Biology Paper 3 Marking Scheme
KCSE CLUSTER TESTS 15
Biology Paper 3
15 marks
(a). X -Filament√ Rej. Wrong spelling
Function – Attachment of/expose anthers.√
Y – Sepals/calyx√
Function – Protect the flower parts during bloom/during bud development.√
(b). Gamepetalous/fused petal partially√
(c) Sepals are free/ polysepalous.√
(d). Hypogynous ovary/superior ovary.√
(e). (i) -Monocotyledonae√
(ii) -Stamens/anther/filaments are three √
-Petals/sepals are six/multiple of three√
10 marks
(b). No fizzing/no air bubbles form/no effervescence√ 1 mark
(c). Tube B :– Fast reaction√ due to favourable PH for the enzyme catalase reaction/ fizzing/air bubbles produced due to escaping oxygen gas.
Tube D: -No reaction √/fizzing since the enzyme catalase present in specimen P1 has been denatured√ by boiling.
(d). Tube A :– Very slow reaction because of a acidic PH that was unfavorable for the enzyme catalase to react.√1
Tube C: -Very slow reaction because NaOH created an alkaline PH that was unfavourable for the enzyme reaction.√
(e). (i).The rate of reaction will be rapid /will increase /there will be more fizzing.√1
(ii). Grinding releases more catalase√1 enzyme from P1 hence increase in the rate of reaction./Grinding increases√ the surface area over which the enzyme reacts.
(f). Netral /PH-7√
(g). (i). Hydrogen peroxide
(ii).Detoxification√ of hydrogen peroxide.
17 marks