Biology Paper 3 Questions and Answers with Confidentials - Bondo Joint Mocks Exams 2022

Questions

Instructions to candidates:

•  Answer all the questions in this paper.
• You are required to spend the first 15 minutes of the 1¾ hours allowed for this paper reading the whole paper carefully.

1. You are provided with specimens labelled A which were soaked overnight
   1.      
      1. Name the part a plant represented by the specimens (1 mark)
      2. Give a reason for your answer in a) (i) above (1 mark)
   2. State three roles of water in germination of the specimens (3 marks)
   3. Using a scapel, cut a longitudinal section of specimen. Draw and label the section (4 marks)
   4.      
      1. Name the division to which the specimens were obtained belongs (1 mark)
      2. Name the part of the flower that forms the specimen (1 mark)
2.  
   1. Crush the cotyledons of specimen A in a mortar and pestle into a fine paste. Add enough water to make a solution
      Use the reagents provided to test for food substances in the solution of the cotyledons.
      Record the food substances, procedure, observation and conclusion in the table below.
      (12marks)
      

      FOOD SUBSTANCES	PROCEDURE	OBSERVATION	CONCLUSION

   2. Name the enzyme that would digest the food substances present in the cotyledons in the human:
      1. Mouth (1 mark)
      2. Stomach (1 mark)
3. You are provided with specimen X, Y, Z and a photograph W
   1. In the table below name the type of fruit, mode of dispersal and the features that adapt the specimen(s) to that mode of dispersal. (12 marks)
      

      Specimen	Type of fruit	Reason	Mode of dispersal	Adaptation to dispersal
      X
      Y
      Z

   2. Study the photograph below:
      
      
      1. State the type of placentation in specimen W? (1 mark)
      2. Why is specimen W regarded as a fruit and not a seed? (1 mark)
      3. State one difference between specimen X and Z (1 mark)

Confidential

Each Candidate Will Require The Following:

• specimen X black jack fruit
• specimen Y Sonchus
• Specimen Z Pea pod
• Means of grinding (pestle and mortar)
•  Iodine solution in access
• Dropper
• 10% Sodium Hydroxide solution in access
• 1% Copper (II) sulphate in access
• Benedict’s solution
• Source of heat
•  Test tube holder
• Three test tubes
• Scalpel/ Razor blade
• Hand lens
•  3 mature bean seeds soaked in water for 2 days labelled specimen A
• 10 ml Measuring cylinder

Marking Scheme

1.      
   1.      
      1. A seed; (1 mark)
      2.  has one scar; (1 mark)
   2. Any first three(3 marks)
      • Dissolves the hydrolysed food substances;
      • Transports soluble food substances to the embryo/growing regions/ plumule and radical;
      • Softens the testa to allow emergence of the radical;
      • Hydrolyses the stored food substances;
      • Activates the enzymes;(which begin the breakdown of the stored food substances;
      • Acts as a medium for enzyme action;
   3.      
      
   4.       
      • Spermatophyta;
      • Ovule; accept ovules
2.             
   1. (12 marks)
      

      FOOD SUBSTANCES	PROCEDURE	OBSERVATION	CONCLUSION
      Starch;	- To 2cm3 the food sample in the test tube - Add 3 drops of iodine solution and shake ;	Blue black colour;	Starch present;
      Proteins;	- To 2cm 3 of the food sample in the test tube  - Add 2cm 3 of 10% Sodium Hydroxide and shake - Add 1% Copper(II) sulphate drop wise and shake;	Purple colour colour ;	Proteins present
      Reducing sugar;	- To 2cm 3 the food sample in the test tube - Add 2cm 3 of Benedict’s solution and heat to boil;	Blue colour of Benedict’s solution persists;	Reducing sugars absent;

   2.      
      1. Salivary Amylase/Ptyalin; (1 mark)
      2. Pepsin; (1 mark)
3.      
   1. . (12marks)
      

      Specimen	Type of fruit	Reason	Mode of dispersal	Adaptation to dispersal
      X	Cypsela;	Persistent calyx;	Animal;	Presence of hooks for attachment to fur/clothing;
      Y	Cypsela	Pappus of hairs;	Wind;	Hair like projections /pappus of hairs to increase surface area to be carried by air ;
      Z	Legume/Pod;	Fruit wall not differentiated/presence of lines of weakness/sutures;	Self explosive mechanism;	presence of lines of weakness/sutures which splits open/dehisces;

       
   2.  
      1. (1 mark)
         • Axile/central; (1 mark)
      2. X is indehiscent while Z is dehiscent/X does not split open while Z splits open; (1 mark)