Biology Paper 3 Questions and Answers with Confidential - Sunrise Pre Mock Exams 2023

INSTRUCTIONS TO CANDIDATES

• Answer all the questions.
• You are required to spend the first 15 minutes of the 1¾ hours allowed for the paper reading the whole paper carefully before commencing your work.

1. You are provided five with potato cylinders each measuring 5cm long, liquid S₁ and  S₂ , Hydrogen Peroxide, dilute Hydrochloric Acid, and test tubes labeled A,B and C.
   1.  
      1. Place one cylinder in a beaker containing liquid labeled S₁ and another in the liquid labeled S₂ . Allow to stand for 30 minutes, then remove the cylinders, wipe them dry using blotting paper. Measure each cylinder in centimeters and record their length and texture in the table given below. (4 marks)
         

         CYLINDER	LENGTH IN CM	TEXTURE
         LIQUID S1
         LIQUID S2

      2. Account for the results obtained in a (i) above (4marks)
   2.  
      1. Using a scalpel cut one of the cylinders into 5 parts each one centimeter long. Put the pieces into test tube A. Crush the other two using mortar and pestle into a paste. Divide the paste into two equal lots.
         Put one lot into test tube B and the other into test tube C.
         To each of the test tubes A and B add 2cm³ of hydrogen peroxide and to test tube C add 1 cm³ of dilute Hydrochloric Acid, then 2cm³ of hydrogen peroxide. Record your observation below.   (3marks)
         1. Test tube A
         2. Test tube B
         3. Test tube C
      2. Write a word equation for the reaction that occurs in the test tubes (1mark)
      3. Account for the rate of reaction in test tube A, B and C. (4 marks)
2. Below are sections of a dicotyledonous plant organs labeled X and Y.
   
   
   1. Give three observable differences between the sections. (3 marks)
   2. On the diagram, label any three parts of section Y. (3 marks)
   3. Identify and state the functions of the parts labeled A and B. (4 marks)
   4. How would section X compare with that of a monocotyledonous plant? (3 marks)
3. Study the photographs below and answer the questions that follow.
   1. Give two visible survival adaptive features for the organism in photograph X. (2 marks)
   2. Identify the dentitions exhibited in photograph Y and Z (2 marks)
   3. Study the photographs below showing a certain type of tooth and teeth arrangement in man.
      1. Label any three parts of the tooth in photograph S. (3 marks)
      2. Give two adaptations of the tooth to its function. (2 marks)
      3. Write the dental formula for the teeth arrangement in photograph T. (1 mark)

CONFIDENTIAL

1. Distilled water 4cm³ per student.
2. Salt solution 4cm³ per student.
3. Hydrogen peroxide.
4. Dilute HCL.
5. Raw potatoes one per student.
6. Stop watch.
7. Motor and pestle.

MARKING SCHEME

1.  
   1.  
      1.  
         

         CYLINDER	LENGTH IN CM	TEXTURE
         LIQUID S1	5.1 - 5.2	(very hard /stiff/firm)
         LIQUID S2	4.9 - 4.8	Soft /flabby/flexible

      2.  
         • S₁ has lower concerntration /lower osmotic pressure /hypotonic /more dilute than the cell sap of potato cells; water enters the potato cell by osmosis making the cells turgid /increasing the size of cells;
         • S₂ has higher concentration / higher osmotic pressure /hypertonic than cell sap of potato cells;water is lost from the cell by osmosis making them flaccid /decreasing the size of cels. (4marks)
   2.  
      1.  
         1. Test tube A ; less foam /bubbles /froth formed /slow effervescence /fizzing /frothing;
         2. Test tube B: more foam /bubbles /froth firmed //rapid effervescence /fizzing /frothing;
         3. Test tube C: little /small bubbles formed;               3marks
      2.                                    catalase
         Hydrogen peroxide  water + oxygen   1mark
      3.  
         1. Test tube A
            • The potato pieces provide a smaller surface area for enzyme action
         2. Test tube B
            • The crushed potato cylinder provides a larger surface area for enzyme action
         3. Test tube C
            • Dilute hydrochloric Acid alters /lowers the ph making it less favourable /suitable for enzyme catalase activity  (6marks)
2.  
   1.  
      

      X	Y
      Xylem in a ring	Xylem star shaped
      No root hair	Presence of root hair

   2.  
      
   3.  
      1. A Sclerenchyma;- Provide strength and support;
      2. B Cambium; –Give rise to new Xylem and new Phloem;
   4. In monocots, the vascular bundle is scattered in the ground tissue; No pith; No cambium;
3. Study the photographs below and answer the questions that follow.
   1. Give two visible survival adaptive features for the organism in photograph X (2mks)
      • Presence of ( large/long/curved) sharp/sharp pointed canine for piercing ;
      • Camouflage/blend well with environment concealing/hiding themselves from their predators/prey ;
      • Presence of fur to insulate against the low temperature
   2. Identify the dentitions exhibited in photograph Y and Z (2mks)
      1. Y - Heterodont
      2. Z - Homodont
   3. Study the photographs below showing a certain type of tooth and teeth arrangement in man.
      1. Label any three parts of the tooth in photograph S (3mks)
         
      2. Give two observable adaptations of the tooth to its function (2mks)
         • Broad surface to increase surface area for chewing
         • Cusps /ridges to increase surface area for chewing
      3. Write the dental formula for the teeth arrangement in photograph T (1mk)
         
         Reject
         • If Commas and capital letters are used in the dental formula
         • If Divisional line is missing in the dental formula