Biology Paper 3 Questions And Answers with Confidentials - Form 3 Term 2 Opener Exams 2021

BIOLOGY
PAPER 3
TERM 2 OPENER EXAM

INSTRUCTIONS

• Write your name and index number in the spaces provided.
• You are required to spend the first 15 minutes of 13/4 hours allowed for this paper reading the whole paper carefully before commencing your work.
• Answers must be written in the spaces provided in the question paper.
• Additional pages should not be inserted candidates may be panelized for recording irrelevant information and for incorrect spellings especially of technical terms.

1. You are provided with liquids labelled Q1 and Q2. Spare about 10ml of the liquids for part (a) of this question. Using a piece of thread, tie tightly one end of the visking (dialysis) tubing. Open the other end of the tubing and half fill it with liquid Q1. Tightly tie this end. Ensure there is no leakage in both ends. Immerse the tubing in a beaker containing liquid Q2. Leave the set up for at least 30 minutes.
   1. Using iodine and Benedict’s solution provided; test for the food substance in liquids Q1 and Q2. Record the procedure, observation and conclusion in the table below.(6mks)
      

      LIQUID	PROCEDURE	OBSERVATION	CONCLUSION
      A
      B

      After at least 30 minutes remove the visking tubing from the beaker and wash the outside of the tubing thoroughly to remove traces of liquid Q2.
   2. Using the same reagents, test the food substance in liquid Q1 in the visking tubing.
      Record your observations and conclusion in the table below. (2mks)
      

      LIQUID	OBSERVATION	CONCLUSION
      Q1

   3.    
      1. Name the physiological process being demonstrated by this experiment. (1mk)
      2. Name two parts of the human body where the process named in (c) (i) above takes place. (2mks)
   4. Account for the results obtained after carrying a second food test on liquid Q1. (2 mks)
2. You are provided with diagrams of specimens taken from a mammal. Study them carefully and answer the questions that follow.
   
   1. Identify the diagrams labeled below. (3 marks)
      X
      Y
      Z
   2. State the diet of the animal from which diagram x was taken and give a reason for your answer. 
      1. Diet(1 marks)
      2. Reason (2 marks)
   3. Name the parts labeled (3 marks)
      A
      B
      D
   4. How are the following structures adapted to their functions (2 marks)
      D
      C
   5. State the function of the parts labeled. (2 marks)
   6. State one structural difference between Y and Z (1 mark)
3. Examine the seedling below and use them to answer the question that follow.
   1. Name the part labeled C,D, E and state their importance for the seedling.
      
      1. C:
         Importance (1mk)
      2. D.
         Importance (1mks)
      3. E
         Importance. (lmk)
   2. The R series of seedlings on the roots later in its life:
      1. What is the name of the swelling: (lmk)
      2. Name the organisms that would be found in the swellings (1mk)
      3. Explain the relationship that exists between the named organisms and the plant. (1mks)
   3.     
      1. State the types of germination exhibited by R series of the seedling
      2. Give a reason for your answer in (c) (i) above. (1mk)
   4. State any two external factors necessary for germination. (2mks)

Biology confidential
Each candidate will require the following:

• 50ml distilled water labelled Q1.
• One ripe tomato labelled specimen J.
• 2 pieces of sewing machine cotton thread 9 15cm long each)
• Benedict’s solution
• One mature pod from leguminous plant labelled specimen K.
• Iodine solution,
• One mature (dry) fruit of Bidenspilosa( Black jack)
• Labelled specimen L.
• 10cm long piece of visking tubing (wet) and preferably of 3cm width.
• 100 ml solution ( made of 2% starch and 20% glucose) labelled Q2.
• Means of heating /Flame ( candle or Bunsen burner)
• 100ml beaker
• A measuring cylinder – upto 10ml
• Distilled water.
• 6 test tubes
• Tap water / water in a wash bottle
• Test tube rank
• Test tube holder
• A sharp razor blade / scalped

‘Note’
Guide lines for the preparation of solution Q2

• To prepare 1 litre of solution Q2, dissolve 20g starch in about 500ml distilled water, dissolve 200g glucose in the solution.
• Make up the total volume of the mixture 1 litre by adding distilled water.

MARKING SCHEME

1.    
   1.     
      

      LIQUID	PROCEDURE	OBSERVATION	CONCLUSION
      Q1	Add iodine solution to solution Q1	No colour changes/iodine colour remained /brown colour is retained	No starch / starch absent;
      	Add equal amount of benedict’s Solution to Q1 and then heat.	No colour change / benedicts solution remained unchanged /Blue colour of benedicts solution remains	No reducing sugar/reducing sugar absent.;
      Q2	Add iodine solution to Q2	Black/blue/black/ Blakishblue/bluish/ black colour forms	Starch present
      	Add equal amounts of Benedict’s solution to Q2 then heat	Green yellow orange colours observed	Reducing sugars present

      (6mks)
   2.    
      

      LIQUID	OBSERVATION	CONCLUSION
      Q1	Iodine colour retained /brown colour of iodine retained / No colour change	No starch/starch absent
      	Green ➙ yellow ➙ orange; ( correct sequence)	Reducing sugar present

                                             ½ mk each                                               Total: 2 mks
   3.      
      1. Diffusion;
      2. Ileum / small intestine; placenta /lungs/ proximal convoluted tubule;
   4. The visking tubing is semi-permeable and has small pores; reducing sugar molecules are small and hence move from region of high concentration to region of low concentration into visking tubing; starch molecules are large and did not diffuse through the small pores of the visking tube;
2.      
   1.      
      • X- skull
      • Y- Canine
      • Z- pre-molar
   2.    
      1.  Carnivorous
      2. Long canines, specilaized molars/ carnasial teeth for ripping apart flesh
   3.     
      A - pulp cavity
      B -  dentine
      D -  crown
   4.        
      • D - Has cusps/ ridges; to enable it grind / chew food; (into smaller pieces)
      • C- The crown is specilaized and is more jagged to enable ripping and tearing of flesh and breaking of bones.
                 
3. 1.    
      • C -Hypocotyl
        Importance —protects the plumule /shoot tip/first foliage leaves /opens path through the soil for the cotyledon to pass/pulls the cotyledon out of the soil.
      • D Cotyledons/seed leaves
        Importance:
        • Photosynthesis
        • Food storage /food reserves
        • Provide food for germinating seedlings /young plants.
      • E Coleoptile/plumule sheath Rej: cover/coat
        Importance
        • protects the delicate tip/first leaves/foliage leaves
   2.           
      • nodules/root nodules
      • Rhizobium/Rhizobia/Rhizobium bacteria rej. Bacteria alone.
      • Symbiotic relatioship in which bacteria gets protection and nutrients while the plant gets nitrogen in form of nitrates fixed by bacteria.
   3.           
      • Epigeal
      • Cotyledons are brought out of the ground.
   4.          
      • Water
      • Oxygen;
      • Optimum temperature