6. Identify the most accurate description of the membrane structure from the given responses:
Jason : The walls of the membrane are pretty solid. Not many substances can pass through the walls as only certain molecules are required. There are proteins which can accept some specific ions or molecules and the cell membrane has channels.
Henry: The phospholipid bilayer follows the fluid-mosaic model and protein pumps energise the molecules from the inner membranes in active transport from higher to lower concentration. The membrane will have pores which allow diffusion of products.
Amy : The membrane will contain ion channels which will allow the diffusion of ions and the entire membrane is selectively permeable with a double layer of phospholipid and pumps penetrating through the bilayer enabling active transport.
Hanna : Well the membrane consists of phospholipid, protein and enzyme molecules and the protein pores generate an electrical gradient enabling the transport of certain molecules. The whole membrane is characterised by its fluidity and permeability.
7. Assume a graph with the relative rate of reaction plotted on the Y axis and the increasing substrate concentration on the X axis. A line is plotted showing the relationship without the inhibitor. What is the limiting factor of the reaction rate?
The total number of enzymes present in the reaction.
The total number of inhibitors present in the reaction.
The concentration of the end product.
The size of the multi-enzyme complex.
8. An enzyme A has a specific affinity to substrate of type B. However the biological catalyst has no effect on the substrate of type B due to the presence of a competitive inhibitor. What can increase the likelihood of the substrate of type B binding?
By increasing the velocity of the substrate relative to the velocity of the inhibitor molecules.
Increase in the concentration of the substrate of type B which will diminish the probability of a competitive inhibitor binding.
Introduction of non-competitive inhibitors which will counteract the competitive inhibitors.
Lowering the temperature of the reaction in order to deactivate the competitive inhibitors.
9. Select the correct words for completion of the following : Enzymes are (A) catalysts responsible for (B) and thus enabling the (C) to be lowered. A metabolic (D) can occur due to a (E) which can result in a depletion or accumulation of metabolites.
A: Natural B: increasing the rate of chemical reactions C:reaction energy D:discontinuation E:genetic mutation
