Biology Paper 3 Questions and Answers with Confidential - Momaliche Post Mock 2020 Exam

Instructions to candidate

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

Questions

1. You are provided with specimens labelled A and B. Examine the specimens and answer the questions that follow.
   1. With a reason state the type of germination in each of the specimens. (4 marks)
      Specimen A. Type of germination:
      Reason:
      Specimen B. Type of germination:
      Reason: 
   2. Draw a well labelled diagram of specimen B. (5 marks)
   3. Using observable features only state the class to which each of the specimens belongs. (4 marks)
      Specimen A. Class:
      Reason:
      Specimen B. Class:
      Reason: 
2. You are provided with a specimen labeled T which is a fruit. Use it to answer the questions that follow.
   
   1. Make a transverse section of the specimen T. Draw and label at least 3 parts. 6mks
   2. With reasons, state the identity of fruit
      Type of fruit 1mk
      Reason 1mk
   3. Suggest the possible agent of dispersal and give two reasons
      Agent 1mk
      Reason 2mk
   4. What is the placentation of T? 1mk
   5. Specimen T was green in colour before it was treated with a plant hormone.
      Suggest the plant hormone. 1mk

3. You are provided with a specimen labeled N. Squeeze the contents of N into the test tube. Add  of water and shake the contents. Reserve the piece of intestine for question (b)
   1. Use the reagents provided to test for the presence of various food substances in N extract. Record your observations in the table below (6mks)
      

      Food substance tested	Procedure	Observation	Conclusion

   2. Account for the results obtained in (a) above. (2marks)
   3. Cut specimen N along its length to expose the inner surface (2marks)
      
      1. Compare the inner and outer surface of the specimen. Record your observations. (2marks)
      2. Account for your observation of the inner surface. (2marks)

MARKING SCHEME

1. 1. Specimen A. Type of germination: Hypogeal;
      Reason: Cotyledons remain underground during germination;
      Specimen B. Type of germination: Epigeal;
      Reason: Cotyledons raised above the ground level during germination;
   2. 
      
      Drawing 1 mark(Check Accuracy /continuous outline/proportionality);    Labelling 4 marks
   3. Specimen A. Class: Monocotyledonae;
      Reason: Leaves have parallel venation; one cotyledon/seed leaves; Fibrous root system; Any one
      Specimen B. Class: Dicotyledonae;
      Reason: Leaves have network /reticulate venation; two cotyledons/seed leaves; Tap root system; Any one
2.  
   1.                              5mks
      
      Magnification between X1 and X5 
   2. Type of fruit   Berry 1mk
      Reason has many seeds 1mk
   3. Agent       Animal 1mk
      Reason     brightly coloured; scented; fleshy; large; first 2mk
   4. Axile;  1mk
   5. Ethylene/ ethyne; 1mk
3.  
   1. 
      

      Food substance	Procedure	Observation	Conclusion
      starch	To 1cm³ of the solution add 2 drops of iodine solution     1	Iodine colour is retained        1	Starch absent      1
      Protein	To  of the solution add an equal amount of sodium hydroxide followed by 2 drops of CuSO4     1	Purple colour          1	Proteins present       1

   2. Proteins present because their digestion is incomplete;
      no starch because it has been digested/hydrolyzed into reducing sugars; max 2 mks
   3. Inner surface has finger- like projections therefore it is rough and waxy; slimy/mucus; max 2mks
   4. Finger-like projections are villi which increase surface area for absorption of digested food;
      mucus/slimy to prevent it’s wall from being digested by digestive enzymes;mucus lubricates the food;max 2mks

BIOLOGY PAPER 3 PRACTICAL REQUIREMENTS

1. Besides other laboratory fittings and equipment, each candidate will require the following:
   
   • A germinated maize seedling (with the first foliage leaves) labelled A
   • A germinated bean seedling (with the first foliage leaves) labelled B
2. Each candidate should have:
   Scalpel/blade
   One ripe banana
   Scalpel/blade

3. Iodine solution
   Dilute sodium hydroxide solution
   1 % copper (II) sulphate
   Boiling tube
   3 test tubes
   Distilled water
   N- Small intestine of a cow5cm for each student. (Inner contents should intact)