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BIOLOGY FORM THREE

Marking scheme

Question 1

(a)  Omnivorous;                                                                                                               (1mk)

(b)  I – Molar;                                                                                                                    (1mk)

      II – Canine;                                                                                                                 (1mk)

(c)  H – Enamel / crown;                                                                                                  (1mk)

      J – Neck;                                                                                                                     (1mk)

(d)  Teeth II has flat top / ridged while tooth IV has chisel shaped top.                          (1mk)

(e)  Cutting / biting                                                                                                           (1mk)

(f)              i2         c3        pm2     m3    x 2          =          32                                            (1mk)

 2           3             2        3

     (g)  Used more for chewing / has greater contact with food particles; // is flat broad ridged / cusped holds food remains;

Question 2

(a)  (i) 

(ii)  mg =         Drawing length           =          20mm

                        Objects length                         10mm

            =          x 2;

  • (i)     Plantae;
    • Bryophyta;
    • Presence of;

Rhizoids;

Male and female branches

  • –  Leaves – photosynthesis
    • Capsule – spore producing
    • Rhizoids – anchorage, absorption of water and mineral salts.
    • Green contains chlorophyll for photosynthesis;
  • Sporulation
  • Green hence carry out photosynthesis / autotrophic

Question 3

Test – tubeOBSERVATIONSCONCLUSION
ABlue black/blue /black/bluish black;Starch present;
BBlue black/blue /black/bluish black;Starch present;
CBlue black/blue /black/bluish black;Starch present;

                                                                                                                              6/2 = 3 marks

(b)

Test – tubeOBSERVATIONSCONCLUSION
ABlue black/blue /black/ dark blue / bluish black;Starch present;
BNo colour change /brown/yellow colour / colour of iodine;Starch present;
CBlue black/blue /black/bluish black;Starch present;

                                                                                                                                          6 marks

(c)  Control experiment

(d) (i)   Distase / enzyme /starch digesting enzyme/ ptyalin / saliva enzyme /salivary enzyme; (1mark)

      (ii)  Because it is converted / digested / changed starch / can be denatured by boiling / acts within a range of temperature between 35 0C – 380C / optimum temperature; only 1 (1 mark)

(e)  Mouth / duodenum / ileum;

      NB (f) tied to table (b)

  • B – Starch absent / No colour change /colour of iodine remains because starch has been digested / converted / hydrolysed / broken down into glucose / maltose / simple sugar; (1mark)

      C – Starch present because boiling denatured enzyme /L2 ; thus starch not broken down / not digested / not acted upon;