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BIOLOGY PRACTICAL QUESTIONS – NDHIWA DISTRICT
Each candidate will require the following:-
- Winged cockroach lablled R
- Tick labelled N
- Soldier termite labelled P
- Adult housefly labelled Q
- 10ml 20 volume hydrogen peroxide
- Pestle and mortar
- Spatula preferably a wooden one
- Scalpel
- Ruler caliberated in centimeters
- A medium size irish potato tubers labelled L
- Measuring cylinder (to measure up to 4mls)
- 2 boiling tubes
- 3 test-tubes
- Means of labeling (two each)
- A maize seedling with opened coleoptile
- Green leaves and should also have remains of grain labelled K seedlings grown in the sand on trays in plastic containers give good specimens
- Distilled water
- Iodine solution
- Benedicts solution
- Means of heating
1. You are provided with specimens labelled N, P, Q and R. Using the following characteristics and
in the order given only
- Number of legs
- Presence of wings
- Number of wings
a) Construct a three –step dichotomous key. Use the given letters for identification
(Specific names not required)
b) i) Using observable features only, state the phylum to which specimen R belongs
ii) Give three reasons for your answer in (b) (i) above
c) i) Using observable features only, classify specimen N in its class
ii) Give four reasons for your answer in (c) (i)
2. Study the photographs of some hydrophytes shown below. They show various adaptations
they have to overcome problems they are exposed to due to the nature of their habitats
i) What are hydrophytes?
ii) Name the structures of plants labelled 1 and 2
iii) State two problems which hydrophytes are faced with in their habitat
iv) With reference to the photographs, how are the hydrophytes adapted to solve each of the
problems you have stated in part 2 (iii) above?
v) State two internal adaptive features of the plants not shown in the photographs above
that enables them to live in their habitat
vi) What type of hydrophytes do the following plants represent?
R ……………………………….. S………………………………..
3. You are provided with a specimen labelled L and hydrogen peroxide
a) Cut two equal cubes whose sides are about 1cm from specimen L. Place one of the cubes into a
boiling tube labelled A. Crush the other cube using pestle and mortar. Place the crushed material
in another boiling tube labelled B.
To each boiling tube add 4ml of hydrogen peroxide
i) Record your observation
ii) Account for the result in (a) (i) above
iii) Write an equation for the break down of hydrogen peroxide
b) You are provided with a specimen labelled K. Separate the roots and leaves from the remains
of the grain. Crush the roots, leaves and the remains of the grain separately. To each
crushed materials add 1ml of water. Put the extract from the materials into separate test tubes
and label them using the reagents provided. Test for the food substances in each of the
extracts. Record the procedure, observation and conclusions in the table below:-
c) Account for the results obtained in (b) above
i) Roots
ii) Remains of grains
iii) Leaves
NDHIWA DISTRICT BIOLOGY PRACTICAL MARKING SCHEME (ANSWERS)
1. (a) With six legs …………..go to 2
(b) With eight legs ………….N
. (a) With wings …………go to 3
(b) without wings ………….P
(a) With one pair of wings …………..R
(b) With two pairs of wings ….Q
(b) (i)Arthropoda
(ii) – Presence of exoskeleton
– Segmented body
– Jointed appendages/legs, limbs )
(c) Arachnida
– 8 legs /4 pairs of legs
– Two body parts
– Lack of wings
-No antenna
2. (i) Plants which normally grow n fresh water/plants which normally grow in very we places
(ii) Part 1 – leaf stalk
part 2 – leaves
(iii) – Low O2 concentration
– Low light intensity
– Low mineral salt concentration content
– A lot of water
– Waves and currents
(iv) – Some (emergent) have broad leaves with numerous stomata on the upper surface to
increase transpiration
- Highly dissected leaves to increase surface area for absorption of maximum light CO2
for photosynthesis and gaseous exchange
- – Flowers are raised above the water to allow pollination
- – Some (floating ) have log fibrous roots to absorb mineral salts
- – Long leaf stalk to expose the eaves above water for photosynthesis
(v) – Many stomata on the upper surface to increase transpiration
– Numerous and sensitive chloroplasts that photosynthesize at low light intensity
– Large air filled issues /aerenchyma for buoyancy and gaseous exchange (store
O2 for respiration)
– Poorly developed vascular bundles to discourage water absorption
(vi) R -Submergent
S- Floaters
3. (a) (i) A – less/few bubbles/slow effervescence/fizzing/froth/foam
B- Rapid fizzing / bubbles
– (award 1mk for bubbling /effervescence in both A and B- Reject if bubbling
only appears in either A or B)
(ii) Large surface area in B than in A for enzymatic activity in
- Part (iii) tied to (i)
- Bubbles due to enzymatic activity (award only 1mk)
Hydrogen Peroxide water + Oxygen
- Chemical symbols alone or words alone
- Wrong enzyme, means wrong commitment
Accept:-H2O2 + catalase H2O O2 + Catalase
(b)
Procedure | Observation | Conclusion | |
Roots | Add one 2/3 drops of iodine (soln.) Accept add iodine or any other measurements | No color change/colour of iodine / brown /yellow colour | Starch absent |
To 1m of extract , add 1/2ml /equal amounts of | Blue to green
| Traces of reducing sugars | |
Benedict’s solution heat to boil | Yellow – orange/brown | Reducing sugar present ICCP simple sugar | |
Remains of grains | Add drops of iodine | Starch present | |
Add drops of Benedict’s solution | Green to yellow to orange/brown | Reducing sugar present | |
Leaves | Add iodine | No change | Starch absent |
Add Benedict’s | – Green to yellow to orange to brown | Reducing sugars present |
rej. – if for starch is written under procedure
– brick red
(c) Roots– Presence of reducing sugars translated from the remains of grain/as leaves; for
provision of energy /respiration/growth & development /metabolic activities e.g.
active transport;
– Absence of starch because roots are not storage organs.
Remains of grains
- Presence of reducing sugars translocated from the leaves/ hydrolyzed starch;
- Presence of starch because grain is a storage organ/some starch had not been hydrolyzed for germination /growth;
Leaves – Presence of reducing sugars due to photosynthesis; -Absence of starch because reducing sugars has not been converted to starch;