2018 Collated Biomolecules & Enzymes STQ QP.pdf

2018 Collated Biomolecules and Enzymes (DNA, Gene Expression) STQ 2018 / H2 / AJC PRELIM / P2 Q21Fig. 1.1 shows the effect of pH on the activity of a protease enzyme at the optimal temperature of 37oC. Fig. 1.1(a)Draw, on Fig. 1.1, the approximate shape of the curve if the same experiment is conducted at 25oC.[1](b)Explain with reasons the shape of the curve you have drawn.……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….[2]

(c)Using information from the graph, explain why proteases stored in vesicles with pH 7.2 cannot break down vesicular membrane proteins and suggest how these proteases can be activated through increase in pH.……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….……………………………………………………………………………………………….[6][Total: 9]

2018 / H2 / EJC PRELIM / P2 Q1 ( Cancer Eukaryotic Cell Structure)2The synthesis of collagen is shown in Fig. 1.1. CProcess B(tropocoFig. 1.1(a)(i)Describe two important functions of structure A in the synthesis of collagen. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… …………………………………………………………………………………………………...[2](ii)Tropocollagen leaves the cell to be assembled to form collagen fibrils via Process B. Outline Process B.

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………[3](b)Suggest how chemical modification such as hydroxylation in organelle C results in collagen having a high tensile strength. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………[2]Fig. 1.2 shows two electron micrographs. One of the electron micrograph shows part of a normal cell while the other electron micrograph shows part of a cancer cell. The white arrows point to an organelle within the cell. The appearance of this organelle in both cell types were visibly different. The cancer cell had a higher activity than the normal cell. Organelle (indicated by white arrows) in a normal cellOrganellarrows) iFig. 1.2(c)(i)Describe the visible difference between the organelle indicated by the white arrows in Fig. 1.2, between the cancer cell and the normal cell. ………………………………………………………………………………………………………………………………………………………………………………………………………[1](ii)Account for the higher activity of the cancer cell.

……………………………………………………………………………………………………