KCSE Secondary Level Marking Scheme Biology Paper 2 (Practical)  Question Paper

Exam Name: Marking Scheme Biology Paper 2 (Practical) 

Course: Secondary Level

Institution/Board: KCSE

Exam Year:2005

MARKING SCHEME BIOLOGY PAPER 2 (PRACTICAL)
KCSE 2005
Each candidate will require the following
A shoot of maize plant with some leaves labeled specimen X
A leafy shoot of Bidens pilosa labeled specimen Y
Iodine solution
Benedict’s solution
Means of heating / water bath
Means of cutting / scalpel
6 test tubes
Test tube rack
Test tube holder
Water in 50ml beaker
Dropper
Means of labeling
Pestle and mortar
A hand lens
Dissecting needle / pins
A leafy twig of hibiscus plant with regular flowers labelled specimen S1
A leafy twig of bougainvillea with some mature flowers labeled specimen S2
An onion bulb with growing roots and growing aerial leaves labelled specimen p.
A shoot of tradescantia with flowers labeled specimen Q
Note: onion bulbs can be made to develop roots and leaves by planting
them in saw dust / sand.
Fleshly picked growing onions with roots intact can be used.
1.
Specimen Steps followed Identity
S1
S2
Q
X
Y
1a,2a,3b,4b,6b
1a,2a,3b,4a,5b,8a
1a,2b,
1a,2a,3a
1b,
Malvaceae
Nyactaginaceae
Commelinaceae
Graminae
Asteraceae
b) i) S1- Dicotyledonous
Q- Monocotyledonae
ii) S1 – Floral parts in threes (3, s0 multiples of 3/6 stamens / 6 anthers
/3 petals.
c) -Presence of large brightly coloured bracts / petals / perianth, to attract insects.
(Reject it is brightly coluored )
-Anthers and stigma enclosed in a tube, to be reached by insects
- Scented to attract insects.
.
85
d)
D1 – Continuous outline
- No shading
D2 – Proportionality and accuracy
- Long stigma (feathering) stigma thinner than stigma and ovary
- Oblong ovary
Magnification = Length of drawing / image (units)
Length of actual specimen (units)
= x (2-10)
* No units = Ref. answer
Wrong computation = Ref. answer
2. (a) T1 – Molar tooth
Reasons
i) Presence of cusps / ridges
ii) Presence of three roots
T2 - Incisors
Reasons
i) Chisel shaped / wide (sharp) edge / wedge shaped
Ref. one root
b) Cusps /ridges any upper white part
Crown – Black part below cusps
Neck - Boundary between white and black parts
Root – white lower part divided into 3
Enamel – All over the part seen
Dentine – Upper part below the cusps
c) J – vegetation, grass, shrubs, herbs, plants / leaves
Ref. vegetative , pasture, greens, grass eaters, herbivore, herbivorous but mark
reason.
Reasons
-Presence of diastema
- Absence of teeth (incisors and canines) at the front part of the upper jaw
-Presence of horny pad
.
86
-Presence of( premolars)cusps(for grinding vegetation)
K- Flesh/meat
Rej; carnivores/carnivorous, flesh eater but mark reason
Reasons
Presence of (pronounced) long curved sharp pointed canines for gripping /
tearing, holding/grasping prey
Ref; large
-Presence of carnassial teeth, for cutting and crushing bone
Inset – last on both sided
Photo – 2nd to the inside
e) J – 2 (10/3Co/1pm3/3m 3/3 ) = 32
K – 2 (13/3C1/1pm4/4m 2/3 ) =42
*teeth types must be identified using letters
Rej; If missing
*Demacating lines must be present
f) J
g) Refer to diagram area below main white part.
3. P(onion bulb with leaves and roots)
a) i) Inner succulent/ juicy /flesh while outer is dry
- Inner is thicker while outer is thin / membranous / scally
NB: Comparison must be seen otherwise deny a marks
ii) Inner swollen with food for storage and outer for protection against
dessication /mechanical injury / excessive loss of water/ microorganisms /
invasion by fungi.
Rej: Storage of water alone, & prevent water loss.
.
87
5.
Extract Procedure Observations Conclusion
Roots Add iodine No colour changed
colour of iodine
Brown yellow
retained / persist
Starch absent
Add benedicts
solution and boil/
heat/warm/place in a
hot water bath
Blue to green to
orange/ brown (acc.
brick red,ref.red
Reducing sugars
present/simple
sugars.
Bulbs Add iodine No colour change
colour of iodine
Starch absent
Add benedict
solution and boil
Green to yellow to
orange /brown
Reducing sugars
present
Aerial leaves Add iodine No colour change Starch absent
Add benedicts
solution and boil
Green to yellow to
orange to brown
Reducing sugars
present
* Green end – conclusions must be traces of reducing sugars
* Wrong procedures, deny observation and conclusion marks
c) Roots
- Presence of reducing sugars translocated from the bulb/aerial
Leaves, for provision of energy/respiration for growth and
development/respiration for growth and development/metabolic activities.
- Absence of starch because roots are not a storage organ.
ii) Bulb
- Presence of reducing sugars translocated from aerial leaves, for storage
to be stored.
- Absence of starch because fleshy leaves of the bulb do not
store starch (Stores Volatile oils)
Aerial leaves
- Presence of reducing sugars due to photosynthesis
- Absence of starch because the reducing sugars had not been
converted into starch.



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