5. Enzymes
A section of Biology, 0610
Listing 10 of 248 questions
Quinoa, Chenopodium quinoa, is a dicotyledonous plant that produces seeds that resemble those of cereals, such as rice. State one feature shown by all dicotyledonous plants. During seed development, amino acids are converted into storage proteins and proteases. Protease molecules become active when the seed absorbs water at the start of germination. shows the formation of a storage protein and a protease in developing quinoa seeds and the action of protease on the storage protein during germination. part of a protease molecule amino acids in seeds protein synthesis in seeds protease breaks down storage protein part of a storage protein molecule supply of amino acids in the germinating seed During seed development in quinoa some genes are ‘switched on’. Define the term gene. Describe the differences in structure between the storage protein and the protease shown in . State the roles of mRNA and ribosomes in protein synthesis. mRNA ribosome Researchers investigated the effect of pH on the activity of the protease in quinoa seeds. The results are shown in . 0.0 2.0 2.5 3.0 4.0 5.0 6.0 7.0 6.5 5.5 4.5 3.5 0.1 0.2 0.3 0.4 0.5 0.6 pH enzyme activity / arbitrary units State two factors other than pH that would affect enzyme activity. Describe the effect of increasing pH on the activity of the protease in quinoa seeds. Explain the activity of protease at pH 4.0 and at pH 7.0.
0610_s17_qp_43
THEORY
2017
Paper 4, Variant 3
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is a diagram of the digestive system. A B C G D E F H J L K Each letter may be used once, more than once or not at all. State the letter of the part shown in : that produces bile that produces gastric juice that produces urea where maltose is digested where trypsin acts. A student investigated the effect of bile on the digestion of fat in milk. They set up three different test-tubes: • test-tube A contained milk and bile • test-tube B contained milk and lipase • test-tube C contained milk, lipase and bile. They used an indicator that is pink in alkaline solutions and colourless in acidic solutions. They added the same volume of indicator to each test-tube. The student observed and recorded the colour of the contents of each test-tube at 0 minutes, 20 minutes and 40 minutes. Table 1.1 shows the results of the investigation. Table 1.1 test-tube indicator colour observed 0 minutes 20 minutes 40 minutes A pink pink pink B pink pink colourless C pink colourless colourless Explain the results for test-tubes B and C in Table 1.1. Explain the purpose of test-tube A in Table 1.1. The action of lipase is affected by temperature. shows the axes for a graph of the effect of temperature on the activity of lipase. Complete the graph by: • drawing a line to show the expected effect of temperature on the activity of lipase • adding a label line and a label to show the point at which all the lipase has been denatured. enzyme activity temperature Explain why lipase cannot be used to catalyse the breakdown of proteins.
0610_s23_qp_41
THEORY
2023
Paper 4, Variant 1
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Questions Discovered
248