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Biology Paper 231/2 K.C.S.E 2002 Practical Marking Scheme Question Paper

Biology Paper 231/2 K.C.S.E 2002 Practical Marking Scheme

Course:Secondary Level

Exam Year:2002

BIOLOGY PAPER 231/2 K.C.S.E 2002
PRACTICAL MARKING SCHEME
1. You are provided with specimens labeled D1, D2, D3 and D4. Examine them
(a) Draw and label specimens D1 and D2
Magnification X3 – X7
(b) Giving reasons state the agent or method of dispersal of the specimens.
Specimen Agent or method of
dispersal
Reasons
D1 Animal/ man Presence of hooks acc.
Hook like structures Rej.
Spikes, spines, thorns e.t.c
D2 Wind Presence, of pappus; light/
air like extensions
D3 Wind Presence of wings; light/
wing like structures
D4 Explosive Line of weakness along the
ovary wall.
(c) State the types of gynoeciums and placentation of specimen D4.
Type of (i) Gynoecium Monocarpus
(ii) Placentation Marginal
2. You are provided with olive oil, liquids labelled L1 and L2 and an Irish potato.
Label two test tubes A and B. Place 2 cm3 of water into each test tube. To test
tube labelled A, add 8 drops of liquid L1. Shake both test tubes. Allow to stand
for five minutes.
(a) (i) Record your observations
Test tube A
Oil is broken up into small droplets; which are dispersed/ spread/
throughout in liquid oil becomes emulsified/ debules/ tiny droplets; which
forms a suspension/ becomes cloudy/ turbid/Forms a white ppt.
Testy tube B
Oil floats on water / of mixing takes place/ Two separate/ immiscible
layers are seen.
(ii) Name the process that has taken place in test tube A.
Emulsification
(iii) State the significance of the process named in (a) (ii) above to increase
surface area.
(iv) Name the digestive juice in humans that has the same effect on oil as
liquid L1
I- Bile
Region of alimentary canal into which the juices is secreted
II- Duodenum
(b) Label two test tubes C and D. place 2cm3 of liquid L2 into each.
Add a drop of iodine into each test tube.
(i) Record your observation
Blue black/ black/ bluish/ blue/ grayish/ purple blue
(ii) Suggest the identity of L2
Starch
Cut out a tube whose sides are 1 cm from the Irish potato provided. Crush the cub
to obtain a paste. Place the paste into a test tube labelled C. Leave the set up for at
least 30 minutes.
(iii) Record your observation.
Contents of D remain unchanged/ blue black; blue black in C
Disappeared / fades light yellow/ brown/ orange
(iv) Account for the results in (b) (iii) above
Enzymes amylase; in potato breaks down starch; into sugars; that do not
give blue- black colours with iodine.
(c) (i) Cut another cube whose sides are 1 cm from the Irish potato.
Crush the cube. Place the crushed paste into test tube.
Carry out food test with the reagent provided.
Record the procedure and results
Procedure
Add equal amount of benedicts solution to the paste and boil; heat/ to boil/
warm.
Results
Grey/ yellow/ orange/ brown/ brick
(ii) Account for the results in (c) (i) above
Starch in potato is converted to maltose/ reducing sugar/ simple sugar; by enzyme
amylase/maltose (owwtte)
3. You are provided with specimens labelled Q and R. examine them.
(a) Giving reasons state the phylum of the specimens
Phylum Arthropoda
Reasons Exoskeleton/ chitinous
(b) (i) Name the class to which the specimen belong
Insecta.
(ii) State the features common to both specimens that are
Characteristics of the class mentioned in (b) (i) above.
- 3 body parts
- 3 pairs of legs
- A pair of antennae

Biology Paper 231/2 K.C.S.E 2002 Practical Marking Scheme Question Paper

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