SAMPLE QUESTION 1
You have been provided with solution N and five (5) test tubes labelled T, U, V, W and X.
i. Pour about 2cm3 of solution N in a test tube labelled T; add three drops of iodine solution. Shake well and record your observation.
ii. Pour about 2cm3 of solution N into a test tube labelled U; add an equal volume of Benedict’s solutions. Heat gently to boiling point and record your observation.
iii. Pour about 2cm3 of solution N into a test tube labelled V; add a few drops of Sudan (III) solution. Shake well and leave the mixture to stand for about 3 minutes. Record your observation.
v Pour about 2cm3 of solution N into a test tube labelled W; add a few drops of sodium hydroxide (NaOH) followed by a dropwise addition of copper (II) sulphate solution. The mixture was well shaken after each drop of copper (II) sulphate solution. Record your observation.
iv. Pour about 2cm3 of solution N into a test tube labelled X; add a few drops of dilute HCl acid; heat the mixture and let it cool. Add a few drops of Sodium Hydroxide followed by addition of an equal amount of Benedict’s solution. Heat gently to boiling point and record your observation.
(a) (i) What are the observations in each step?
(ii) What does each step suggest?
(b) Among the foods tested which one is digested first (before others). State where the elementary canal is
(i) That food digested
(ii) The enzyme involved
(iii) The end products
(c) Mention at least two natural sources of each identified food substance
SAMPLE QUESTION 2
2. You are provided with solution S1 containing an unknown food substance, design and carry out an experiment to identify the food substance present in solution S1 and record your experimental work as in the table having the following
- Food Tested
- Procedure
- Observation
- Inference
b) (i) State the reason(s) why animals need food substances identified in solution S1
(ii) Explain the process taking place in the liver which enables the body to excrete one of the food substances mentioned (a) above.
c) Mention four sources for each food mentioned in (a) above.
d) Name the site of the alimentary canal in which the food identified in (a) above is digested.
e) Mention the enzyme and end product of the food substance mentioned in (a) above.
f) Why the enzymes which digest protein cannot digest starch?
SAMPLE QUESTION 3
Read the practical details carefully and then answer the following questions: You have been provided with a piece of raw cassava and a rubber band.
Take a piece of raw cassava, cut it into small pieces and grind it using a mortar and pestle. Then added 30cm3 of cold water, decant the mixture into a beaker, and label the beaker "Cassava extract" or C.
Take a rubber band into your mouth and chew it so as to produce saliva, collect about 10cm3 of saliva in another beaker, add 5cm3 of water, stirred the mixture, and label the beaker "Saliva solution" or S.
Then perform the following experiments:-
Experiment 1
Pour about 2 cm3 of the cassava extract into the test tube and test for the presence of carbohydrates.
Experiment 2
Pour about 2 cm3 of saliva solution; add 2cm3 of cassava extract in a test tube. Leave the mixture to stand for 3 minutes, and then test for the presence of carbohydrates.
Experiment 3
Pour about 2 cm3 of cassava extract into the test tube and boil it for 3 minutes allow it to cool, and then test for the presence of carbohydrates.
Experiment 4
Pour about 2 cm3 of cassava extract into the test tube and boil it for 3 minutes allow it to cool, add 2 cm3 of saliva solution and after 3 - 5 minutes, test the mixture for the presence of carbohydrates.
a) Present your experimental work for experiments 1 to 4 in a table form based on the guidelines below
c) Explain the difference in observations between experiments 2 and 4.
Take a piece of raw cassava, cut it into small pieces and grind it using a mortar and pestle. Then added 30cm3 of cold water, decant the mixture into a beaker, and label the beaker "Cassava extract" or C.
Take a rubber band into your mouth and chew it so as to produce saliva, collect about 10cm3 of saliva in another beaker, add 5cm3 of water, stirred the mixture, and label the beaker "Saliva solution" or S.
Then perform the following experiments:-
Experiment 1
Pour about 2 cm3 of the cassava extract into the test tube and test for the presence of carbohydrates.
Experiment 2
Pour about 2 cm3 of saliva solution; add 2cm3 of cassava extract in a test tube. Leave the mixture to stand for 3 minutes, and then test for the presence of carbohydrates.
Experiment 3
Pour about 2 cm3 of cassava extract into the test tube and boil it for 3 minutes allow it to cool, and then test for the presence of carbohydrates.
Experiment 4
Pour about 2 cm3 of cassava extract into the test tube and boil it for 3 minutes allow it to cool, add 2 cm3 of saliva solution and after 3 - 5 minutes, test the mixture for the presence of carbohydrates.
a) Present your experimental work for experiments 1 to 4 in a table form based on the guidelines below
- Experiment
- Test for
- Procedure
- Observation
- Inference
c) Explain the difference in observations between experiments 2 and 4.
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