Biology Paper 3 Questions, Answers and Confidential - Bunamfan Post Mock 2021 Exams

Instructions to Candidates

• Answer ALL the questions in the spaces provided.

For Examiner's Use Only

QUESTIONS

1. You are provided with the following materials;
   Substance labelled L
   2cm³ Copper sulphate solution
   2cm³Sodium hydroxide solution
   2cm³ DCPIP solution
   2cm³ Benedict’s solution
   Source of heat
   3 test tubes
   3 droppers
   You are provided with a substance labeled L. Make a solution of substance L by adding 20 ml of distilled water and stir thoroughly. Design an experiment to investigate the food materials present in L. (9 marks)
   

   Substance	Chemical test	Procedure	Observations	Conclusion
   L
   L
   L

   1. State the importance of the food substances present in L to the human body. (2 marks)
      ……………………………………………………………………………………………………………………………………………………………………………………………………
   2. Describe how the body deals with the substances mentioned in (a) above when they are in excess. (2 marks)
      ……………………………………………………………………………………………………………………………………………………………………………………………………
2. Study the photographs below and answer the questions that follow.
   
   
   1.                  
      1. Identify the type of response exhibited by specimen A. (1 mark)
         …………………………………………………………………………………………………
      2. What is the survival value of the response you have identified in (a)(i) above. (1 mark)
         …………………………………………………………………………………………………
   2.                  
      1. Identify the phenomenon exhibited by specimen B. (1 mark)
         …………………………………………………………………………………………………
      2. State the significance of the phenomenon in (b) (i) above. (1 mark)
         …………………………………………………………………………………………………
   3. Explain how the response exhibited by seedlings in photograph C occurred. (3 marks)
      ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
   4. Study the photograph below showing a certain trait in man.
      
      
      1. Identify the trait exhibited in the photograph above. (1 mark)
         …………………………………………………………………………………………
      2. The trait you have identified in (d)(i) above is sex linked. In which chromosome is it contained. (1 mark)
         …………………………………………………………………………………………
      3. Name any other sex linked trait in man. (1 mark)
         …………………………………………………………………………………………
      4. The man in the photograph married a woman. Use a genetic cross to predict the offspring of the above marriage. Let YH represent the gene for the trait above. (4 marks)
   5. The photographs below show certain chromosomal mutations.
      
      
      1. Identify them
         P ………………………………………………………………………… (1 mark)
         Q ………………………………………………………………………… (1 mark)
3. Study the photographs below and answer the questions that follow.
   
   
   1. Give two visible survival adaptive features for the organism in photograph X. (2 marks)
      ……………………………………………………………………………………………………………………………………………………………………………………………………
   2. Identify the dentitions exhibited in photograph Y and Z (2 marks)
      Y ……………………………………………………………………………………………
      Z ……………………………………………………………………………………………
   3. Study the photographs below showing a certain type of tooth and teeth arrangement in man.
      
      
      1. Label any three parts of the tooth in photograph S. (3 marks)
      2. Give two adaptations of the tooth to its function. (2 marks)
         ……………………………………………………………………………………………………………………………………………………………………………………………………
      3. Write the dental formula for the teeth arrangement in photograph T. (1 mark)

MARKING SCHEME

1. You are provided with the following materials;
   Substance labelled L
   2cm³ Copper sulphate solution
   2cm³Sodium hydroxide solution
   2cm³ DCPIP solution
   2cm³ Benedict’s solution
   Source of heat
   3 test tubes
   3 droppers
   You are provided with a substance labeled L. Make a solution of substance L by adding 20 ml of distilled water and stir thoroughly. Design an experiment to investigate the food materials present in L (9mks)
   

   Substance	Chemical test	Procedure	Observations	Conclusion
   L	DCPIP Reject Vitamin C plus subsequent steps	Put 1cm3 of DCPIP into a test tube. Add solution L dropwise;	Colour of DCPIP disappears/purple; Reject DCPIP decolourised	DCPIP present;
   L	Benedict’s Reject Reducing sugars plus subsequent	Put 1cm3 of solution L into a test tube Add 1cm3 of Benedict’s solution Boil ;	Green ;	Traces /little reducing sugars present; Reject Reducing sugars alone
   L	Biuret’s Reject Proteins plus subsequent	Put 1cm3 of solution L into a test tube Add 1cm3 of Sodium Hydroxide  solution Add 1cm3 of Copper Sulphate solution;	(Light) purple;	Proteins present;

   1. State the importance of the food substances present in L to the human body. (2mks)
      • Proteins –used in formation of body tissues/enzymes/hormones
      • Glucose –oxidised by cells to release energy
      • Vitamin C-protection against diseases mark any 2
   2. Describe how the body deals with the substances mentioned in (a) above when they are in excess. (2mks)
      • Proteins –excess amino acids deaminated
      • Glucose –converted to glycogen and stored in liver cells
      • Vitamin C-excreted (as oxalates) mark any 2
2. Study the photographs below and answer the questions that follow.
   
   
   1.                        
      1. Identify the type of response exhibited by specimen A (1mk)
         • Haptonasty
      2. What is the survival value of the response you have identified in (a)(i) above (1mk)
         • A way of obtaining some limited mineral nutrients
   2.                  
      1. Identify the phenomenon exhibited by specimen B (1mk)
         • Etiolation
      2. State the significance of the phenomenon in (b) (i) above (1mk)
         • To reach/search/seek/obtain light
   3. Explain how the response exhibited by seedlings in photograph C occurred (3mks)
      • Seedlings subjected to unilateral/ unidirectional source of light ;causing auxins to migrate / diffuse to the dark side of the shoot;/ high concentration of auxins on dark side causing faster growth; on that side than the lit side/ faster cell elongation/ faster cell enlargement/ faster cell growth on the side than the lit.
   4. Study the photograph below showing a certain trait in man.
      
      
      1. Identify the trait exhibited in the photograph above (1mk)
         • Hairy pinna
      2. The trait you have identified in (d)(i) above is sex linked. In which chromosome is it contained (1mk)
         • Y
      3. Name any other sex linked trait in man (1mk)
         • Premature baldness
         • Colourblindness
         • Haemophilia
      4. The man in the photograph married a woman. Use a genetic cross to predict the offspring of the above marriage. Let Y^H represent the gene for the trait above. (4mks)
   5. The photographs below show certain chromosomal mutations.
      
      
      1. Identify them
         • P Duplication
         • Q Deletion
3. Study the photographs below and answer the questions that follow.
   
   
   1. Give two visible survival adaptive features for the organism in photograph X (2mks)
      • Presence of ( large/long/curved) sharp/sharp pointed canine for piercing ;
      • Camouflage/blend well with environment concealing/hiding themselves from their predators/prey ;
      • Presence of fur to insulate against the low temperature
   2. Identify the dentitions exhibited in photograph Y and Z (2mks)
      • Y Heterodont
      • Z Homodont
   3. Study the photographs below showing a certain type of tooth and teeth arrangement in man.
      
      
      1. Label any three parts of the tooth in photograph S (3mks)
      2. Give two observable adaptations of the tooth to its function (2mks)
         • Broad surface to increase surface area for chewing
         • Cusps /ridges to increase surface area for chewing
      3. Write the dental formula for the teeth arrangement in photograph T (1mk)
         
         Reject
         • If Commas and capital letters are used in the dental formula
         • If Divisional line is missing in the dental formula

CONFIDENTIAL

REQUIREMENTS
Each candidate will require the following:

• One spatula of substance labelled L (Fortified Exe wheat flour)
• 2cm³ Copper sulphate solution
• 2cm³Sodium hydroxide solution
• 2cm³ DCPIP solution
• 2cm³ Benedict’s solution
• Source of heat
• 3 test tubes
• 3 droppers
• 2oml of distilled water in a beaker