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Biology Paper 231/2 Kcse 1996 Question Paper
Biology Paper 231/2 Kcse 1996
Course:Secondary Level
Institution: Kcse question papers
Exam Year:1996
BIOLOGY PAPER 231/2 KCSE 1996
PRACTICAL MARKING SCHEME.
1. Confidential requirement: Specimen D – ‘sukuma wiki’ kale.
You are provided with a specimen labelled D, which is part of a plant.
a) (i) Using external features only, identify the part of plant leaf.
(ii) Give three reasons for your answer in a (i) above.
-Leaf blade / lamina
-Presence of petiole / mid – rib / leaf stalk.
-Presence of veins Rej; venation
b) Peel off the epidermis of the lower surface of the specimen. Mount a portion of
the epidermis in a drop of water on a microscope slide. Stain with methylene blue,
cover slip, observe the specimen under high power objective and count the
number of stomata in the field of view. Record the number of stomata in the table
below. Repeat the counting of stomata two times, each time moving the slide to
another field of view. Record the number of stomata for each field of view in the
table.
Field of view Number of stomata in Each field of view
Lower Upper epidermis
1. High power 28 13
2. High power 33 12
3. High power 30 13
Average number of
stomata
A- A(Must be lower than that
of upper epidermis)
Ref: Average if at least one count is wrong.
c) Repeat the procedure in (b) above using a peeling of the upper epidermis.
Record the number of stomata in the table.
d) Record the following from the microscope you used to count the stomata.
(i) Magnification of eyepiece lensx10/x15
(ii) Magnification of objective lens used x40 / x45
(iii) From the data in d(i) and (ii) above, calculate the total
Magnification. Show your working.
May = Eye x Objective
10x40 =400
15x45 = 675(Rej if working is not shown.)
e) Account for the average number of stomata on each side of the specimen.
Upper epidermis- fewer stomata / reduce transpiration / water loss / rate of
evaporation / exposed to direct sunlight.
Lower epidermis – more to increase rate of gaseous exchange // allow more
gaseous exchange / more stomata away from the sun to reduce rate of
transpiration.
2. You are provided with a specimen labeled H, which is a piece of mammalian
intestine. Squeeze the contents in the lumen into a test tube. Add 3ml of water and
shake the contents.
Reserve the piece of intestine for question (b)
a) (i) Use the reagents provided to test for the presence of
Starch, proteins and reducing sugars in the contents.
Record the procedures, observations and conclusions in
the table below.
Food substance procedure Observations Conclusion
Starch Iodine solution
added drop wise
Proteins Add NaOH to
solution then
copper sulphate
(1%) /CuSO4
+NaOH
Violet / purple colour
observed
Reducing
sugars
Reducing Sugars Colour changes from
Blue – green – yelloworange
/ Red ppt/Brick
red ppt.
Acc any of the colour.
Reducing
sugars present
(ii) Account for the results obtained in (a) (i) above
-No starch because it has been
Digested / converted / broken / changed to simple / reducing sugar.
-Reducing sugar present / incomplete digestion of protein
-Digestion / incomplete absorption.
No link / tied with table.
b) Cut specimen H along its length to expose the inner surface.
(i) Feel the inner and outer surfaces of the specimen. Record
your Observations.
Inner surface-
Slimmy / slippery / wavy / undulating / protrusion / projections/folds/s
wellings / lumps Rej: rough
Outer surface: Smooth
(ii) Account for your observations of the inner surface.
-Slimmy due to presence of mucus secreted by intestinal walls to protect
walls from enzyme digestion / lubricate the walls.
-Projections – presence of villi / finger like structure; for absorption of
food / folds to increase surface area for absorption.
3. Confidential requirement J: Fish /Tilapia
You are provided with a specimen labeled J.
a) Using observable features only, identify the class to which the
specimen belongs.
-Class Pisces (Rej Fish (es)
Use the observable features used to identify the class, which the
Specimen belongs.
(i) Presence of fins
(ii) Presence of scales / overlapping
(iii) Present gills/operculum
(iv) Presence of lateral line
b) Stroke the specimen on the lateral side from the head end to the
tail end. Repeat the stroking from tail end to head end.
(i) Record your observations
Tail – head – Rough
Head – tail – Smooth
(ii) Observe the arrangement of the scales .Record your Observations
-Scales overlap
-Free ends point backwards (owwte)
(iii) State the significance of the arrangement of the scales.
- minimize / reduce friction ( during motion)
- Prevent water contact with body / skin
- Protection
(Rej (iii) if (ii) is wrong.
c) Cut and remove the operculum to expose the gills. Remove one complete
gill from the specimen and place it in a Petri dish containing enough water
to cover it. Examine the gill using a hand lens.
Gill filament -Closed a top
-Arranged closely
-Proportionality
-Origin, gill bar
Gill bar -Continuous lines
-Curved
-Closed both ends
Gill rakes -Serrated
-Close to one another
-Origin – gill bar
-No shading
(ii) How is the gill adapted to its function?
-Many/numerous gill filaments to increase surface area for gaseous
exchange.
-Extensive vascularisation / many capillaries /blood vessels; for gaseous
exchange.
-Presence of rakers to filter / trap solid particles, which might damage the
gill filaments.
-Gill bar / arc / is bonny / cartilaginous / bony / hard / firm for support /
attachment gill filaments and / or strong rakers.
-Thin filaments; to facilitate diffusion of gases / to shorten distance for
diffusion of gases.
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