Biology Paper 3 Questions and Answers - Maranda High School Mock Exams 2023

Instructions to Candidates

• Answer ALL the questions in the spaces.
• All working MUST be clearly shown where necessary.

1. You are provided with a specimen R and the following reagents.
   • Dilute HCL                       10ml of measuring cylinder
   • Dilute Hydrogen               Peroxide Scalpel
   • Dilute Sodium                  Hydroxide 3 labels
   • Three test tubes               Iodine solution
     Using the above provisions, conduct the procedure below.
     1. Label the test tubes A, B, and C.
     2. Using a scapel obtain three cubes of side 1 cm from specimen R and reserve the rest.
     3. Using a scalpel, chop the first and the second cubes into tiny pieces separately and place into the test tubes A and B respectively.
     4. Place the remaining cube into test tube C as a whole.
     5. Add 2cm³ of the dilute HCL into the test tube A, then 2cm3 of dilute Sodium Hydroxide into each of the the test tubes B and C.
     6. Add about 5cm³ of Hydrogen Peroxide into each of the three test tubes A, B and C.
        1. Observe the amount of effervescence produced in each test tubes and complete the table below. (6 marks)  
           

           Test Tube	Contents	Amount of effervescence observed
           A
           B
           C

        2. Explain the observation made in test tube A and B. (3 marks)
        3. What would be the expected result if K was first boiled before conducting the above procedures. Explain. (2 marks)
        4. Use the reagents provided to test for the food substance present in specimen K reserved from
           Observe and record in the table below. (3 marks)
           

           Procedure	Observation	Conclusion

2. The photographs below are of certain plant organs. Use them to answer the questions that follow.
   
   1.  
      1. Identify the structures A and B in Photograph Q. (2 marks)
      2. Give the role of structure C (1 mark)
      3. Using observable features only, state the agent of pollination for specimen Q giving a reason for your answer. (2 marks)
         Agent: ……………………………………………………………………………………………….
         Reason: ……………………………………………………………………………………………...
   2. Specimen in photograph R was cut longitudinally and displayed as shown, use it together with photograph T to answer the questions that follow
      1. Give the functional difference between R₆ and T₅. (1 mark)
      2. State the type of placentation in the two specimens in photographs R and T giving a reason in each case. (4 marks)
      3. Giving two observable features, state the mode of dispersal of specimen R. (3 marks)
      4. Identify one cause for seed dormancy displayed in R and state one way of breaking it.    (2 marks)
3. The following are photographs of bones of the mammalian skeleton. Use them to answer the questions that follow.
   
   1. Giving the main distinguishing feature in each case, identify the bones P1 and P2. (4 marks)
   2. State two functions of the structure X. (2 marks)
   3. Photograph P3 is a composite set of two bones.
      1. Give the identity of the parts labelled M and N. (2 marks)
      2. Name the borne that articulates with P3 at its proximal end and state how the named is adapted to its function. (2 marks)
      3. Other than muscle attachment, give the other function of the part labelled J. (1mark)
      4. Give one nutritional value of the human endoskeleton. (1 mark)

CONFIDENTIAL

Provide each candidate with the following;

• One medium sized irish potato-specimen R
• 18cm³ dilute hydrogen peroxide
• 6cm³ dilute sodium hydroxide
• 3cm³ dilute hydrochlorid acid
• 2cm³ Iodine Solution
• Scapel
• 3 labels
• 3 clean test tubes on a test Tube rack
• 1 dropper
• 10ml measuring cylinder

MARKING SCHEME

1.  
   1.   
      

      Test Tube	Contents	Amount of effervescence observed
      A	Chopped pieces of R                  +          dilute HCL                  +    dil. hydrogen peroxide;	No / little/ small amount of (effervescence/foam/froathing)  Acc. Slow effervescence/ gas production Rj: If specific gas is mentioned
      B	Chopped pieces of R                +   dil. Sodium mhydroxide                +  dil Hydrogen peroxide;	Vigorous? Rapid/ Fast/ a lot of effervescence/   Large amount/ more gas production.
      C	Whole cube of R/ unchopped R                        +        dil Sodium hydroxide                        +      dil. Hydrogen peroxide	Moderate/ Medium/ Average (effervescence) gas production;  Acc: less than B more than A

   2.  
      • A: Acidic medium/ Low pH did not favour the working of the enzyme (catalase) / destroyed/ denatured the enzyme (catalase) Thus no reaction/action.
      • B: Alkaline medium pH/ NaOH favoured the action of enzyme (catalase); chopping R provided/ increased surafce area for enzyme  action; (hence the rapid reaction)
   3.  
      • No effervescence/ No bubble/ gas production/ No reaction;
      • Explanation: Boiling denatured the enzyme (catalase) hence no reaction;
   4.  
      

      Procedure	Observation	Conclusion
      Adds dropwise 3 drops of Iodine solution to Specimen R;   Rj: Qunatified vol of Iodine soln.	Blue-black/ blueblack colour change Rj :Black alone       Blue alone       Blackish/ Bluish       Blue black	Starch  present;

2.  
   1.  
      1.  
         • A: Staminal tube
         • B: Filament;
      2. Protects the flower at the budding stage;
      3. Agent: Insect;
         Reason: Brightly coloured petals/corolla to attract insects.
   2.  
      1.  
         • R6 - used for attachment of the fruit to the stalk/ stem while
         • T5 - is used for attachment of the seed/ ovule to the placenta;
      2.  
         • R: Basal placentation
           Reason: PLacenta nappears at the abse of the ovary/ fruit.
         • T: Marginal placentation
           Reason: Present of placenta forms a single ridge alog the margin/ edge of the fruit wall/ pod.
      3. Mode: Animal
         Features: Brightly coloured epicarp/ mesocarp/ exocarp
         Fleshly mesocar
      4.  
         • (Hard) impermeable endocarp/ testa / seed coat;
         • Scarification; OWTTE
         • Cracking
         • Passing through the gut of herbivores
3.  
   1.  
      • P1: (Typical) Cervical vertebra; Rj: plural vertebrae
        Feature;
        • Presence of vertebraterial canal
        • Branched transverse processes;
      • P2: ,Thoracic vertebra. Rj plural
        Feature; Presence of long neural spine
   2.  
      • Absorbs mechanical shock.
      • Reduces friction between vertebrae;
      • Form flex points along the vertebral column allowing for bending of the column/ Makes vertebral column flexible
   3.  
      1.  
         • M: Radius;/ ,shaft of radius
         • N: Ulna; / shaft of ulna
      2. Bone: Humerus; Rj wrong spelling
         Adaptation;
         • Long shaft to increase S.A for muscle ,attachment;
         • Tuberosities increase S.A for muscle attachment;
         • Round head to fit in the glenoid cavity of scapula to allow for rotational movemnt of the arm at the shoulder; Bicipital groove for passage of biceps muscles;
         • Trochlea to fit in the sigmoid notch to form hinge n/ elbow joint.
         • Olecranon fossa to articulate with olecranon process to prevent overstretching of the forearm.
      3. Prevents overstretching of the forearm at the elbow.
      4. Reservoir for calcium and phosphate ions.