CONFIDENTIAL
- Specimen A-potato tissue-half @ student
- Specimen K-bread mould-growth duration-substrate-bread/ugali-5 days
- Hydrogen peroxide- 3 ml@ student
- Distilled water -4ml @ student
- Sodium hydroxide- 4ml @ student
- Dilute hydrochloric acid -4 ml @ student
- 10 ml measuring cylinder -1@ student
- Dropper
- Hand lens-shared
- Knife/scalpel-shared
- Mortar and pestle
- Spatula
- Ruler
- 100 ml beaker
- Source of heat
- Solution B-Starch solution
- Solution C1-UNBOILED amylase-4ml@ student.
- Solution C2-BOILED amylase
- Benedict’s solution.
- 5 test tubes@ student
- 5 labels @student
- Stop watch
- Iodine solution-shared
- Thermometer
Biology Paper 3 Questions
- You are provided with specimen labeled A. Obtain a cube measuring 1cm by 1cm from the specimen.
- Crush the cube using mortar and pestle, place the crushed parts in measuring cylinder, add 2 ml of hydrogen peroxide and quickly determine the volume of foam after 20 seconds and fill the table below. (1 mark)
Specimen Volume of foam Crushed cube A
Explain why the reaction in (a) above occurs in living cells. (2 marks) - You are provided with a solution labeled B, unboiled C1 and boiled C2. Place 2ml of the solution B into two test tubes and carry out a food test using the reagents provided. Record your observation in the table below. (2 marks)
FOOD
SUBSTANCEPROCEDURE OBSERVATION CONCLUSION
Place 2ml of solution B into four test tubes labeled F, G, H and K. Carry out the following steps.- To test tube labeled F and its contents add 3ml solution C1 and 3 ml distilled water.
- To test tube labeled G and its contents, add 3ml solution C1 and 3 ml dilute hydrochloric acid.
- To test tube labeled H and its contents, add 3 ml solution C 1 and 3 ml sodium hydroxide solution.
- To test tube labeled K and its contents, add 3 ml solution C2.
- Place the test tubes in a water bath at 37o C for 20 minutes.
- Carry out a Benedict’s test and fill the table below. (4 marks)
Test
tubePROCEDURE OBSERVATION CONCLUSION F G H K
- Account for the observation in:
- Test tube G. (2 marks)
- Test tube H. (1 mark)
- Test tube K. (2 marks)
- Crush the cube using mortar and pestle, place the crushed parts in measuring cylinder, add 2 ml of hydrogen peroxide and quickly determine the volume of foam after 20 seconds and fill the table below. (1 mark)
- Use the illustration below to answer questions
- Identify the organism from which the cell labelled B was obtained from while giving a reason.
- B. (1 mark)
- Reason. (1 mark)
- Give the functions of the parts labeled:
- R. (1 mark)
- S. (1 mark)
- Name the parts labeled:
- Q. (1 mark)
- P. (1 mark)
- K. (1 mark)
- Calculate the actual length of cell A in micrometers if its magnification Is X1000 000. Use the points marked L and X. (3 marks)
- Explain why cell A and B are believed to have a common ancestry. (2 marks)
- Identify the organism from which the cell labelled B was obtained from while giving a reason.
- Use the photographs below to answer questions
-
- Name the type of flowers shown in A1 and A2.
A1. (1 mark)
A2 (1 mark) - Describe the feature in flowering plants depicted in (a)(i) above. (1 mark)
- Explain how flower labeled A1 is modified for pollination. 1 mark)
- Name the type of flowers shown in A1 and A2.
- Give the functions of the parts labeled p, r and s in specimen labeled B.
- p. (1 mark)
- r. (1 mark)
- s. (1 mark)
- State the structural descriptions of flower B. (2marks)
- Explain what would happen to the following parts after pollination.
- t. (1 mark)
- u. (1 mark)
- You are provided with a specimen labeled K in a petri dish, observe the specimen using a hand lens and answer questions that follow.
- Make well labeled diagram to show the reproductive structure of the organism. (3 marks)
- Give the type of asexual reproduction exhibited by the organism. (1 mark)
-
Marking Scheme
- You are provided with specimen labeled A. Obtain a cube measuring 1cm by 1cm from the specimen.
- Crush the cube using mortar and pestle, place the crushed parts in measuring cylinder, add 2 ml of hydrogen peroxide and quickly determine the volume of foam after 10 seconds and fill the table below. (1 mark)
Specimen Volume of foam Crushed cube A Not more than 10 ml depending on concentration;1
Explain why the reaction in (a) above occurs in living cells. (2 marks)
Cellular respiration produce toxic hydrogen peroxide; enzyme catalase breaks down toxic hydrogen peroxide to harmless products; water and oxygen. - You are provided with a solution labeled B, unboiled C1 and boiled C2 in a boiling tube. Place 2ml of the solution into two test tubes and carry out a food test using the reagents provided. Record your observation in the table below. (2 marks)
FOOD SUBSTANCE PROCEDURE OBSERVATION CONCLUSION Starch; To 2ml of food substance in a test tube add 2 drops of iodine solution; Blue black; Presence of starch;
(award mark if all steps are correct)
Reducing sugars; 1/2 To 2ml of food substance, add equal amount of Benedict’s solution and boil mixture in water bath. Turns from blue to green to yellow to orange to brown; Presence of reducing sugars;
(award mark if all steps are correct)
Place 2ml of solution B into four test tubes labeled F, G, H and K. Carry out the following steps.- To test tube labeled F and its contents add 3ml solution C1 and 3 ml distilled water.
- To test tube labeled G and its contents, add 3ml solution C1 and 3 ml dilute hydrochloric acid.
- To test tube labeled H and its contents, add 3 ml solution C 1 and 3 ml sodium hydroxide solution.
- To test tube labeled K and its contents, add 3 ml solution C2.
- Place the test tubes in a water bath at 37 0C for 20 minutes.
- Carry out a Benedict’s test and fill the table below. (4 marks)
Test tube PROCEDURE OBSERVATION CONCLUSION F To 3ml of food substance, add equal amount of Benedict’s solution and boil mixture in water bath Turns from blue to green to yellow to orange to brown; 1/2 Presence of reducing sugars; 1/2 G To 2ml of food substance, add equal amount of Benedict’s solution and boil mixture in water bath Blue colour of Benedicts’s solution is retained. 1/2 Absence of reducing sugars; 1/2 H To 2ml of food substance, add equal amount of Benedict’s solution and boil mixture in water bath Turns from blue to green to yellow to orange to brown; 1/2 Presence of reducing sugars; 1/2 K To 2ml of food substance, add equal amount of Benedict’s solution and boil mixture in water bath Blue colour of Benedicts’s solution is retained. 1/2 Absence of reducing sugars; 1/2
- Account for the observation in:
- Test tube G. (2 marks)
Presence of reducing sugars, Enzyme is denatured by hydrochloric acid;starch not broken down to reducing sugars; - Test tube H. (1 mark)
Presence of reducing sugars, enzyme works best in alkaline condition; starch is broken down to reducing sugars. - Test tube K. (2 marks)
Absence of reducing sugars;enzyme is denatured;starch is not broken down to starch;
- Test tube G. (2 marks)
- Crush the cube using mortar and pestle, place the crushed parts in measuring cylinder, add 2 ml of hydrogen peroxide and quickly determine the volume of foam after 10 seconds and fill the table below. (1 mark)
- Use the illustration below to answer questions
- Identify the organism from which the cell labelled B was obtained from while giving a reason.
- B. (1 mark) Plant;
- Reason. (1 mark)
Cellulose cell wall;
Has chloroplast;
Nucleus at periphery;
- Give the functions of the parts labeled:
- R. (1 mark)
Site for respiration that yields energy for the cell; - S. (1 mark)
Synthesis of ribosomes;
- R. (1 mark)
- Name the parts labeled:
- Q. (1 mark)
Chloroplast; - P. (1 mark)
Nucleus/cell membrane; - K. (1 mark)
Smooth endoplasmic reticulum;
- Q. (1 mark)
- Calculate the actual length of cell A in micrometers if its magnification Is X1000 000.Use the points marked L and X. (3 marks)
Actual length =
drawing length;
Magnification
drawing length=7.6 +1 cm ,=760 mm=760 000 um;
760,000 ;
1000,000
=0.76 um; - Explain why cell A and B are believed to have a common ancestry. (2 marks)
Both have a nucleus;
Both have a nucleolus;
Both have a mitochondrion;
Both have endoplasmic reticulum; any 2
- Identify the organism from which the cell labelled B was obtained from while giving a reason.
- Use the photographs below to answer questions
-
- Name the type of flowers shown in A1 and A2.
A1 Staminate; (1 mark)
A2 Pistillate; (1 mark) - Describe the feature in flowering plants depicted in (a)(i) above. (1 mark)
Monoecism; - Explain how flower labeled A1 is modified for pollination. (1 mark)
Numerous to increase the surface area for attachment of pollen grains;
Hang outside to trap pollen grains;
- Name the type of flowers shown in A1 and A2.
- Give the functions of the parts labeled p, r and s in specimen labeled B.
- p. (1 mark)
Hold anthers in position; - r. (1 mark)
Receive pollen grains; - s. (1 mark)
Support the stigma; allow transfer of male gametes;any 1
- p. (1 mark)
- State the structural descriptions of flower B. (2marks)
Superior ovary;
Polypetalous;
polysepalous;
brightly coloured petals;
pedicillate; any 1 - Explain what would happen to the following parts after pollination.
- t. (1 mark)
Becomes pericarp; - u. (1 mark)
Becomes the seed;
- t. (1 mark)
- You are provided with a specimen labeled K in a petri dish, observe the specimen using a hand lens and answer questions that follow.
- Make well labeled diagram to show the reproductive structure of the organism. (3 marks)
- Give the type of asexual reproduction exhibited by the organism. (1 mark)
Sporulation ;
- Make well labeled diagram to show the reproductive structure of the organism. (3 marks)
-
Download Biology Paper 3 with Confidentials - 2020 MOKASA JOINT MOCKS EXAMINATION (QUESTIONS AND ANSWERS).
Tap Here to Download for 50/-
Get on WhatsApp for 50/-
Why download?
- ✔ To read offline at any time.
- ✔ To Print at your convenience
- ✔ Share Easily with Friends / Students