1. The antibiotic ampicillin is an inhibitor of the enzyme transpeptidase. The growth in the number of cells of the eukaryotic green alga Closterium was monitored under a microscope every day after ampicillin treatment. Each Closterium cell contains two chloroplasts. The graph shows the growth curve of cells grown without and with ampicillin.
(a) Calculate the difference in the number of cells after five days of treatment without ampicillin and with ampicillin.
(b) Outline the effect of 100 μmol dm–3 ampicillin on the growth of cells.
The effect of ampicillin on chloroplast division was studied in Closterium. When Closterium cells enter the cell division process, chloroplasts start to divide, forming two new cells with two chloroplasts each. In the medium with 100 μmol dm–3 ampicillin, various types of cells can be observed. The bar chart shows the frequency of different cells produced without and with ampicillin.
(c) State the frequency of cells grown with ampicillin on day 3 that contain one chloroplast.
(d) Compare the frequency of different types of cells grown without and with ampicillin on day 5.
(e) Analyse the effect of ampicillin on Closterium cells.
2. The diagram shows a section through the surface of an animal cell.
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(a) On the diagram label the membrane components I and II.
(b) (i) On the diagram label III.
(ii) State one function of III.