Biology Paper 3 Questions and Answers with Confidential - Form 4 Mid Term 2 Exams 2021

BIOLOGY
PAPER 3
FORM 4 MID TERM 2

INSTRUCTIONS

• Answer all the questions in section A in the spaces provided.
• You are required to spend the first 15 minutes of the 1³/₄Hrs around for this paper readingthe whole paper carefully before commencing your work

1. You are provided with a specimen labelled Q and hydrogen peroxide.
   1. What part of the plant is specimen Q? (1mk)
   2. Cut two equal cubes whose sides are about 1cm from specimen Q. place one of the cubes into a boiling tube labelled A. Crush the other cube using pestle and mortar. Place the crushed material in another boiling tube labelled B. To each boiling tube add 4ml of hydrogen peroxide.
      1. Record your observations (2mks)
         Test tube A:...............................................................................
         Test tube B:...............................................................................
      2. Account for the results in b)(i) above (2mks)
      3. Write an equation for the break down of hydrogen peroxide (1mk)
   3. Peel half of specimen Q and crush in a mortar. Use the reagent provided to test for the various food substances in the extract obtained from the crushed material. Record the procedure, observation and conclusion in the table below (9mks)
      

      Food Substance	Procedure	Observation	Conclusion

2. The photograph below represents the lower and upper jaw of a mammal. Study it and answer the questions that follow.
   
   
   1. Name the parts labelled (5mks)
      A –
      B –
      C –
      D –
      F –
   2. Name one observable structural difference between B and C (1mk)
   3.        
      1. Draw and label the external structure of part labelled B (3mks)
   4.           
      1. Define the term “dental formula” (1mk)
      2. Write the dental formula from the diagram above (1mk)
   5. Suggest the mode of feeding in the above animal (1mk)
   6. Name one common disease that affect part labelled D (1mk)
   7. What class of food is digested in the cavity shown in the diagram? (1mk)
3. You are provided with the photographs below labelled A, B, C, D, E, F, G and a dichotomous key. Use them to answer questions that follow.
   
   1. Fill the missing information in the dichotomous key below (2mks)
      1.    
         1. Animals with jointed appendages ........................go to 3
         2. Animals without jointed appendages .....................go to 2
      2.     
         1. Animals with a slender long body ........................Nematoda
         2. Animals with a thick short body ..........................Mollusca
      3.      
         1. .................................................................go to 5
         2. Animals without wings ....................................go to 4
      4.     
         1. Animals with numerous legs ............................Myrioponda
         2. ...............................................................Hymenoptera
      5.      
         1. Animals with short antenna ..............................Diptera
         2. Animals with a pair of long antenna ....................go to 6
      6.     
         1. Animals with cuticulized fore wings ....................Dictyoptera
         2. Animals with a pair of membranous wings.............Hymenoptera
   2. Use the completed dichotomous key to identify the family to which each plant belongs (7mks)
      

      .	Identity	Steps followed
      A
      B
      C
      D
      E
      F
      G

   3. Name two features that are used to classify B as phylum arthropoda.(2mks)

CONFIDENTIAL

Requirements/ instruments:

1. A potato labelled Specimen Q: 1 per candidate
2. 10ml Hydrogen peroxide per candidate
3. Labels
4. 2 boiling tubes per candidate
5. Iodine solution
6. Benedict solution
7. Means of heating
8. 1% Copper (II) sulphate
9. 10% Sodium hydroxide solution
10. Test tube holder
11. 3 test tubes per candidate
12. Measuring cylinder
13. 2 droppers
14.  A Scapel
15. Pestle & mortar

MARKING SCHEME

1. You are provided with a specimen labelled Q and hydrogen peroxide.
   1. What part of the plant is specimen Q? (1mk)
      • Stem tuber
   2. Cut two equal cubes whose sides are about 1cm from specimen Q. place one of the cubes into a boiling tube labelled A. Crush the other cube using pestle and mortar. Place the crushed material in another boiling tube labelled B. To each boiling tube add 4ml of hydrogen peroxide.
      1. Record your observations (2mks)
         • Test tube A: Bubbling occurs but less than B
         • Test tube B: A lot of bubbling occurs
      2. Account for the results in b)(i) above (2mks)
         • A lot of bubbling in B because crushing increases the surface area for enzymatic activity
      3. Write an equation for the break down of hydrogen peroxide (1mk)
         • 2H₂O_2(aq) 2H₂O + O_2(g)
   3. Peel half of specimen Q and crush in a mortar. Use the reagent provided to test for the various food substances in the extract obtained from the crushed material. Record the procedure, observation and conclusion in the table below (9mks)
      

      Food Substance	Procedure	Observation	Conclusion
      Starch	Put 2cm3 of extract Q in a test tube. Add 2 – 3 drops of iodine solution	Colour changes to blue black	Starch present
      Protein	Put 2cm3 of extract Q in a test tube. Add 1cm3 of sodium hydroxide followed by a few drops of copper sulphate. Shake	No colour change	Protein absent
      Reducing sugar	Put 2cm3 of extract Q in a test tube. Add an equal amount of Benedict solution. Heat	Colour changes to yellow/orange/brown	Reducing sugars/simple sugars present

2. The photograph below represents the lower and upper jaw of a mammal. Study it and answer the questions that follow.
   1. Name the parts labelled (5mks)
      1. A –Upper canine
         B – Molar
         C – Premolar
         D – Gum
         F – Upper incisor
   2. Name one observable structural difference between B and C (1mk)
      1. B has a wider grinding surface than C
   3.         
      1. Draw and label the external structure of part labelled B (3mks)
   4.       
      1. Define the term “dental formula” (1mk)
         • A formula that shows the arrangement of different types of teeth and their numbers in half of the upper and lower jaws of an animal
      2. Write the dental formula from the diagram above (1mk)
         • I  2  C  1  PM  2  M  3 
              2      1        2       3
   5. Suggest the mode of feeding in the above animal (1mk)
      • Omnivorous
   6. Name one common disease that affect part labelled D (1mk)
      • Periodontal disease
   7. What class of food is digested in the cavity shown in the diagram? (1mk)
      • Starch
3. You are provided with the photographs below labelled A, B, C, D, E, F, G and a dichotomous key. Use them to answer questions that follow.
   1.  Fill the missing information in the dichotomous key below (2mks)
      1.      
         1. Animals with jointed appendages ........................go to 3
         2. Animals without jointed appendages .....................go to 2
      2.    
         1. Animals with a slender long body ........................Nematoda
         2. Animals with a thick short body ..........................Mollusca
      3.    
         1. Animals with wings ......................................go to 5
         2. Animals without wings ....................................go to 4
      4.     
         1. Animals with numerous legs ............................Myrioponda
         2. Animals with 3 pairs of legs ...........................Hymenoptera
      5.     
         1. Animals with short antenna ..............................Diptera
         2. Animals with a pair of long antenna ....................go to 6
      6.     
         1. Animals with cuticulized fore wings ....................Dictyoptera
         2. Animals with a pair of membranous wings.............Hymenoptera
   2. Use the completed dichotomous key to identify the family to which each plant belongs (7mks)
      

      .	Steps followed	identity
      A	1a, 3b, 4b	Hymenoptera
      B	1a, 3a, 5a	Diptera
      C	1a, 3a, 4a	Myrrapoda
      D	1a,3a,5b,6a	Dictyoptera
      E	1b, 2a	Nematoda
      F	1a,5b,6b	Hymenoptera
      G	1b,2b	Mollusca

   3. Name two features that are used to classify B as phylum arthropoda.(2mks)
      • Segmented body
      • Paired limbs