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2017 WASSCE (June) Integrated Science Paper Two – Essay
1. i) What is meant by the term seed dispersal?
ii) State three ways in which seed dispersal is important.
i) Define potential energy?
ii)A 400 g orange on a tree is 120 cm above the ground. Calculate the potential energy of the orange.
[g = 10ms^(-2)]
Give two examples each of the following
types of fertilizer:
i) inorganic fertilizers,
ii) organic fertilizers.
Three liquids, dilute acid solution, alkaline
solution and distilled water, were kept in
unlabelled identical reagent bottles.
Describe briefly a test that could be
performed to identify each of the liquids.
a)i) Seed dispersal is the spreading of seeds away from the parent plant.
ii) Ways in which seed dispersal is important
1. It prevents overcrowding of seedlings.
2. It prevents competition for resource between seedlings and parent plant (or
3. It allows plants to colonize new habitats or areas or lands.
4. It minimizes epidemic diseases among seedlings.
5. It prevents total destruction of plants by natural disasters (or it prevents plants from extinction)
6. It ensures that fewer plants are eaten by predators.
7. It results in diversity of vegetation in any given location (or it results in availability of plant species in many widely dispersed areas).
b)Potential energy is the energy possessed by a body due to its position above a
reference point (or the ground or relative to others).
ii) Calculation of potential energy
Mass is m = 400 g =400/1000 = 0.4 kg
Height is h = 120 cm = 120/100 =1.2 m
Acceleration due to gravity is g =10 ?ms?^(-2)
Potential energy = mgh = 0.4x10x1.2
? Potential energy = 4.8 J
c)Examples of inorganic fertilizers are:
• Sulphate of ammonia;
• Muriate of potash or sulphate of potash;
• Potassium nitrate;
• Rock phosphate;
• Sodium nitrate;
• Potassium chloride;
• Calcium nitrate;
• Ammonium nitrate
Examples of organic fertilizers are:
• Farmyard manure
• Pig dung
• Cow dung
• Green manure
• Fish manure
• Poultry droppings
d)Test for identification of liquids
Test: Red litmus paper and blue litmus paper are separately placed in each liquid.
Observation: Red litmus paper turns blue
implies that alkaline solution
has been identified.
Blue litmus paper turns red
implies that acid solution
has been identified.
Red and blue litmus paper
retain their colour implies
that distilled water has been
2. a)i) Explain the term ration as used in animal production. ii) Give three reasons for feeding animals with a balanced diet.
b) i) State three processes involved in purifying water to be supplied to a community. ii) What is the function of liquid ammonia in refrigerators?
c) i) What does the expression plastics are insulators mean? ii) A simple electrical circuit has a supply delivering 1.5 V. If the current in the circuit is 0.5 A, calculate the resistance.
d) Explain each of the following ecological terms;
Ration is the amount of total feed provided or served to an animal in a day or 24 hour period.
Reasons for feeding animals with balanced diet
• For proper growth;
• To prevent deficiency diseases;
• For production of healthy young ones;
• For repair of worn-out tissues;
• For energy;
• For replacement of worn-out tissues.
Processes involved in purification water
• Coagulation or flocculation or addition of alum;
• Chlorination or disinfection or sterilization;
• Taste and odour control by addition of calcium hydroxide;
• Corrosion and scale control.
Function liquid ammonia in refrigerators
It vaporizes and takes away heat or brings about cooling(or freezing).
Explanation of the expression plastics are insulators
Plastics do not easily conduct (or allow) electricity or heat to pass through them OR They do not conduct electricity or heat.
Calculation of resistance
V= IR ?(?)R = V/I = 1.5/0.5 = 3?
Explanation of the terms
i) Community – Community is a population of different species living in a particular habitat or interacting with each other.
ii) Population – Population is a group of organisms or individuals of same species occupying a particular habitat.
iii) Ecosphere – Ecosphere is part of the Earth or atmosphere that supports life. OR Ecosphere is the part of the universe habitable by living organisms.
3. a) i) Give three reasons why water is not a good thermometric liquid. ii) Give the reason why water is a good cooling agent in machines.
b) i) What is an enzyme?
ii) State three factors that affect the action of enzymes.
c) List three characteristics each of the following breeds of farm animals:
ii) dairy cattle;
d) i) Define the term hydrocarbon?
ii) Draw the structural formula of :
?) ethane ;
?) ethane .
Reasons for water not being a good thermometric liquid
1. It shows anomalous property or behavior.
2. Water clings to the capillary tubing or wets glass.
3. It vaporizes or condenses in the tubing.
4. It is transparent and therefore difficult to read its level through the glass.
5. It is a poor conductor of heat.
6. Water freezes at 0 ?C and boils at 100 ?C and hence range is not wide.
7. It has high specific heat capacity.
8. Water does not expand uniformly (over a wide range of temperature).
The reason for water being a good cooling agent in machines.
1. Water has a high specific heat capacity or it can absorb a lot of heat without breaking down itself.
2. It has a low viscosity or it flows easily.
3. It is neither basic nor acidic (or water is neutral).
An enzyme is a chemical that initiates or speeds up chemical reactions in living organisms (or an enzyme is a biological catalyst).
Factors that affect the action of enzymes are:
• pH or level of acidity or alkalinity;
• Substrate concentration;
• Enzyme concentration or surface area of substance;
• Product concentration;
• Inhibitors or activators.
c) i) Characteristics of layers
• large space between pelvic and breast bones.
• large or widc oval or moist or warm vent.
• bright or red or waxy or warm large combs and wattles.
• large and sofl or pliable space between pelvic bones (or flexible pubic bones).
• bright or large or prominent or sparkling eyes
• bright plumage.
• deep or soft abdomen without body fat.
• feathers ragged or dirty
• normally active or alert to their surroundings.
• They are heavy or large.
ii) Characteristics of dairy cattle
• They have well-developed or large udder.
• They have quiet character or they are docile.
• They are wedged-shaped or they are triangular in shape.
• They have large body capacity.
• They have thin long legs.
• They have slow growth rate.
A hydrocarbon is a compound that contains carbon and hydrogen only.
ii) ?) ethane ;
The structural formula of ethane is as follows:
[[ diagram require]]
?) ethane .
The structural formula of ethene is as follows:
[[ diagram require]]
4. a) i) What is meant by the pole of a magnet? ii) Draw the magnetic lines of force around a bar magnet.
b) List four post-harvest activities required in the preservation of maize.
c) Describe the processes that take place between pollination and seed formation in flowering plants.
d) Distinguish between:
i) an atom and an ion ;
ii) neutralization and esterification.
The pole of a magnet is the part of the magnet where the magnetic force is strongest OR It is the region of a magnet toward which the lines of magnetic induction converge or diverge. OR The pole of a magnet is either of the two ends of a magnet at which the field of the magnet is most intense.
The magnetic lines of force around a bar magnet is as follows:
[[ diagram require]]
Post-harvest activities required in the preservation of maize are:
• Threshing or shelling;
• Treatment with recommended chemical
Description of the processes that takes place between pollination and seed formation in flowering plants
1. Pollen grain absorbs water or germinates.
2. Pollen grain develops or grows into a pollen tube.
3. The pollen tube grows through the style and down the wall of the ovary carrying two nuclei (or tube nucleus and generative nucleus).
4. The generative nucleus divides to form two male gametes.
5. The pollen tube passes through the mycropyle of the ovule into the embryo sac where the tip dissolves setting free male gametes.
6. One male gamete fuses or unites with the egg nucleus or ovum to form the zygote which develops into the embryo of the future seed.
7. However, the other male gamete fuses with the polar nucleus (or endosperm nucleus) and the fertilizcd ovule becomes a seed.
1. An atom is an electrically neutral particle while an ion is a charged particle.
2. An atom is the smallest (indivisible) unit of matter and an ion is an atom with an electric charge.
3. In an atom, the number of protons and electrons are equal while in an ion, they are not equal.
4. An atom can take part in a chernical reaction while an ion cannot (or ions attract each other by electrostatic force).
1. Neutralization is a reaction between an acid and a base (to give salt and water only) while esterification is a reaction between an organic acid and an alkanol.
2. Neutralization is exothermic while esterification is endothermic.
3. Neutralization is fast (or not catalysed) while esterification is slow (requires a catalyst).
4. Neutralization produces salt and water only while esterification produces ester and water.
5. Neutralization is not reversible but esterification is reversible.
5. a) Define each of the following terms as associated with reproduction in humans:
b) Name the type of oxide formed when each of the following elements reacts with oxygen:
c) i) What is short-sightedness?
ii) Describe briefly how short-sightedness could be corrected?
d) Give four reasons why it is important to keep records during crop production.
a) i) Copulation- Copulation is the insertion of the penis into the vagina of a female.
ii) Ejaculation- Ejaculation is the release or the discharge of semen into the vagina during mating.
iii) Ovulation- Ovulation is the release of ripe or mature ovum or egg by the ovaries.
iv) Menstruation – Menstruation is the regular discharge of blood containing rnucosal tissue or dead tissue from the inner lining of the uterus (endometrum) through the vagina. OR Menstruation is the periodic or monthly discharge of blood from the vagina.
b) i) Type of oxide formed between sulphur and oxygen is acidic oxide.
ii) Type of oxide formed between sodium and oxygen is basic oxide.
iii) Type of oxide formed between zinc and oxygen is amphoteric oxide.
c) i) Short-sightedness is a defect of the eye that causes distant objects not to be seen clearly whereas near objects can be seen (clearly).
ii) Correction of short-sightedness
It can be corrected by use of concave (or diverging) lens no as to focus rays from distant objects onto the retina.
d) Reasons why farmers should keep records
1. To determine whether the enterprise is making profits or loss. OR To show income and expenditure.
2. Records show how much tax to pay.
3. It helps the farmer to plan or budget for the future (or making management decisions).
4. It helps to know total investment made into the farm business.
5. It helps the farmer to obtain loans.
6. To determine the amount of yield or productivity or sales made.
7. It gives information on the past or cropping history (or know when crops will be harvested).
8 It gives information on decision made earlier.
9. It provides reasons why things worked (or other things did not work).
10. To avoid repeating mistakes.
11. To measure progress in crop production.
12. For educating new generation of farmers.
13. To know when next to apply pest or disease control chemical.
14. To know when next to apply fertilizer.
15. For the farmer to know his or her weaknesses.
6. a) Calculate the mass of quicklime produced when 10 g of limestone is heated.
[Ca = 40; C = 12; 0 = 16]
The equation for the reaction is:
CaCO_3 > Ca0 + ?CO?_2
b) i) List three emissions of radioactivity.
ii) State the charge of each of the emissions listed in (i).
c) i) List three sources of organic matter in the soil.
ii) ) State two advantages of tilling as a method of land preparation in crop production.
d) Name four blood vessels associated with the human heart.
a) Calculation of mass of quicklime
Mass of CaCO_3, =40+12+(16×3) =100 g
Mass of Ca0 = 40+16 =56 g
100 g of CaCO_3 = 56 g of Ca0
?10 g of CaCO_3 = (56 ?10)/100 g of CaO
= 5.6 g of CaO
Method 2 (Using mole concept)
Molar mass of CaCO_3 = 100 g?mol
Molar mass of CaO = 56 g/mol
Amount of CaCO_3 is given by:
n(CaCO_3) = m/M= 10/100 = 0.1 mol
n ((CaCO_3))/(n(CaO)) = 1/1? n(CaO) = n(CaCO_3) = 0.1 mol
But n(CaO) = (m(CaO))/(M(CaO)) ? 0.1 = (m(CaO))/56
? m(CaO) = 56 ? 0.1 = 5.6 g
b) i) Emissions of radioactivity are:
1. Alpha particles (or ? particles)
2. Beta particles (or ? particles)
3 Gamma (or ? ) rays
4. Energy: no charge
ii) Charge on emissions are
1. Alpha particles (or radiation): +2
2. Beta particles (or radiation): or – 1)
3. Gamma rays (or radiation): no charge (or 0)
4. Energy: no charge
c) Sources of organic matter in the soil are:
• Dead or decaying plants or animals or other organisms
• Cell or tissue of soil organisms or living organisms.
• Substances synthesized by soil organisms
• Faeces or animal droppings or manure or compost.
ii) Advantages of tilling the soil
1. It helps to mix organic matter with the soil or it improves the fertility of the soil.
2. It loosens soil for easy root penetration and development.
3. For easy percolation or infiltration of water.
4. It aids aeration
5. It helps to control weeds better.
d) Names of blood vessels associated with the human heart are:
1. The aorta;
2. The pulmonary artey;
3. The pulmonary vein;
4. Superior vena cava;
5. Inferior vena cava;