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Biology Paper 2 K.C.S.E 2000 Practical Marking Scheme Question Paper
Biology Paper 2 K.C.S.E 2000 Practical Marking Scheme
Course:Secondary Level
Institution: Kcse question papers
Exam Year:2000
BIOLOGY PAPER 231/2 K.C.S.E 2000
PRACTICAL MARKING SCHEME
1 (a) You are provided with a specimen labeled D
(i) Name the specimen to which the specimen belong Arthropoda
(ii) State three characteristics found in the members belonging to the phylum
- presence of exoskeleton/ Ectoskeleton
- Jointed limbs/ appendages/ legs
- Segmented body parts
(b) (i) Name the class to which the specimen belongs
Insecta
(ii) State four characteristics found in the members of class
Body divided into three ( head, thorax, and abdomen)
Three pairs ( six legs)
One pair ( 2 antennae)
Presence of spiracles/ breath through spiracles
Compound eyes ( one pair)
(c) Remove, draw, and label the mouth parts used for:
(i) Biting and chewing food
(ii) Hold food
(iii) Feeling and tasting food
(d) Examine the wings of the specimen. State the differences between them.
Forewing/outer wing Hind wing/ Inner wing
- Hard - Soft/ Membranous
- Narrow/ small surface/ small - Wide/ broad/ large surface area
- Stiff/ rigid/ inflexible - Flexible/ can fold
- Opaque - Translucent
2. Confidential requirements:
Specimens:
G- onion bulb (Sprouting) E- Taproot/Taproot tuber/ swollen tap root/main
root/Carrot root hairs/ F- stem tuber
You are provided with specimens labelled E, F and G.
(a) With reasons state which part of plant are specimens E, F and G.
E- carrot root hairs
Reasons
Presence of lateral roots
Short stem. Swollen worth food
F- Irish Potato
Reasons
F- Stem tuber
- Presence of lateral buds/ auxiliary/ auxiliary buds
- Presence of scale leaves
- Swollen with food
G- Bulb/ Onion bulb/ Onion plant bulb
Reasons
Scale leaves / scaly leaves
Short stem/ flattered stem
Fleshy leaf bases/ leaves swollen with food.
Make a longitudinal section through G
(b) Draw and label the specimen
(c) (i) name the vitamin present in specimen E
Vitamin A retinal
(ii) What are two functions of the vitamin named in (c) (i) above.
Protein of skin and cornea form dying
Synthesis of Rhodopsin pigment
Improves night vision/ vision in poor light
(d) State three differences in specimen F and G
F G
- Food stored in stem - Food stored in leaves
- Swollen stem - small short/flattened stem
- Rudimentary/ not well
Developed scaly leaves - Dry papery/ well developed scale leaves
- Small/ inconspicuous scale leaves - Presence of adventitious roots
- Absence of adventitious roots
3. You are provided with a substance labelled H. Filter the substance and collect
filtrate. Filtration is expected to be complete after about 30 minutes. Using the
reagents provided, test for the food substances in the residue and the filtrate.
Record your procedures, observations and conclusions in the table below.
Residue
Food substance procedure Observations Conclusion
starch Add a drop of
iodine
Colour of iodine/yellow/
orange/ brown/ reddish
brown / no colour change
Starch absent
proteins Add NaOH then a
drop of 1% CuSO4
and shake
Purple violet colour Presence of
proteins
Reducing Simple
sugars
Add benedict’s
solution and heat in
warm water bath
Green colour/
yellow/Orange/
red/brown/ colour
Traces of reducing
sugar of colour
change is greenish.
Reducing/ Simple
sugars present
Filtrate
Food Substance Procedure Observations Conclusion
Starch Add a drop of
iodine
No colour change/colour
of iodine/ yellow/ brown/
orange/ reddish brown
colour
No starch present
Protein Add NaoH then
CuSO4 and shake
Blue colour/ light blue/
No colour change/ Colour
of copper sulphate
retained. Purple
colouration
Absence of proteins
or presence of
proteins according
to observations
Reducing/ simple
sugars
Add Benedict’s
solution and heat/
place in a warm
water bath
Green/ yellow/ orange /
red/ brick red ppt
Greenish
colouration
Traces of reducing/
simple sugars
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