Biology Paper 3 Questions and Answers with Confidential - Form 4 End Term 2 Exams 2023

• Candidates should answer the questions in English.

1. You are provided with specimens J, K and L.
   1.  
      1. identify specimen J. (1mk)
      2. Give a reason for your answer in a) (i) above. (1mk)
   2. Using the scalpel provided, carefully make a cross section of specimen J.
      1. name the type of placentation (1mk)
      2. extract juice form specimen J and test it for vitamin C. (3mks)
         

         Food tested	Procedure	Observation	Conclusion

   3. Complete the table below using the specimens provided. (9mks)
      

      specimen	Agent of dispersal	One adaptation of the specimen
      J
      K
      L

2. The photographs below represents leaves from different plants.use them to answer the questions that follow.
   
   1. Each of the leaves A,B and C are modified to perform different functions. With a reason, state the functions. (10mks)
      

      LEAF	FUNCTION	REASON
      A
      B
      C

   2. State the type of evolution that may have led to the emergence of the different leaves shown in leaf A, B and C. (1mk)
   3. Name the type of evolution structure represented by the leaves above. (1mk)
   4. Name two examples of such structures as named in (b) (ii) above in aves. (2mks)
3. Below is a photomicrograph of a plant cell. Study it and answer the questions that follow.
   
   1.  
      1. Label the parts labeled R, S and T. (3mks)
      2. Name the chemical compound that constitutes part labeled R above. (1mk)
   2. State the function of part labeled 
      1. Q. (1mk)
      2. Nucleolus. (1mk)
   3. Below is an enlarged micrograph of organelle T.
      
      1. What is the function of organelle T.? (1mk)
      2. What is the biological significance of   having numerous parts U in organelle T.? (1mk)
   4. A student observed onion epidermal tissue using a microscope whose field of view was ____________mm in diameter as shown below. Calculate the approximate width of one of the cell. (3mks)
      

CONFIDENTIAL

In addition to the apparatus found in biology laboratory, each candidate should be provided with:

1. Ripe Yellow/purple passion fruit labeled specimen J.
2. Dry black jack fruit labeled K.
3. Fresh green peas/bean pod labeled specimen L.
4. Hand lens.
5. 3ml of DCPIP.
6. Dropper.
7. 50ml beaker.
8. Filter funnel.
9. Stirring rod.
10. One test tube.
11. Test tube rack.

MARKING SCHEME

1. You are provided with specimens J, K and L.
   1.  
      1. identify specimen J. (1mk)
         • Fruit;
      2. Give a reason for your answer in a) (i) above. (1mk)
         • Has two scars:
   2. Using the scalpel provided, carefully make a cross section of specimen J.
      1. name the type of placentation (1mk)
      2. extract juice form specimen J and test it for vitamin C. (3mks)
         
         

         Food tested	Procedure	Observation	Conclusion
         Vitamin C	Put DCPIP solution in a test tube then add juice drop by drop as you shake;	DCPIP declorisation;	Vitamin C present;

   3. complete the table below using the specimens provided. (9mks)
      
      

      specimen	Agent of dispersal	One adaptation of the specimen
      J	Animal;	-Brightly coloured; to attract the animal; -Fleshy/succulent; to attract the animals; -Slimy seeds with hard seedcoat; to resist digestion in the animals gut,hence released in feaces in viable state; -Scented; to attract animals;
      K	Animal;	-Has hooks; to attach to the animals fur/clothes; -Light; hence cannot be detected by the animal and thus be carried far distance;
      L	Self explosive mechanism	-Has satures/lines of weakness; in the pod along which they the pod breaks explosively throwing the seeds far away;

      (Mark 2mks for the adaptation.)
2. The photographs below represents leaves from different plants.use them to answer the questions that follow.
   1. Each of the leaves A,B and C are modified to perform different functions. With a reason, state the functions. (10mks)
      
      

      LEAF	FUNCTION	STORAGE
      A	Storage	Succulent/ swollen;
      B	Photosynthesis	Green in colour
      	Support	Has tendrils
      C	Photosynthesis	Its green;
      	Reproduction	has plantlets/buds;

   2. State the type of evolution that may have led to the emergence of the different leaves shown in leaf A, B and C. (1mk)
      • Divergent evolution;
   3. Name the type of evolution structure represented by the leaves above. (1mk)
      • Homologous structure;
   4. Name two examples of such structures as named in (b) (ii) above in aves. (2mks)
      • Beaks;
      • Legs;
3. Below is a photomicrograph of a plant cell. Study it and answer the questions that follow.
   1.  
      1. Label the parts labeled R, S and T. (3mks)
         • R – Cell wall;
         • S – Nucleus;
         • T – Mitochondrion; (rej plural)
      2. Name the chemical compound that constitutes part labeled R above. (1mk)
         • Cellulose;
   2. State the function of part labeled
      1. Q. (1mk)
         • Site for photosynthesis;
      2. Nucleolus. (1mk)
         • Manufacture ribosomes;
   3. Below is an enlarged micrograph of organelle T.
      1. What is the function of organelle T.? (1mk)
         • Site for respiration;
      2. What is the biological significance of   having numerous parts U in organelle T.? (1mk)
         • Increase surface area for attachment of more respiratory enzymes;
   4. A student observed onion epidermal tissue using a microscope whose field of view was ____________mm in diameter as shown below. Calculate the approximate width of one of the cell. (3mks)