Beatty Answering Planning Questions for Practicals (ans) (edited)

Beatty Secondary School Secondary 4E Pure Biology Science Department Name : Register No : Class : Title : Answering Planning Questions for Practicals Date : 1 Planning questions in O level practicals: 1. usually 6 marks 2. usually can use the practical task that you have just completed during the exam to help you answer the planning question 3. usually requires you to include: a. Independent variable (variable that is being changed) e.g. concentration of salt or sugar solution/ temperature/ pH - 5 different concentrations/volumes/temperatures that are uniformly spaced. b. Dependent variable (variable being observed/measured) e.g. colour change/ time/Length/mass/volume c. Controlled variable (variable that is kept the same) e.g. Soaking time/ incubation time d. How data collected can be used to reach a conclusion e.g. plotting graph e. Using the result to conclude the experiment e.g. the concentration at which there is no change in mass is the concentration of the potato strip f. How to ensure reliability – e.g. repeat the experiment 3 times/ use two strips of potato for each concentration of solution

Secondary 3E Biology 2 Practical task 1: 1 (a) You are going to investigate the effect of two different concentrations of sucrose solution on potato tissue. You are provided with some potato tissue and two solutions of sucrose, labelled S1 and S2. • Label one petri dish S1 and the other petri dish S2. • Carefully cut two strips of potato tissue without skin, each measuring 50mm x 5 mm x 5mm. • Measure and record, in mm, the length of each strip in Table 1.1. • Place one strip into each petri dish. • Pour solution S1 into the dish labeled S1. Pour solution S2 into the dish labeled S2. Make sure the strips are completely covered by the solutions. • Leave the strips for 25 minutes. Continue with parts (c) and (d) of the practical during this time. • After 25 minutes, remove each of the potato strips and gently blot them dry on a piece of filter paper. Be careful to note which is strip S1 and S2. • Measure again the length of each strip and record your results in Table 1.1. [MMO] • Calculate and record in Table 1.1 the change in length of each strip. [PDO] Planning question: (b) (i) Outline an experiment you could carry out to investigate the cell sap concentration of the potato cells using potato slices. [P] independent variable: concentration of sucrose / salt solution (provide 5 different values] [1] controlled variable: diameter of potato slices and time of immersion 1. Cut 5 equal-sized sticks of potato from the same potato and measure initial diameter. 2. Put the pieces into 5 different concentrations of sucrose solution - 0%, 10%, 20%, 30%, 40%. [1] 3. Leave the slices for 25 min. [1] 4. Remove and blot the potato strips. measure final diameter for each sli