Biology Paper 3 Questions and Answers with Confidentials - Form 4 End Term 1 Exams 2022

Questions

1. You are provided with an unknown mixture labelled J
   You are also provided with Benedict’s solution, dilute hydrochloric acid solution, iodine solution, Dichlorophenol-Indophenol (DCPIP) solution. Sodium hydrogen-carbonate solution, means of heating, test tubes, test tube holder and a test tube rack.
   1. Using the reagent provided only, test for the food substances in mixture J. Record inthe table below the chemical test, the procedure of the test, your observations and conclusions. 8mks
      

      Chemical test	Procedure	Observations	Conclusions

   2. Which of the components of mixture J does not undergo digestion in the mammalian digestive system? 1mk
   3.          
      1. Name a deficiency disease that may result from a deficiency of the component identified in (b) above. 1mk
   4. Name a common carbohydrate that could be present in mixture J. 1mk
   5. State the role of hydrochloric acid and sodium hydrogen carbonate in the experiment. 2mks
      1. Hydrochloric Acid
      2. Sodium Hydrogen Carbonate
2. The photographs below show a flower specimen. Study it carefully and use to answer the questions that follow.
   
   
   1. On the photograph, label the following parts 3mks
      1. Stigma
      2. Style
      3. Staminal tube
   2.     
      1. Classify the plant from which the flower was picked into the taxonomic groups listed below. 4mks
         1. Kingdom
         2. Division
         3. Sub division
         4. Class
      2. Name three observable features from the photograph of the class you named in (a) (i) above. 3mks
   3. Suggest the pollination agent of this flower. Give reasons for your answer.
      1. Pollinating agent 1mk
      2. Reasons 2mks
3. Below are photographs of two specimens, J and K. Both of them belong to the same Phylum and Class. Observe them carefully before you answer the questions that follow.
   
   
   1. Name the class to which J and K belong and support your answer with two reasons.
      
      1. Class 1mk
      2. Reasons 2mks
   2. Suggest why the transport fluid in J and K has no haemoglobin. 2mks
   3. The actual length of specimen K is 8cm, given that both J and K are under the same magnification, determine the actual length of J 3mks
   4. Below is a diagram showing the life cycle of specimen J.
      
      
      1. Identify the stage labeled D. 1mk
      2. Name the hormone responsible for the change from D to A. 1mk
      3. Explain the differences in the change from C2 to C3 and from C3 to D. 2mks
         1. C2 to C3
         2. C3 to D
      4. State the importance of the process illustrated above in the life cycle of the organism 2mks

Confidential

Candidates require the following in the working bench

QUESTION 1

1. Mixture J: Solution containing a mixture of sucrose and vitamin C.
2. Benedict’s solution,
3. Dilute hydrochloric acid solution.
4. Iodine solution
5. Dichlorophenol – indophenol (DCPIP) solution,
6. Sodium hydrogen – carbonate,
7. Means of heating,
8. 5 test tubes,
9. Test tube holder
10. Test tube rack

QUESTION 2

1. Photograph Q: complete hibiscus flower (Each candidate should be provided with a coloured photograph of hibiscus flower)

Marking Scheme

1. You are provided with an unknown mixture labelled J
   You are also provided with Benedict’s solution, dilute hydrochloric acid solution, iodine solution, Dichlorophenol-Indophenol (DCPIP) solution. Sodium hydrogen-carbonate solution, means of heating, test tubes, test tube holder and a test tube rack.
   1. Using the reagent provided only, test for the food substances in mixture J. Record in the table below the chemical test, the procedure of the test, your observations and conclusions. 8mks
      

      Chemical test	Procedure	Observations	Conclusions
      Non-Reducing Sugar	To about 2ml of solution J add 4drops of dilute HCl and heat .cool then add NaHCO3 solution dropwise until fizzing stops. Add Benedict’s solution and heat to boil.	Colour changes to yellow,orange,brown	Non-Reducing sugar present.
      Reducing sugar	To about 2ml of solution J add equal volume of Benedict’s solution. Shake the mixture and heat to boil.	Blue colour of Benedict’s solution remains	Reducing Sugar absent
      Vitamin C	To about 2ml of DCPIP add solution J dropwise	DCPIP is decolourised	Vitamin C present.

   2. vitamin C
   3.              
      1. Scurvy
   4. Sucrose
   5.                
      
      1. hydrolyseses the non-reducing sugars to the food substances into reducing sugars
      2. Neutralizes the hydrochloric acid
2.            
   
   1.                     
      1. Stigma
      2. Style
      3. Staminal tube
   2.             
      1.                             
         
         1. plantae           
         2. spermatophyta        
         3. angiospermae         
         4. dicotyledon         
            
            
      2.                  
         
         • broad network veined leaves
         • flowers
   3.                            
      1. insects
      2. Reasons 2mks
         • they are brightly coloured
         • large and conspicous
3.                               
   1.                               
      1. insecta
      2. Reasons 
         • 3 pairs of jined legs
         • presence of wings
         • Three body parts
                        
   2. insect-blood doesn’t transport respiratory gases,hence doesn’t contain haemoglobin
                     
   3. Actual length=    drawing length  
                              Magnification
      
      
   4.            .
      1. pupa
      2. moulting hormone
      3. Explain the differences in the change from C2 to C3 and from C3 to D. 2mks
         1. C2 to C3
            • this stage eats a lot, grows rapidly and sheds its cuticle several times
         2. C3 to D
            • this stage is inactive ,non-feeding stage
      4.                    
         • allows the insects to survive unfavourable conditions
         • larva occupies different niche from adult thus reducing competition.