Biology P3 Questions and Answers - Butula Sub-County Post Mock Exams 2021/2022

INSTRUCTIONS TO CANDIDATES

1.  Answer all the questions.
2. Spend the first 15 minutes of the 1 ¾ hours allowed for this paper reading the whole paper carefully before commencing your work.
3. Answers MUST be written in the spaces provided in the QUESTION PAPER ONLY.
4. This paper consists of 12 printed pages. Candidates should check the question paper to ensure that all pages are printed as indicated and no questions are missing

QUESTION

1. You are provided with the following materials and reagents. A straight portion of raw banana, labelled D
   Two petri dishes, a scalpel/sharp razor blade, two beakers containing solution A and B ,A stop watch/access to a wall clock, Means of labeling
   1. Label the two petri dishes, A and B
   2. Fill petri dish A with solution A and petri dish B with solution B
   3. Using the scalpel, prepare four thin, straight flat strips from the raw banana peel
   4. Each strip should measure about 4cm by 2mm as illustrated below
      
   5. Immerse two strips in petri dish A and the other two in petri dish B and leave the set ups undisturbed for 10 minutes.
      1. State your observations in petri dish A and B after 10 minutes
         Petri dish A (1mk)
         Petri dish B (1mk)
      2. Account for the observations made in (a) (i) above
         Petri dish A (3mks)
         Petri dish B (3mks)
      3. With reference to the observations made, compare the nature of the outer and inner surfaces of the pawpaw peel (2mks)
         

         OUTER SURFACE	INNER SURFACE

      4.                                
         1. Name the cell structure responsible for the observations made in this experiment (1mk)
         2. Explain how the cell structure named in (d) (i) above works to bring about the observations made (1mk)
2. Study the specimens provided then answer the questions below.
   
   
   1. Name the parts labeled U1, W1, W2 and V3 (4mks)
      U1…………………………………………………………………………………………
      W1…………………………………………………………………………………………
      W2…………………………………………………………………………………………
      V3…………………………………………………………………………………………
   2.                    
      1. Suggest the mode of dispersal of the specimen labeled U (1mk)
      2. Give a reason for your answer in b (i) above. (1mk)
   3.                        
      1. suggest the mode of dispersal of the specimen labeled X. (1mk)
      2. Give a reason for your answer in C (i) above (1mk)
   4. The Photograph shown below was taken from a damp tree bark. It has organism Q on the surface. Study it then answer the questions.
      
      
      1. Name organism labeled Q (1mark)
      2. Name two organisms that make up Q (2marks)
      3. Suggest the feeding relationship between the identified organisms in d (i) above (1mark)
      4. Identify the two possible Kingdoms represented by organism Q. (2marks)
3. Study photographs shown below then answer the questions.
   
   
   1. State the type of evolution represented by structures Q1, R1 and S1. (1mark)
   2. Explain the type of evolution identified in (a) above. (1mark)
   3. Give the evolution term used to describe structures;
      1. Q1, R1 and S1. (1mark)
      2. A1, B1 and C1. (1mark)
   4. What type of evolution is illustrated by the limbs (A1, B1 and C1)? (1mark)
   5.                    
      1. Name class for organisms labeled Q, R and S.
         Q (1mark)
         R (1mark)
         S (1mark)
      2. Give two observable reasons for your answer for class S. (2marks)
   6.                      
      1. suggest the diet of animals B and R.
         B (1mark)
         R (1mark)
      2. How is beak of animal B adapted to its function? (2marks)

MARKING SCHEME

1.                    
   1. Petri dish A- strip curves towards the epidermis/epicarp with mesocarp outside/ curve outwards; reject: cortical cells
      Petri dish B- The strip curve inwards/ the strip curves towards the mesocarp (with the epicarp outside) . reject: cortical cells
      Accept: labelled diagram for explanation
   2. Petri dish A-solution A is hypotonic to the cell sap of the banana; the mesocarp cells gained water by osmosis; become turgid/ increased in length; hence the curvature; epidermal cells/epicarp did not gain water because of water proof cuticle
      Mark first 3
      Petri dish B- solution B is hypertonic to the cell sap of the banana; the mesocarp cells lost water by osmosis; shrink and become flaccid/ decreased in length; hence the curvature; epidermal cells/epicarp did not gain water because of water proof cuticle Mark first 3
   3.                                      
      
      

      Outer surface	Inner surface
      Waxy	Not waxy
      Non- cellular	Cellular
      Transparent	Not transparent
      Thin	Thick

   4.                    
      1. Cuticle;
      2. It is waterproof hence restricting gaining /losing of water
2.                    
   1. U1- Funicle
      WI- Mesocarp.
      W2- Seed. Reject seeds
      V3- Placenta.
   2.                      
      1. Self- dispersal.
         N/B: Reject wrong spelling.
      2. Presence of line of weakness/ sutures.
   3.                        
      1. Animal dispersed
      2. Presence of hooks for attachment on the animal skin/ fur or cloth.
   4.                      
      1. Organism Q- Lichen
      2. Blue green algae Acc Algae Fungus
      3. Symbiosis
      4. Kingdom Fungi
         Kingdom Protista/ Protoctista First letters should be capital
3.                          
   1. Convergent evolution
   2. Organisms with different embryonic origin modified to perform same functions because of occupying same ecological niche.
   3.                  
      1. Analogous structures
      2. Homologous structures
   4. Divergent evolution
   5.                  
      1. Q- Insecta
         R- Aves
         S- Mammalia
         N/B: First letter should be capital, reject small letter.
      2. Body covered with fur. Reject hair
         Presence of external ear/ pinna.
   6.                  
      1. B- Flesh R- Nectar
      2. Short, strong and curved.

CONFIDENTIAL

REQUIREMENTS

1. Specimen D- Raw banana (one piece per student )
2. 2 petri dishes.
3. A scapel/ a sharp razor blade.
4. Solution A (Distilled water).
5. Solution B (Salt solution).
6. A stop watch/ wall clock.
7. 2 labels.
8. 15cm ruler