Biology Paper 3 Questions and Answers with Confidentials - Mokasa II Mock Exams 2022

Questions

Instructions To Candidates

• Write your name and index number in the spaces provided at the top of this page.
• Answer all the questions in the spaces provided.

1. Study the specimen R provided.
   1. Identify the type of fruit. (1 mark)
   2.    
      1. What is the method of dispersal for the specimen R. (1 mark)
      2. Give reason(s) for your answer in (i) above (2 marks)
   3. Peel the sliced specimen R to show the inner juicy part. Extract a small portion of the juicy part, place in a mortar and mash it using a pestle.
      Filter the extract from the specimen R into a boiling tube.
      Divide the extract from specimen R into two portions and use them as follows;
      
      Portion one
      Use the reagents provided to test for the food substances present in portion 1. Use the table below as a guide. (6 marks)
      

      Food substance	Procedure	Observation	Conclusion

      
      Portion two
   4.      
      1. To 1cm³ of DCPIP in a test tube, add 0.1% solution of Ascorbic acid drop by drop until the colour of DCPIP disappears. Shake the test tube after addition of each drop. Record the number of drops used. (1 mark)
      2. To another 1cm³ of DCPIP in a test tube add the portion two of extract drop by drop, shaking the test tube after addition of each drop until the colour of DCPIP disappears. Record the number of drops used (1 mark)
      3. From the results obtained in (d) (i) and (ii) above, calculate the percentage of Ascorbic acid in the juice obtained from specimen R. Show your working (2 marks)
2. You are provided with photographs A, M and D representing certain plants and specimens P and Q .Use them to answer the questions that follow.
   
   
   1.  
      1. Name the sub division to which the plant in photograph A and specimen Q belong. (1 mark)
      2. Give a reason for your answer in a (i) above. (1 mark)
   2. State the differences between the leaves of specimen P and Q (3 marks)
      

      Specimen P	Specimen Q

   3. Name the unique features observed on stems of specimen Q and stem of photograph M and state their function. (2mks)
      Specimen Q
      Photograph M
   4. Account for the differences observed on the upper and lower surfaces of leaves on photograph D (2mks)
   5. The stem of specimen Q and that of photograph M are green in colour. What does the colour imply? (1mk)
   6.      
      1. Name the part labelled K on photograph labelled M (1mk)
      2. Explain how the coiling of the structure occurred (2mks)
3.   
   1. Use the photograph provided to answer the questions that follow.
      
      
      1. identify the bone (1mk)
      2. Give reason for your answer in (i) above (1mk)
      3. Name the region of the body from which the above bone was obtained (1mk)
      4. Name the bone which articulates with the above bone at its anterior end (1mk)
      5. Identify the type of joint formed in (iv) above (1mk)
      6. Name the structure that joins the two bones in c(i) together at the joint formed above (1mk)
      7. Identify the view of the above bone in the photograph (1mk)
      8. State two differences between the above bone and the bone it articulates with at the anterior end. (2mks)
   2.  
      1. Identify the bone in the photograph below (1mk)
         
      2. Name the structure labeled S and state the structure that it articulates with. (2mks)
      3. Name the structure labelled V and state its function (2mks)
      4. Name the part labelled M on the diagram (1mk)

Confidential

• Specimen R- a piece of ripe pineapple fruit
• 2mls Benedict’s solution placed in a test tube with a dropper
• 2mls of 10% Sodium hydroxide solution placed in a test tube with a dropper
• 2mls of 1% Copper sulphate solution placed in a test tube with a dropper
• Source of heat
• 4 test tubes in a rack
• 2 Droppers
• Scalpel/Razor blade
• Pestle and mortar
• Filter paper
• A funnel
• A boiling tube
• 4mls DCPIP solution placed in a small beaker with a dropper
• 4mls of 0.1% solution of Ascorbic acid supplied in a test tube
• White tile
• A twig of Lantana camara with flowerslabeled Q
• A twig of Tradescantialabeled P

Marking Scheme

1.      
   1. Pome
   2.    
      1. Animal
      2.    
         • Brightly coloured
         • Pleasant scent
         • Succulent /juicy
   3. 6mks)
      

      Food substance	Procedure	Observation	Conclusion
      Reducing sugars	Put 2ml of portion 1 into a test tube Add 2ml of Benedict’s solution Heat to boil	Color changes from blue ,green ,yellow ,orange	Reducing sugars present
      Proteins	Put 2ml of portion 1 into a test tube Add 2ml of Sodium hydroxide solution Add 3 drops of Copper Sulphateand shake after each drop	Blue colour is retained	Proteins absent
      Vitamin C/Ascobic acid	To 2ML of DCPIP add food sample drop wise	DCPIP decolourised	Vitamin C present

   4.    
      1.  4 drops
      2. Should be more than 4 drops
      3. 0.1 x 4 drops
         drops in d (ii)
2. You are provided with photographs A, M and D representing certain plants and specimens P and Q .Use them to answer the questions that follow.
   1.        
      1. Name the sub division to which the photograph A and specimen Q belong. (1 mark)
         • Angiospermaphyta;/acc.Angiospermae Reject if does not begin with capital letter
      2. Give a reason for your answer in a (i) above. (1 mark)
         • They are flower bearing
   2. State the differences between the leaves of specimen P and Q (3 marks)
      

      Specimen P	Specimen Q
      Network venation	Parallel venation
      Rounded apex	Pointed apex
      Margins are Serrated	Margins entire
      Broader	Slender

   3. Name the unique features observed on stems of specimen Q and stem of photograph M and state their function. (2mks)
      
      1. Specimen Q
         • Presence of spines
         • Prevents herbivores from feeding on it.
      2. Photograph M
         • Hairy stem
         • Traps a layer of moisture preventing excessive loss of water vapour
         • Tendrils
         • Support
   4. Account for the differences observed on the upper and lower surfaces of leaves on photograph D (2mks)
      • Upper surface is (dark) green while lower surface is white/light grey; chloroplasts are concentrated on the upper surface to trap maximum light for maximum photosynthesis. The light grey lower surface is due to numerous epidermal hairs to reduce transpiration.
   5. The stem of specimen Q and that of photograph M are green in colour. What does the colour imply? (1mk)
      • Have chloroplasts for photosynthesis
   6.  
      1. Name the part labelled K on photograph labelled M (1mk)
         • Tendril
      2. Explain how the coiling of the structure occurred (2mks)
         • Contact on solid object causes lateral diffusion/migration of auxins away from point of contact, higher concentration of auxins at the point away from contact causes faster/rapid cell division and elongation and thus coiling.
3.   
   1. use the photograph provided to answer the questions that follow.
      1. identify the bone (1mk)
         • Axis
      2. Give reason for your answer in (i) above (1mk)
         • it has odontoid process
      3. Name the region of the body from which the above bone was obtained (1mk)
         • Neck region
      4. Name the bone which articulates with the above bone at its anterior end(1mk)
         • Atlas
      5. Identify the type of joint formed in (ci) above (1mk)
         • Pivot
      6. Name the structure that joins the two bones in c(i) together at the joint formed above (1mk)
         • ligaments
      7. Identify the view of the above bone in the photograph (1mk)
         • Dorsal
      8. State two differences between the above bone and the bone it articulates with at the anterior end.(2mks)
         

         Atlas	Axis
         Has the articulating facet that articulates with occipital condyles	Lacks the articulating facets
         Lacks odontoid process	Has odontoid process

   2.    
      1. Identify the bone in the photograph below (1mk)
         • Pelvic girdle
      2. Name the structure labelled S and state the structure that it articulates with. (2mks)acetabulum
         • Head of femur
      3. Name the structure labelled V and state its function (2mks)
         • Pubis symphysis
      4. Name the part labelled M on the diagram (1mk)
         • Widens to allow parturition