A pretest and post test 2024-2025 actual practical biology exam with complete questions
and answers (verified answers). Already graded A+
1.
(a)
Specimen Volume of foam
Crushed cube A More than 5 ml of form (depending on the concentration);
(b) Cellular respiration produces toxic hydrogen peroxide; enzyme catalase breaks down toxic
hydrogen peroxide to harmless products; water and oxygen gas;
(c)
FOOD PROCEDURE OBSERVATION CONCLUSION
SUBSTANCE
Starch To 2ml of solution B in a Presence of starch;
test tube add 2 drops of Blue black; (Award mark if all
iodine solution; acc food Acc blue-black steps are correct)
substance for solution B
Reducing To 2ml of solution B, add Turns from blue Presence of reducing
sugars equal amount of to green to sugars;
Benedict’s solution and yellow to orange (Award mark if all
boil mixture in water to brown; steps are correct)
bath; acc food Acc brown
substance for solution B colour observed
No mark is awarded if the procedure is wrong
TEST PROCEDURE OBSERVATION CONCLUSION
TUBE
F To 3ml of food substance, add Turns from blue to Presence of
equal amount of Benedict’s green to yellow to reducing sugars;
solution and boil mixture in water orange to brown;
bath;
G To 2ml of food substance, add Blue colour of Absence of
equal amount of Benedict’s Benedict’s solution reducing sugars;
solution and boil mixture in water is retained;
bath;
H To 2ml of food substance, add Turns from blue to Presence of
equal amount of Benedict’s green to yellow to reducing sugars;
solution and boil mixture in water orange to brown;
bath;
K To 2ml of food substance, add Blue colour of Absence of
equal amount of Benedict’s Benedict’s solution reducing sugars;
solution and boil mixture in water is retained.
bath;
One mark is awarded at the conclusion stage and only scored if the procedure and
observation are correct.
No mark is awarded if the procedure is wrong.
Account for the observation in:
(i) Absence of reducing sugars, enzyme is denatured by hydrochloric acid; starch not broken
down to reducing sugars;
(ii) Presence of reducing sugars, enzyme zworks best in alkaline condition; starch is broken
and answers (verified answers). Already graded A+
1.
(a)
Specimen Volume of foam
Crushed cube A More than 5 ml of form (depending on the concentration);
(b) Cellular respiration produces toxic hydrogen peroxide; enzyme catalase breaks down toxic
hydrogen peroxide to harmless products; water and oxygen gas;
(c)
FOOD PROCEDURE OBSERVATION CONCLUSION
SUBSTANCE
Starch To 2ml of solution B in a Presence of starch;
test tube add 2 drops of Blue black; (Award mark if all
iodine solution; acc food Acc blue-black steps are correct)
substance for solution B
Reducing To 2ml of solution B, add Turns from blue Presence of reducing
sugars equal amount of to green to sugars;
Benedict’s solution and yellow to orange (Award mark if all
boil mixture in water to brown; steps are correct)
bath; acc food Acc brown
substance for solution B colour observed
No mark is awarded if the procedure is wrong
TEST PROCEDURE OBSERVATION CONCLUSION
TUBE
F To 3ml of food substance, add Turns from blue to Presence of
equal amount of Benedict’s green to yellow to reducing sugars;
solution and boil mixture in water orange to brown;
bath;
G To 2ml of food substance, add Blue colour of Absence of
equal amount of Benedict’s Benedict’s solution reducing sugars;
solution and boil mixture in water is retained;
bath;
H To 2ml of food substance, add Turns from blue to Presence of
equal amount of Benedict’s green to yellow to reducing sugars;
solution and boil mixture in water orange to brown;
bath;
K To 2ml of food substance, add Blue colour of Absence of
equal amount of Benedict’s Benedict’s solution reducing sugars;
solution and boil mixture in water is retained.
bath;
One mark is awarded at the conclusion stage and only scored if the procedure and
observation are correct.
No mark is awarded if the procedure is wrong.
Account for the observation in:
(i) Absence of reducing sugars, enzyme is denatured by hydrochloric acid; starch not broken
down to reducing sugars;
(ii) Presence of reducing sugars, enzyme zworks best in alkaline condition; starch is broken
