens to the volume of gas in test tube B?Explain why this change occurs.
d) Explain why the liquid in tube Y rises in this experiment.
e) The following list contains some features of aerobic and anaerobic respiration in germinating peas.
List

W Does not use oxygen
X Produces carbon dioxide
Y Yields 38 molecules of ATP per glucose molecule
Z Produces ethanol

Copy and complete the table below by writing the letters from the list in the correct columns.

Each letter may be used once or more than once.

 

5.The diagram shows an industrial fermenter. It is fitted with a number of taps which allow substances to be added or removed.

Barley malt extract, water and yeast were placed in the fermenter and left for several days.

The rate of fermentation was measured and the results are shown in the graph below.

a) Describe the changes in the rate of fermentation over the ten days.
b) Suggest a reason for the change in the rate of fermentation between points A and B.
c) A temperature probe in the fermenter malfunctioned and the temperature exceeded 70°C.The yeast died and fermentation stopped.Explain why fermentation stopped.

d) Which of the taps, A, B, C, D or E, would open to
i) add nutrients to the mixture?
ii) remove waste gases?
iii) drain off the products?
e) The fermenter should be kept at 35 °C. Explain why the water jacket around the fermenter needs to be cold.

b) Describe the changes in the rate of fermentation over the ten days.
c) Suggest a reason for the change in the rate of fermentation between points A and B.
d) A temperature probe in the fermenter malfunctioned and the temperature exceeded 70°C.The yeast died and fermentation stopped.Explain why fermentation stopped.
 6. A gardener grew a crop of peas in a polythene tunnel.

 

a) State two conditions that could limit the rate of photosynthesis in the pea plants.

b) The graph below shows the mass of sugar in the leaves and the concentration of carbon dioxide just above the pea plants at different times of the day.

(i) For how many hours did the carbon dioxide concentration decrease?

(ii) Explain this decrease in carbon dioxide concentration.

(iii) Explain why the mass of sugar in the leaves is as its maximum at 1600.

(iv) Calculate the percentage increase in sugar in the leaves between 0400 and 1600.

(v) Explain why the mass of sugar decreases between 2000 and 0000.

7. In the boxes below, describe each of the steps carried out to transfer successfully a human gene into a bacterial cell