Q1. (a) The diagrams show cells containing and surrounded by oxygen molecules. Oxygen can move into cells or out of cells.

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1 Q. (a) The diagrams show cells containing and surrounded by oxygen molecules. Oxygen can move into cells or out of cells. Into which cell, A, B, C or D, will oxygen move the fastest? Write your answer, A, B, C or D, in the box. () (b) Draw a ring around the correct word to complete each sentence. diffusion (i) Oxygen is taken into cells by the process of osmosis. respiration () breathing Cells need oxygen for photosynthesis. respiration () membranes (iii) The parts of cells that use up the most oxygen are the mitochondria. nuclei () Page of

2 diffusion (iv) Some cells produce oxygen in the process of photosynthesis. respiration () (Total 5 marks) Q2. The drawing shows the cell of a bacterium. (a) List A gives the four structures labelled on the diagram. List B includes information about each structure. Draw one line from each structure in List A to the correct information about the structure in List B. List A Structure List B Information (4) Page 2 of

3 (b) Give two differences between an animal cell and the cell of a bacterium (2) (c) The diagrams show cells containing and surrounded by oxygen molecules. Oxygen can move into cells or out of cells. Into which cell, A, B, C or D, will oxygen move the fastest? Write the correct letter, A, B, C or D, in the box. () (d) Complete the following sentence. Oxygen is taken into the cell by the process of... () (Total 8 marks) Page 3 of

4 Q3. Some students set up this experiment to investigate osmosis. They filled two pieces of dialysis [visking] tubing with different liquids and left them both in a beaker of 5% sucrose solution for an hour. (a) Describe and explain the likely results after one hour. (6) (b) Describe two examples where osmosis is used in living things. (2) (Total 8 marks) Page 4 of

Q4. Some students set up an experiment using osmosis to find the concentration of sucrose solution in potato cell sap. They used discs of potato cut to the same size and weighing approximately 0 gms.

5 Q4. Some students set up an experiment using osmosis to find the concentration of sucrose solution in potato cell sap. They used discs of potato cut to the same size and weighing approximately 0 gms. The discs were put into each of five beakers. (a) (i) After two hours they reweighed the discs after carefully blotting them first. Why did the students blot the potato before weighing it? () Their results are shown in the table below. Beaker Beaker 2 Beaker 3 Beaker 4 Beaker 5 Final mass in g Initial mass in g The students calculated the % gain or loss in mass of potato. Complete this table of results for Beakers 2, 4 and 5. Beaker Beaker 2 Beaker 3 Beaker 4 Beaker = =.0 = 0% Gain in mass = 30% Loss in mass = 0% (3) Page 5 of

6 (b) (i) Draw a graph of % Gain or Loss in mass against sucrose concentration. (3) Use the graph to find the concentration of potato cell sap. Concentration of cell sap =... % sucrose solution () (iii) Explain in terms of osmosis how you chose this value (2) (Total 0 marks) Page 6 of

7 M. (a) A (b) (i) diffusion respiration (iii) mitochondria (iv) photosynthesis [5] M2. (a) all four correct = 4 marks three correct = 3 marks two correct = 2 marks one correct = mark extra line from a statement cancels the mark 4 Page 7 of

8 (b) any two from: nucleus no cell wall separate chromosomes 2 (c) A (d) diffusion [8] M3. (a) award 3 marks per tube for each key idea for tube : expands or gets firmer or bigger or inflates it gains water because the concentration of water is less than its surroundings make sure answer is about water movement and not sucrose solution 3 for tube 2 gets floppy or flaccid or contracts it loses water because the concentration of water is greater than its surroundings 3 (b) any 2 from: uptake of water by root (hair) or movement from cell to cell within plant do not credit references to diffusion unless it is clear that the candidate is referring to the diffusion of water Page 8 of

9 guard cell function maintain turgor water absorption in the large intestine reabsorption of water from the nephron or collecting duct or in kidney or osmoregulation in kidney allow osmosis in other animals if some use is shown 2 [8] M4. (a) (i) change in weight was due to changes in potato or osmosis or not due to outside liquid ignore to make fair test beaker 2 = 5.(%) gain allow 5% beaker 4 = 2.8(5) loss not 2.7 allow 22% if no minus or no loss check graph beaker 5 = 29.8(%) loss allow 30% (b) (i) both axes correct values and scales > ½ of each axis ignore lack of minus signs on vertical axis points correct < ½ square allow answers in (a) line correct allow curve of best fit which can miss 0, 5 or straight lines between points do not allow one straight line or sketched line bar graph zero marks point where line crosses axis (eg 5-6% sucrose) allow point from candidate s graph ( 0.5%) Page 9 of

10 (iii) any two from: looking for understanding that water in equilibrium no change in mass not net movement of water or water entry and exit are equal because sucrose solution same concentration as cell sap or sucrose has same water potential as cell contents allow because the concentrations are the same (inside and out) 2 [0] Page 0 of

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The diagram shows four ways in which molecules may move into and out of a cell. The dots show the concentration of molecules.

The diagram shows four ways in which molecules may move into and out of a cell. The dots show the concentration of molecules. The cell is respiring aerobically. Which arrow, A, B, C or D, represents: (i)