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2011 WASSCE (November) Integrated Science Practicals
1. (a) i) Describe briefly how a mixture of iodine crystals and sand could be separated in the laboratory.
iii) Name the method of separating the mixture named in (i).
b) Figure 1 is an illustration of three test tubes labeled A, B, and C used in a simple experiment in the laboratory.
Test tube A contains 5.0 m of 0.1M HCl solution mixed with three drops of methyl orange indicator. Test tube B contains 10.0cm OF 0.1 M NaOH solutions mixed with three drops of methyl orange indicator. Test tube C contains a solution obtained by adding the content in a test tube A to that in test tube B.
i) State the colour of the solution in
?) test tube A,
?) Test tube B,
?) Test tube C,
ii) Give the reason for the answer in (i) and (?).
iii) State the type of reaction that takes place when the solution in test tube A was added to the solution in test tube B.
iv) Write a balanced chemical equation for the reaction in (iii)
v) Name two other indicators which could have been used in this experiment.
a) i) Separation of mixture of iodine crystals and sand
– put the mixture in evaporating dish or test tube or beaker
– Cover beaker or test tube with a watch glass or filter paper or inverted funnel.
– Heat gently over a low flame or using the sun
– Iodine vaporizes or sublimes after sometime
– Deposit of iodine is seen on the watch glass or filter paper or top of the test tube
– Heating is continued until no violet vapour is seen to be coming from the mixture
– The sand is left at the top of the container.
– Put the mixture in evaporating dish or test tube or beaker
– Mix mixture with KI solution to dissolve iodine
– Filter to obtain sand
– Recrystalise iodine from solution
– Dry solid iodine.
b) i) ?) Red or pink
?) Yellow or orange
?) Yellow or orange
ii) NaOH reacts with HCl by 1 : 1 ratio and the amount of NaOH used in solution C being twice as much as the amount of HCl, the resulting solution is basic.
iii) Neutralization reaction
iv) NaOH + HCl –> NaCl + H2O
v) Indicators which could have been used in this experiment
– Universal indicator
– Litmus paper
2. Fig 2a is an illustration of an electrical circuit used to investigate the relationship between the potential difference, V, and length, L of a wire
The potential difference V = V1 across the corresponding length L = L1, of the wire was determined. The experiment was repeated for various length L2, L3, L4, and L5 of wire and their corresponding potential difference V2, V3, V4, and V5 were read
Fig. 2b represents the potential difference V = V1, V2, V3, V4, and V and fig 2c represents the length L= L1, L2,L3, L4 and L5
a) i) Measure and record the length L = L1, L2, L3, L4, and L5
ii) Read and record the corresponding potential difference, V = V1, V2, V3, V4 and V5
iii) Tabulate results obtained in (i) and (ii) as shown below
V/V | | | | | |
L/cm | | | | | |
b) Plot a graph with potential difference, V, on the vertical axis and the length , L, of wire on the horizontal axis.
c) i) Determine the slope of the graph
ii) State the relationship between the potential difference V, and length L, of the wire.
V/V |V1 = 0.13 |V2 = 0.18 |V3 = 0.23 |V4 = 0.28 |V5 = 0.33
L/cm |L1 = 5 |L2 = 7.5 |L3 = 10.0 |L4 = 12.5 |L5 = 15.0
i) From the graph slope = CB/AC = ((0.31-0.05))/(14-1)cm = 0.26V/13cm = 0.02 V cm-1
ii) The potential difference (pd), V increases by 0.02 V for every centimeter increase in length, L of the wire or V is directly proportional to
3. 3. a) Fig. 3 is an illustration of structures associated with plants.
Study the figure carefully and answer the questions that follow
i) Identify the structure A and B.
ii) ?) Name each of the parts labeled I, II, III, IV, V, VI, VII and VIII.
?) State one function of each of the parts labeled II and IV.
iii) State the relationship between structure A and structure B
iv) State the mode of dispersal of the part labeled VIII.
v) Name one plant which produces structures similar to B.
c) Fig. 4 is an illustration of an experimental set-up to show that heat is given out during germination of seeds. Equal quantities of seeds were put in A and B. the seeds in A were boiled for few minutes and seeds in B were soaked in distilled water for few hours. Both seeds in A and B were sprinkled with formalin and were left for 24 hours.
i) Name the parts labeled I, II, III, and IV.
ii) What would be observed in each of set-ups A and B after 24 hours?
iii) Give reasons for the observations in (ii)
iv) State two precautions that would be taken during the experiment.
a) i) A – Flower
B – Fruit
ii) ?) I – Receptacle
II – Filament
III – Anther
IV – Style
V – Ovules
VI – Sepal
VII – Pericarp or fruit wall
VIII – Seed
?) II (Filament) supports the anther or holds the anther in position
IV (style) connects the stigma to the ovary or helps as passage of the pollen tube into the ovule or holds stigma in position.
iii) Structure B (fruit) develops from structure A (flower).
iv) Explosive mechanisms
v) Plants that produce similar structures in B (fruit)
– Caesalpinea or pride of barbarbos
b) i) I – Thermos or vacuum flask
II – Cotton wool
III – Thermometer
IV – Retort stand
ii) Observation in set- up A
No appreciable increase in temperature or thermometer reading remains the same.
Observation in set- up B
There is significant increase in temperature
iii) Reason for observation in set- up A
The bean seeds were killed by boiling, therefore no germination took place for heat to be released
Reason for observation in set – up B
Germination occurs to release heat hence the temperature increases.
– Cotton wool to prevent heat loss or gain
– Application of formalin to prevent fungal growth or decay of seeds
4. Fig 5. Is an illustration of the digestive system of farm animals.
Study the figure carefully and answer the questions that follow.
a) i) Name the parts labeled I, II, III, IV, V, and VI.
II) State one function each of the parts labelled I, V, and VI
b) i) Name two farm animals that possess the digestive system illustrated.
ii) What is the general name given to the farm animals in (i)
c) i) Name one parasite that affects the part labeled IV
ii) State two ways of controlling the part labeled in (i).
a) i) I – Oesophagus
II – Rumen
III – Abomasum
IV – Duodenum or small intestines
V – Colon or large intestines
VI – Rectum
ii) Functions of labelled parts
I – Serves as the passage of food items from the mouth into the rumen or stomach
V – Absorbs water into the blood stream
VI – For the temporary storage of undigested food or faeces.
b) i) Farm animals that possess the digestive system illustrated
– Cattle or cow
c) i) Parasites that affects the part labeled IV
– Round worm or Ascaris lumbriciodes
ii) Ways of controlling tapeworm
– Implementation of proper sanitary conditions
– Examination of meat for sale by health inspectors
– Meat should be well cooked
– Treating of infected persons with recommended drugs
Ways of controlling roundworm
– Ensuring that rivers and ponds are not contaminated by infected urine and faeces
– Treatment of infected persons with recommended drugs
– Protect food from flies
– Observation of personal hygiene or washing hands after visiting the toilet
Ways of controlling hookworm
– Proper use of latrines
– Protection of food from flies
– Proper disposal of faeces
– Wearing shoes or sandals
– Treatment of infected persons with recommended drugs