Grade 10
LIFE SCIENCES
Date: _____________
55 Marks
PRACTICAL
Energy in food
Examiner: T. Bell
Moderator: Z. Yaka
NAME:
PLEASE READ THE FOLLOWING INSTRUCTIONS CAREFULLY
1.
Write your name in the block above
2.
This paper consists of 6 pages. Please ensure that your question paper is
complete.
3.
Make sure to read the INFORMATION SHEET given, as this provides vital
information for you to complete your practical
4.
Read the questions carefully.
5.
Use the total marks which can be awarded for each question as an
indication of the detail required.
6.
It is in your interest to write legibly and to present your work neatly
7.
All laboratory safely regulations must be adhered to
8.
All work stations must be clean thoroughly after the practical is
complete
For teacher’s use only:
PRACTICAL SKILLS
PART A
/10
PART B
/44
TOTAL
/6
/60
You are going to investigate whether salivary amylase will break down starch
Before the practical begins, ensure that you have the following, either in at your work bench
or have access to them in the class:

3 test tubes

Starch powder

50 ml distilled water

Distilled water

2 wooden kebab sticks

Measuring spoon

Rinsing water

Litmus paper (red and blue)

Iodine

Plastic lid

10 ml syringe

Pipette dropper

Saliva

Paper towel

Sheet of white paper

Marker

Wall clock
Page 2 of 8
PART A – INVESTIGATION
1.
Label your test tubes A, B, C, and D respectively
2.
Measure 5 ml of starch powder and place in 50 ml of distilled water. Stir the contents
until powder is dissolved
3.
Using a clean syringe, add 10 ml of starch solution into test tubes A and B
4.
Using a clean syringe add 10 ml of distilled water into test tube C
5.
Add 5 drops of iodine solution into test tubes A, B, and C
6.
Swirl the contents of each test tubes gently
7.
Spit a few times into the empty lid
8.
Using litmus paper, determine whether the salvia is acidic, basic or neutral. Write your
answer in the space provided in the results table in Step 14
CALL YOUR INVIGILATOR TO CHECK YOUR PROGRESS BEFORE MOVING ON
9.
Note any colour changes in test tubes A, B and C in the results table in Step 15
10. Spit once into test tube B and C. Stir the contents with a kebab stick.
11. Wait 10 minutes, swirling test tubes A and B occasionally
12. While waiting, proceed to Step 16 and come back to your experiment after 10 minutes is
complete
13. After 10 minutes, record any colour changes in the table of results in Step 15
14. Record any colour changes in the results table below and provide a suitable heading for
the table where indicated:
Colour change
Red litmus paper
Blue litmus paper
Alkaline or Acidic
pH of saliva
(3)
Page 3 of 8
15. Heading: ___________________________________________________________
__________________________________________________________
Test tube
Colour before
iodine
Colour after
iodine
(2)
Colour change after
saliva
A
B
C
(8)
16. What was the aim of this experiment?
(2)
______________________________________________________________________
17. Suggest an appropriate hypothesis for this experiment.
(3)
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
18. Write a conclusion based on the results that YOU collected.
(2)
______________________________________________________________________
______________________________________________________________________
19. What is the dependent variable in the above experiment?
(2)
______________________________________________________________________
20. Give ONE control variable that was important for the fairness/success of this
investigation. State clearly how you went about controlling it.
(2)
______________________________________________________________________
______________________________________________________________________
21. If the test tubes were placed in a water bath at 60°C, what would you think would
happen to the rate of reaction of salivary amylase?
(2)
Page 4 of 8
______________________________________________________________________
______________________________________________________________________
22. The effect of temperature was investigated on the rate of human salivary amylase
activity. The following results were obtained:
Temperature (°C)
0
10
20
30
40
50
60
65
70
80
90
100
Rate of reaction
0
0
20
68
88
42
8
0
0
0
0
0
Plot a line graph of the above data on the grid provided on the next page
Page 5 of 8
.
(8)
23. Write the heading for your graph.
(2)
______________________________________________________________________
24. From your graph, what conclusions can you make about the effect of temperature on
salivary amylase?
(2)
______________________________________________________________________
______________________________________________________________________
25. What is the optimum temperature for salivary amylase?
(2)
______________________________________________________________________
[44 marks]
Page 6 of 8
PART B – Microscopy
1.
Below is a photomicrograph of a microorganism called Paramecium sp. Calculate the
true length of the microorganism along the dotted line, if the image was taken at
45 000X magnification. Give your answer in micrometres (ɥm).
(4)
1 mm = 1000 ɥm
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
2.
What is the difference between a cross section and a longitudinal section?
(2)
______________________________________________________________________
______________________________________________________________________
Page 7 of 8
3.
Draw a biological drawing of the Paramecium sp in question 1. All biological rules apply.
(6)
[12 marks]
Page 8 of 8