Biology Paper 3 Questions and Answers with Confidential - Form 4 Term 3 Opener Exams 2023

• Answer all the questions in the spaces provided
• Candidates should answer the questions in English.

1.  You are provided with specimen Q 
   1.  
      1. Identify main part of the specimen                              (1mk)
      2. State the functions of the part named in (a) (i) above                      (2mks)
   2. Using a surgical blade provided, cut a cube of 2cm x 2cm x 2cm; grind; add 3mls of distilled water, stir, then filter the paste. Using the filtrate test the foods present using the reagents provided.                                                                                                      (8mks)
      

      Food	Procedure	Observation	Conclusion

   3. You are provided with specimen R and S 
      1. Write down any two similarities between specimen R and S                                  (2mks)
      2. Tabulate any two differences between specimen R and S                                     (2mks)
      3. Using a blade provide; carefully make transverse section of specimen S.
         Make a labelled diagram of the cut section. Label any three parts.             (4mks)
      4. Name the type of placentation                               (1mk)   
2. Study photographs shown below then answer the questions.
   
   1. State the type of evolution represented by structures Q1, R1 and S1. (1mk)
   2. Explain the type of evolution identified in (a) above. (1mk)
   3. Give the evolution term used to describe structures;
      1. Q1, R1 and S1. (1mk)
      2. A1, B1 and C1. (1mk)
   4.  
      1. Name classes for organisms labeled Q, R and S.   (3 mks)
      2. Give two reasons for placing S in the class above                                   (2mks)
   5.  
      1. Suggest the diet of animals B and R.        (2 mks)
      2. How is beak of animal B adapted to its function?                        (2mks)
3. Study the photomicrographs of cells below and answer the questions given.
   
   1. Name the parts labeled. (3mks)
      1. Q
      2. R
      3. U
   2. What is the function of
      1. Organelle Q. (1mk)
      2. Golgi bodies. (2mks)
   3. How is organelle T adapted to its function? (1mks)

CONFIDENTIAL

Each candidate should be supplied with the following: -

• Specimens Q.- A carrot without leaves
• Specimens R – maize grain
• Specimens S –Ripe orange fruit with remains of sepals.
• Surgical blade.
• Mortar & pestle.
• Two spatulas of sand
• Spatula
• 2 test tubes
• Test tube rack
• 2 labels
• Benedicts solution with dropper.
• Means of heating;
• Test tube holder
• Filter funnel
• Thro filter papers
• Distilled water
• Measuring cylinder (10mls)

MARKING SCHEME

1. You are provided with specimen Q
   1.  
      1. Identify main part of the specimen                              (1mk)
         • (Tap) root
      2. State the functions of the part named in (a) (i) above                      (2mks)
         • It provides support
         • It absorbs water; and mineral salts;
         • It stores food;
   2. Using a surgical blade provided, cut a cube of 2cm x 2cm x 2cm; grind; add 3mls of distilled water, stir, then filter the paste. Using the filtrate test the foods present using the reagents provided.              (8mks)
      

      Food	Procedure	Observation	Conclusion
      Reducing Sugar	To the filtrate In test tube, add equal Amount of Benedicts Solution then heat/warm;	The filtrate changes colour from blue, to green, yellow and finally orange;	Reducing  Sugar Present;
      Vitamin c/ Ascorbic        Acid,	Put  DCPIP in a test tube, drop by drop add the filtrate;	The solution  remains blue;	There is absence of Vitamin  C

   3. You are provided with specimen R and S
      1. Write down any two similarities between specimen R and S                                  (2mks)
         • Both have two scars/both are fruits;
         • Both have stored food;
         • Both formed after fertilization/double fertilization;
         • Both dispersed by man.
      2. Tabulate any two differences between specimen R and S                                     (2mks)
         

         R	S
         Not fleshy  Has the ability to germinate when sown  Its white/creaming colour  Is scented  Has no remains of sepal  It feels hard	Its fleshy/succulent/juicy Has no ability to germinate when sown Its orange in colour Not scented; Has remains of sepal It feels spong

      3. Using a blade provide; carefully make transverse section of specimen S. Make a labelled diagram of the cut section. Label any three parts.             (4mks)
         Label 2mks
         Proportionality 1
         Magnification 1mk
         Continuous outline 1mk
         Max 4mks
      4. Name the type of placentation                               (1mk)   
         • axile                                     
2. Study photographs shown below then answer the questions.
   1. State the type of evolution represented by structures Q1, R1 and S1. (1mk)
      • Convergent evolution
   2. Explain the type of evolution identified in (a) above. (1mk)
      • Different structures with different embryonic origins are modified to perform similar functions
   3. Give the evolution term used to describe structures;
      1. Q1, R1 and S1. (1mk)
         • Analogous structures
      2. A1, B1 and C1. (1mk)
         • Homologous structures
   4.  
      1. Name classes for organisms labeled Q, R and S.
         • Q  -   Insecta;               (1mk)
         • R  -   aves             (1mk)
         • S  -    mammalia         (1mk)
      2. Give two reasons for placing S in the class above                        (2mks)
         • Body covered with hair/fur
         • Has mammary glands
         • Has external ears/pinna
   5.  
      1. Suggest the diet of animals B and R.
         • B - flesh                   (1mk)
         • R  -  nectar from flowers         (1mk)
      2. How is beak of animal B adapted to its function?                        (2mks)
         • Strong, curved and sharp; to rip flesh from bones.
3. Study the photomicrographs of cells below and answer the questions given.
   1. Name the parts labeled. (3mks)
      1. Q – Chloroplast;
      2. R – Cell wall;
      3. U- Cristae;
   2. What is the function of
      1. Organelle Q. (1mk)
         • Site for photosynthesis;
      2. Golgi bodies. (2mks)
         • Package and transport glycoproteins;
         • Transport of synthesized materials out of the cell as secretions;
         • Section of synthesized  proteins and carbohydrates;
         • Form lysosomes;
   3. How is organelle T adapted to its function? (1mks)
      • inner membrane folded into cristae to increase surface area for attachment of respiratory enzymes;
      • matrix have numerous enzymes to catalyse respiratory reactions;