Biology Paper 3 Questions, Answers and Confidential - Cekena Pre Mocks 2022

INSTRUCTIONS TO CANDIDATES

• Write your name, admission number, date, and signature and school name in the spaces provided
• Answer ALL the questions in the spaces provided in the question paper
• 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

For examiners use only

QUESTIONS

1. You are provided with Irish potato tuber; dilute Hydrogen peroxide solution, washing up solution, solutions labelled K, PH 4, solution labelled L of PH 7, and solution labelled M of PH 9 You are also provided with 10mI measuring cylinder, white tile, glass rod, scalpel, stop watch, test tubes in a test tube rack
   Peel the potato tuber and cut a piece measuring lcm³ Crush it on a white tile using the glass rod to obtain a paste Divide the paste into 3 portions and use them as follows
   1. Put 2cm³ of solution K into a 10ml measuring cylinder Add one portion of the potato paste into the cylinder containing solution K Read and record the volume of the mixture in the table below Add one drop of the washing up solution Add lcm³ of hydrogen peroxide solution into the mixture and immediately start a stop watch At the end of 2minutes read the mark to which the foam rises and record in the table below Clean and rinse the measuring cylinder with distilled water
   2. Put 2cm³ of solution L into a 10ml measuring cylinder Add the second portion of the potato paste into the cylinder containing solution L Read and record the volume of the mixture in the table below Add one drop of the washing up solution Add lcm³ of hydrogen peroxide solution into the mixture and immediately start a stop watch At the end of 2minutes read the mark to which the foam rises and record in the table below Clean and rinse the measuring cylinder with distilled water
   3. Put 2cm³ of solution M into a 10ml measuring cylinder Add the third portion of the potato paste into the cylinder containing solution M Read and record the volume of the mixture in the table below Add one drop of the washing up solution Add lcm³ of hydrogen peroxide solution into the mixture and immediately start a stop watch At the end of 2minutes read the mark to which the foam rises and record in the table below
      1. Complete the table below by calculating the volume of the foam produced in each of the solutions using the data obtained in (i), (ii) and (iii)(3mks)
         

         	SOLUTION K	SOLUTION L	SOLUTION M
         Volume of the solution + Potato portion
         Volume of the solution + potato portion + foam
         Volume of the foam

      2. Explain the observation made when hydrogen peroxide was added to the mixture (2mks)
      3. Account for the difference in the volume of the foam that was produced in solution K and solution M (2mks)
      4. Cut a piece of potato measuring lcm3 from the remaining potato Use the reagent provided to test for the food substance (3mks)
         

         Test	Procedure	Observation	Conclusion

2. You are provided with photographs of specimen Q and N together with actual specimens H, K and P specimen H is a complete plant while K is a portion of a different plant Observe the specimens and the photographs and use them to answer the questions that follows
   1. State two observable differences between the leaves of H and K (2mks)
   2. Explain how the stem of specimen H adapts the plants to photosynthesis (2mks)
   3. State the ecological importance of specimen H (1mk)
   4. Describe how specimen K is adapted to its habitat (2mks)
   5. Explain the consequences of spilling common salt to the soil in which specimen H is growing (2mks)
   6. With a reason identify the subdivision from which specimen H and K belong (2mks)
   7. Cut a longitudinal section of specimen P using the observable features
      1. Identify the type of placentation (1mk)
      2. With a reason classify the type of fruit to which it belongs (2mks)
   8. Use the photographs of Q and N to complete the table below (4 mks)
      
      

      SPECIMEN	MODE OF DISPERSAL	ADAPTIVE FEATURE
      Q
      N

3. Below is a photograph of a dissected rat with abdominal organs spread out Examine it
   
   
   1. State two characteristics that distinguish the dissected animal into its taxonomic class (2mks)
   2. Name the parts labelled (3mks)
      1. B
      2. C
      3. F
   3. State
      1. Two functions of part labelled A (2mks)
      2. The function of D (1 mk)
   4. Other than homeostasis and excretion state two functions of structure E (2mks)
   5. Given the magnification of the specimen in the photo as X 067, calculate the length of the rat from X to Y (2mks)

MARKING SCHEME

1. You are provided with Irish potato tuber; dilute Hydrogen peroxide solution, washing up solution, solutions labelled K, PH 4, solution labelled L of PH 7, and solution labelled M of PH 9. You are also provided with 10mI measuring cylinder, white tile, glass rod, scalpel, stop watch, test tubes in a test tube rack.
   Peel the potato tuber and cut a piece measuring lcm3. Crush it on a white tile using the glass rod to obtain a paste. Divide the paste into 3 portions and use them as follows.
   1. Put 2cm³ of solution K into a 10ml measuring cylinder. Add one portion of the potato paste into the cylinder containing solution K. Read and record the volume of the mixture in the table below. Add one drop of the washing up solution. Add lcm³ of hydrogen peroxide solution into the mixture and immediately start a stop watch. At the end of 2minutes read the mark to which the foam rises and record in the table below. Clean and rinse the measuring cylinder with distilled water.
   2. Put 2cm³ of solution L into a 10ml measuring cylinder. Add the second portion of the potato paste into the cylinder containing solution L. Read and record the volume of the mixture in the table below. Add one drop of the washing up solution. Add lcm³ of hydrogen peroxide solution into the mixture and immediately start a stop watch. At the end of 2minutes read the mark to which the foam rises and record in the table below. Clean and rinse the measuring cylinder with distilled water.
   3. Put 2cm³ of solution M into a 10ml measuring cylinder. Add the third portion of the potato paste into the cylinder containing solution M. Read and record the volume of the mixture in the table below. Add one drop of the washing up solution. Add lcm³ of hydrogen peroxide solution into the mixture and immediately start a stop watch. At the end of 2minutes read the mark to which the foam rises and record in the table below.

a) Complete the table below by calculating the volume of the foam produced in each of the solutions using the data obtained in (i), (ii) and (iii)(3mks)

b) Explain the observation made when hydrogen peroxide was added to the mixture (2mks)

• There is foaming/ bubbling; enzyme catalase present in the potato break down hydrogen peroxide into water and oxygen
• Acc word/chemical equation for explanation
• Rej wrong spelling for catalase

c) Account for the difference in the volume of the foam that was produced in solution K and solution M (2mks)

• More foam is produced in M; it is optimum pH for enzyme catalase.

d) Cut a piece of potato measuring lcm³ from the remaining potato .Use the reagent provided to test for the food substance (3mks)

Rej blue/ black

2. You are provided with photographs of specimen Q and N together with actual specimens H, K and P. specimen H is a complete plant while K is a portion of a different plant. Observe the specimens and the photographs and use them to answer the questions that follow.
a) State two observable differences between the leaves of H and K.  (2mks)

 Reject blue/black
b) Explain how the stem of specimen H adapts the plants to photosynthesis (2mks)

• Firm/ upright to expose the leaves to light for photosynthesis
• Green to trap sunlight for photosynthesis

c) State the ecological importance of specimen H  (1mk)

• Producer/ food for herbivores
• Habitat for small animals
• Reduce CO₂ in the atmosphere
• Ground cover

d) Describe how specimen K is adapted to its habitat (2mks)

• Woody for support
• Has thorns on the stem for protection against herbivores

Rej predators

e) Explain the consequences of adding concentrated salt solution to the soil in which specimen H is growing. (2mks)

• The common salt will make the surrounding soil solution hypertonic to cell sap; the plant lose water to soil by osmosis hence become dehydrated/ wilt/dry/die.

f) With reasons identify the subdivisions from which specimen H and K belong (2mks)

• Angiospermaphyta: - veined leaves

Seed bearing / flower bearing
Rej parallel veined, net veined

g) Cut a longitudinal section of specimen P using the observable features.
Identify the type of placentation  (1mk)

• Basal

With a reason classify the type of fruit to which it belongs. (2mks)

• Drupe ; - one seeded

h) Use the photographs of Q and N to complete the table below (4 mks)
DIAGRAM

3. Below is a photograph of a dissected rat with abdominal organs spread out. Examine it
a) State two characteristics that distinguish the dissected animal into its taxonomic class.(2mks)

• Possess hair on their body/ body covered with hair
• Presence of muscular diaphragm
• Presence of external ears/ pinna

b) Name the parts labelled   (3mks)

1. B - caecum
2. C – small intestines
3.  F - duodenum

c) State

1. Two functions of part labelled A  (2mks)
   • Temporary storage of food during digestion
   • Churning
   • digestion
2. The function of D
   • Harbours bacteria that digest cellulose owtte

d) Other than homeostasis and excretion slate two functions of structure E (2mks)

• Red blood cell formation
• Synthesis of plasma proteins
• Production of bile

e) Given the magnification of the specimen in the photo as X 0.67, calculate the length of the rat from X to Y (2mks)

• actual length = (use students value of x y and follow through)

CONFIDENTIAL

INSTRUCTIONS

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

Each candidate requires the following

• Specimen H (Lantana twig with flowers/fruits)
• Irish potato
• Specimen K (creeping grass complete with roots and internodes)
• Specimen P (medium sized Avocado fruit)
• 5mls of Dilute Hydrogen peroxide solution
• 5mls of Solution K (0.5 M Hydrochloric acid)
• 5mls of Solution L (Distilled water)
• 5mls of Solution M (0.5 M sodium hydroxide solution)
• Access to Washing up solution (Glycerine)
• Stop watch
• Measuring cylinder
• Dropper
• Glass rod
• White tile
• Scapel
• 4 test tubes in a test tube rack
• Iodine solution
• Distilled water in a wash bottle
• Each student should carry a clear ruler