3. Enzymes
A section of Biology, 9700
Listing 10 of 276 questions
Researchers isolated a sucrase enzyme from the bacterium Bacillus subtilis. They immobilised the enzyme in alginate beads. The researchers investigated the effects of temperature on the activity of the immobilised sucrase compared with the activity of the same enzyme free in solution. The results are shown in . temperature / °C percentage of maximum enzyme activity sucrase free in solution immobilised sucrase key With reference to , compare the effects of temperature on the activity of immobilised sucrase with the activity of sucrase free in solution. The researchers also investigated the effects of pH on the activity of the immobilised sucrase compared with its activity free in solution. The results are shown in . 7.5 8.0 3.0 3.5 4.0 4.5 5.0 pH 5.5 6.0 6.5 7.0 percentage of maximum enzyme activity sucrase free in solution immobilised sucrase key shows that immobilised sucrase remains active over a wider range of pH compared with sucrase free in solution. Suggest reasons for the higher activity of immobilised sucrase over the range of pH between 5.5 and 8.0. State one variable that the researchers should keep constant in both investigations and explain your answer in terms of enzyme action. variable explanation There are many advantages of using immobilised enzymes in industry. Suggest two advantages of using immobilised enzymes in industry other than remaining active over a greater range of pH.
9700_s18_qp_21
THEORY
2018
Paper 2, Variant 1
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The fig tree, Ficus carica, and the papaya tree, Carica papaya, produce a milky-looking fluid known as latex. The latex is released when plant tissue is wounded and it is thought to act as a defence against attack by herbivorous insects or parasitic worms. Latex is a complex mixture of substances and the exact composition of the mixture depends on the plant species. A group of enzymes that hydrolyse proteins, known as cysteine proteases, are commonly found in latex. Ficin, found in F. carica, and papain, found in C. papaya, are both cysteine protease enzymes. These enzymes have been extracted and purified for use commercially. An investigation was carried out to compare the effect of temperature on the activity of ficin and papain. The results are shown in . temperature / °C percentage of maximum activity papain ficin With reference to , describe the differences between the activity of papain compared to the activity of ficin between 20 °C and 80 °C. Ficin and papain have been shown to be effective in the digestion of parasitic nematodes . With reference to , explain which enzyme you would select to use in an oral medication for the treatment of human intestinal parasitic nematodes. One commercial use of the enzyme ficin is the production of Fab fragments (antigen binding regions) of mouse IgG antibodies for use in immunological studies. The process uses immobilised ficin to cleave the antibodies in the hinge region. Suggest one practical advantage of using immobilised ficin for this process, rather than ficin free in solution. Streptococcus pyogenes is a bacterium that can cause a range of diseases in humans. S. pyogenes synthesises streptopain, a cysteine protease that hydrolyses structural proteins in human connective tissue. Streptopain is secreted to the outside of the cell. State the term given to an enzyme that is produced by a cell and is then secreted to the outside, where it has its action. Suggest one example of a structural protein in connective tissue that can be hydrolysed by streptopain.
9700_s18_qp_23
THEORY
2018
Paper 2, Variant 3
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