An experiment was carried out to study the uptake of

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An experiment was carried out to study the uptake of substances A and B byamoeba. Itis known that amoeba takes up these two substances by different mechanisms.Amoebaewere placed in a solution with equal concentrations of substances A and B. Theexperimental set-up was kept at 15 ºC. The concentrations of substances A and B in thecytoplasm of theamoebawere measured at 30-minute intervals over a period of sixhours. The following graph shows the results.(a)Compare the uptake rate of substances A and B by theamoebaduring thesix hours.(4 marks)0123456Time(hours)Concentration incytoplasm (pg cm-3)02468101214Substance ASubstance BNote: 1 pg = 10–12g© 2019Aristo Educational Press Ltd.14
HKDSE BIOLOGY: Connecting ConceptsChapter 4Question bankStructured questions(b)According to the graph, state and explain the mechanism by whichamoebatakesup substance B.(4 marks)(c)If the temperature is increased to 25 ºC, what would you expect the uptake rate ofsubstance B to change? Explain your answer.(3 marks)(d)By what mechanism doesamoebatake up substance A?(1 mark)##
_________(12 marks)##Skills assessedMarks(a)Analysing data4© 2019Aristo Educational Press Ltd.15
HKDSE BIOLOGY: Connecting ConceptsChapter 4Question bankStructured questions(b)Analysing data1Applying concepts3(c)Applying concepts3(d)Analysing data1|!|BCELB0040000009|!|The water potentials of four plant root cells are shown in the table below. (kPa is a unitof pressure.)CellWater potential(kPa)A1800B2100C530D200The cells were placed in sucrose solution with a water potential of –530 kPa.(a)Which cell(s) would have a net uptake of water?(1 mark)(b)Which cell would initially take in water at the highest rate? Explain your answer.(3 marks)

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