Biology Paper 3 Questions and Answers - Londiani Joint Mock Exams 2022

QUESTIONS

1. You are provided with photograph L, K and J. Examine them.
   
   
   1. Using observable features only, state class of animals shown in the photograph L and K. (4 marks)
      L
      Class ………………………………………………………………………………………
      Reason………………………………………………………………………………
      K
      Class ………………………………………………………………………………………
      Reasons……………………………………………………………………………
   2.      
      1. On the photograph J name the parts labeled E, F and G. (3 marks)
      2. State the two adaptations of the structures labeled H in photograph J. (4marks)
   3.    
      1. The actual length of animal J in cm is shown by a section of the ruler in the photograph.
         Calculate the tail power (show your working) (2marks)
      2. State the significance of tail power to the life of fish in water. (1mark)
2. You are provided with the following;
   
   1. Hydrogen peroxide
   2. Specimen K
   3. Pestle and mortar
   4. 4 test tubes
   5. A scalpel
   6. Source of heat
   7. Test tube holder
      Using a scalpel, obtain three peeled cubed from specimen K measuring about 1cm x 1cm x 1cm. For the first cube, you are required to boil it in water for five minutes. For the second cube, you are required to crush it into a paste. For the last cube, you are required to use it as it is.
      Label three test tubes A, B and C and put 2ml of hydrogen peroxide in each test tube. To test tube A, add the boiled cube and record your observation.
      To test tube B. add the crushed paste and record your observation.
      To test tube C, add the unboiled cube remaining and record your observation.
      1. Complete the table below (3mks)
         

         Test tube	Observation
         A B C

      2. Explain your observation in test tube A (3mk)
      3. Between test tubes B and C, in which test tube was the volume of foam produced the highest? Explain (4mks)
      4. Apart from temperature, state three other factors that affect the rate of enzyme controlled reactions (3mks)
3. You are provided with a specimen labeled T which is a fruit. Use it to answer the questions that follow.
   
   1. Make a transverse section of the specimen T. Draw and label at least 3 parts. 6mks
   2. With reasons, state the identity of fruit T.
      Type of fruit…………………………………………..1mk
      Reason ………………………………………1mk
   3. Suggest the possible agent of dispersal and give two reasons
      Agent ……………………………………………………1mk
      Reason………………………………………………………
      2mk
   4. What is the placentation of T? …………………………………………………….1mk
   5. Specimen T was green in colour before it was treated with a plant hormone.
      Suggest the plant hormone.

CONFIDENTIAL
Each candidate shall require the following

1. 10ml hydrogen peroxide solution
2. Specimen K (Irish potato)
3. Mortar and a pestle
4. Four test tubes
5. Distilled water in a wash bottle
6. A scalpel
7. Means of heating (source of heat)
8. Test tube holder
9. One ripe banana fruit

MARKING SCHEME

1. Question 1
   
   1.      
      1. L – mammalia
         Body is covered with fur
         K – Aves
         Has a beak
         Body covered with feathers
         E- dorsal fin
         F – Operculum
         G – Pectoral fin
      2. Overlaps facing backwards to reduce friction for the fish as it moves in water
         Covered with mucus to reduce friction for the fish as it moves in water
   2.    
      1. TP =    length of the tail   x 100
                  total length of fish
         ^4.1/_9.3 x 100 = 44.09 %
      2. Allow for forward propulsion of fish in water.
2.    
   1. 
      

      Test tube	Observation
      A	No effervescence/no bubble production /No foam production
      B	High effervescence rate/high rate of bubble formation
      C	Little effervescence/ bubble formation/little foam formation.

      Reject no reaction
   2. No effervescence /bubble formation/form formation because boiling denatured the enzymes (catalase enzyme) hence hydrogen peroxides, was not broken down into water, and oxygen gas.
   3. Test tube B, because crushing of the cube increased the surface area for proper enzyme (catalase) action hence a high volume of hydrogen peroxide was broken down into water and oxygen compared to the cube in test tube c which has a small surface area expose to the hydrogen peroxide solution.
   4. PH, enzymes and substrate concentration contraction, enzyme inhibitors, co-enzymes and co-factors.
      Magnification between X1 and X5
3.    
   1. 
      
      Magnification between X1 and X5   
   2. Type of fruit Berry 1mk
      Reason has many seeds 1mk
   3. Agent Animal 1mk
      Reason brightly coloured; scented; fleshy; large; first 2mk
   4. Axile; 1mk
      Ethylene/ ethyne; 1mk