2019年11月IB生物SL真题下载-Paper3
1. An experiment was carried out on osmosis in carrot (Daucus carota) root tissue and potato (Solanum tuberosum) tuber tissue. Similar sized pieces of tissue were cut and soaked in different sucrose solutions for 24 hours. The results are shown in the graph below.
(a) Using the graph, estimate isotonic sucrose solutions for potato tissue and carrot tissue.
Potato:
Carrot:
(b) Suggest a reason for the difference in the isotonic points for the potato and the carrot tissues.
(c) From the evidence provided by the graph, evaluate the reliability of these data.
(d) Explain one reason for calculating the percentage change in mass.
2. The enzyme beta-galactosidase hydrolyses lactose to release glucose and fructose. A study was carried out to determine how acidity aff ects the activity of a beta-galactosidase enzyme, extracted from the fungus Penicillium simplicissimum.
(a) State another independent variable that would aff ect the activity of this enzyme.
(b) Outline the measurements which would need to be taken to determine the activity of the beta-galactosidase at diff erent pH values.
3. Pigments were extracted from spinach (Spinacia oleracea) leaves and separated on a thin layer chromatogram.
Removed for copyright reasons
(a) Describe how the spinach leaf pigment extract should be applied to a chromatogram so that the pigment bands separate clearly.
(b) State one advantage of using thin layer chromatograms over paper chromatograms.
(c) The chromatogram reveals that the spinach leaves contain a variety of coloured pigments. Explain the observation that spinach leaves appear green.
2019年11月IB生物SL真题余下省略！
你可能还关注