Biology Paper 3 Questions and Answers with Confidential - Cekana Mock Exams 2023

INSTRUCTIONS 

• You are not allowed to start working with the apparatus for the first 15 minutes of the 1 & ¾ hours allowed for this paper. This time is to enable you to read the question paper and make sure you have all the chemicals and apparatus that you may need.

QUESTIONS

1. You are provided with three solutions K, M3 & M4. M3 is the same as M4 except that M4 is boiled. You are also provided with 2 visking tubing, piece of thread, two beakers, 6 test tubes in a rack, thermometer, test tube holder and the following solutions; iodine, sodium hydroxide, copper(II) sulphate and Benedict’s.
   1. Tie one end of the visking tubing tightly using a thread. Put 10ml of solution K and 1 ml of solution M3 into the visking tubing. Tie the other end of the visking tubing. Place the visking tubing in a beaker half filled with iodine solution. Take a second visking tubing and repeat the same using M4. Place the beakers containing the visking tubing in a water bath maintained between (35 – 38)°C. Allow the set-ups to stand for 30minutes. Then after 30 minutes remove the visking tubings and test their contents and those of the beakers.
      

       

      SAMPLE 1 (K + M3)            (6 MARKS)

      CONTENTS IN	TEST	OBSERVATION	CONCLUSION
      VISKING                                                       TUBING	Iodine test
      	Benedict’s test
      	Biuret’s test
      BEAKER	Iodine test
      	Benedict’s test
      	Biuret’s test

      SAMPLE 2 (K + M4)            (6MARKS)

      CONTENTS IN	TEST	OBSERVATION	CONCLUSION
      VISKING                                                       TUBING	Iodine test
      	Benedict’s test
      	Biuret’s test
      BEAKER	Iodine test
      	Benedict’s test
      	Biuret’s test

   2. Account for the results in:
      1. Table 1 (1mark)
      2. Table 2 (2marks)
2. You have been provided with specimen labelled X. The specimen and the photograph of Y are obtained from the same animal. Use them to answer the question that follow.
   
   
   1. Giving two reasons identify Y.
      1. Identity (1mark)
      2. Reasons (2marks)
   2. Give two adaptations of the specimen labelled X (2marks)
   3. State two observable differences between X and Y (2marks)
   4. Make a drawing showing the anterior view of X and label all the parts (4marks)
   5. The photograph below shows bones from another animal
      
      
      1. Which part of the body was H obtained from (1mark)
      2. Identify G2 (1mark)
      3. With a reason name the type of joint at the proximal end of specimen H (2marks)
3. Study the photographs below and answer the questions that follow
   
   
   1. Name the type of relationship in:
      1. Photograph W (1mark)
      2. Photograph M (1mark)
   2. Explain your answer in a(ii) above (2marks)
   3. What is the importance of the relationship taking place in the photograph W (1mark)
   4. Using observable feature only explain two ways in which the flower is adapted for the activity taking place in photograph M (2marks)
   5.  
      1. Give the biological term used to refer to the phenomenon captured in photograph W between organisms A and B towards C (1mark)
      2. State two implications of the phenomenon mentioned in d(i) above (2marks)

CONFIDENTIAL

These instructions are to enable the head of institution and the teacher in charge of biology to make adequate preparations for 231/3 Biology Practical
No one else should have access to this information either directly or indirectly.

Each candidate requires the following

• 30 ml of solution K (mixture of starch and albumin)
• 3 ml of solution M3 (enzyme diastase)
• 3 ml of solution M4 (boiled enzyme diastase)
• Iodine solution (100ml)
• 6 test tubes in a test tube rack
• Specimen X (Thoracic vertebrae)
•  Test tube holder
• Means of timing
• Thermometer
• Water bath ( to hold two 100ml beakers simultaneously)
• Two visking tubings (each 6cm long) and threads to tie their ends
• Two 100 ml beakers

Access to

• Means of heating
• Sodium hydroxide solution (10%)
• Copper (II) sulphate solution (1%)
•  Iodine solution
•  Benedict’s solution

MARKING SCHEME

1.  
   1.  
      

      SAMPLE 1 (K + M3)            (6 MARKS)

      CONTENTS IN	TEST	OBSERVATION	CONCLUSION
      VISKING                                                       TUBING	Iodine test	Brown colour of iodine solution remained Rej. Solution remained brown	Starch absent
      	Benedict’s test	Blue colour of benedict’s solution changed to orange/brown Rej Soln changed to orange/brown	Reducing sugars present
      	Biuret’s test	Blue colour of copper (II) sulphate solution changes to violet/purple	Protein present
      BEAKER	Iodine test	Brown colour of iodine solution remained Rej. Solution remained brown	Starch absent
      	Benedict’s test	Blue colour of benedict’s solution changed to orange/brown	Reducing sugar present
      	Biuret’s test	Blue colour of copper (II) sulphate solution remained	Protein absent

       

      SAMPLE 2 (K + M4)            (6MARKS)

      CONTENTS IN	TEST	OBSERVATION	CONCLUSION
      VISKING                                                     TUBING	Iodine test	Iodine solution changed to blue black colour Rej soln changed to blue black	Starch present
      	Benedict’s test	Blue colour of benedict’s solution remained	Reducing sugar absent
      	Biuret’s test	Copper (II) sulphate solution changes to purple/violet colour	Protein present
      BEAKER	Iodine test	Brown colour of iodine solution remained	Starch absent
      	Benedict’s test	Blue colour of benedict’s solution remained	Reducing sugar absent
      	Biuret’s test	Blue colour of copper(II) sulphate solution remained	Protein absent

   2. Account for the results in:
      1. Table 1 (1mark)
         The semi-permeable visking tubing allows small sugar molecules to pass through but not the large starch and protein molecules
      2. Table 2 (2marks)
         Boiling denatured the enzyme; (amylase/diastase) hence no hydrolysis of starch occurred
2. You have been provided with specimen labelled X. the specimen and the photograph of Y are obtained from the same animal. Use them to answer the question that follow.
   
   
   1. Giving two reasons identify Y.
      1. Identity (1mark)
         Lumbar vertebrae
      2. Reasons (2marks)
         • Short and broad neural spine
         • Long and prominent traverse process
         • Large and broad centrum
         • Has prezygapophysis and postzygapophysis Mark first 2
   2. Give two adaptations of the specimen labelled X (2marks)
      • Long and broad neural spine to provide large surface area for attachment of muscles
      • Has neural arch and centrum which support and protect the spinal cord
      • Has centrum with demifacets i.e. capitulum facets to articulate with capitulum of the rib
      • Has traverse process with tuberculum facets for articulation with articulum of the limb
   3. State two differences between X and Y (2marks)
      

      Bone X	Bone Y
      Long neural spine	Has broader but shorter neural spine
      Short traverse process	Long well developed traverse process
      Has demifacets for articulation with ribs	Lacks facets for articulation to ribs
      Lacks prezygapophysis and postzygapophysis	Has prominent prezygapophysis and postzygapophysis

   4. Make a drawing showing the anterior view of X and label all the parts (4marks)
      
      
      • D1 (continuous outline, no shading and tied to anterior view)
      • L3 (any 7 or 8 correct labels – 3marks; any 5 -6 labels – 2marks; any 3 – 5 labels – 1mark; below 3 award 0)
   5. The photograph below shows bones from another animal
      
      
      1. Which part of the body was H obtained from (1mark)
         Upper arm/upper forelimb
      2. Identify G2 (1mark)
         Sigmoid notch
      3. With a reason name the type of joint at the proximal end of specimen H (2marks)
         Ball and socket – the head is shaped like a ball to allow movement in more than one plane
3. Study the photographs below and answer the questions that follow
   
   
   1. Name the type of relationship in:
      1. Photograph W (1mark)
         Predation
      2. Photograph M (1mark)
         Symbiosis
   2. Explain your answer in a(ii) above (2marks)
      Bee benefits by obtaining nectar; from the flower while the flower benefits by getting pollinated
   3. What is the importance of the relationship taking place in the photograph W (1mark)
      To maintain the population of the prey and predator at carrying capacity of the habitat
   4. Using observable feature only explain two ways in which the flower is adapted for the activity taking place in photograph M (2marks)
      • Flower is funnel shaped/conical shaped to provide a landing platform for the bee
      • Brightly coloured/conspicuous to attract the bee
      • Rej. Nectaries, scented, stigma, pollen grains, filaments (not observable in the photo)
   5.  
      1. Give the biological term used to refer to the phenomenon captured in photograph W between organisms A and B towards C (1mark)
         Interspecific competition
      2. State two implication of the phenomenon mentioned in d(i) above (2marks)
         • Species which is better adapted survives while the less adapted may become extinct
         • Migration of the less adapted species to other areas/ habitat