KCSE 2014 General Science Paper 2 Questions with Marking Scheme

Share via Whatsapp

« Previous Topic
KCSE 2014 General Science Paper 1 Questions with Marking Scheme

Download PDF for future reference Get on Whatsapp for 50/-

QUESTIONS

SECTION A: BIOLOGY (34 marks)
Answer ALL the questions in this section in the spaces provided.

Differentiate between ecology and ecosystem.(2 marks)
1. Name three air pollutants produced when charcoal is burnt in a poorly ventilated room.(3 marks)
2. Name the causative agent of amoebic dysentery.(1 mark)
The diagram below represents the human male reproductive system.
1. 1. Name the parts labelled K and L.
    K: (1 mark)
    L: (1 mark)
  2. State the role of the hormone produced by the testis.(1 mark)
2. What is meant by the term mitosis?(1 mark)
1. What is gestation period?(1 mark)
2. State two symptoms of Herpes simplex.(2 marks)
3. What is a genotype?(1 mark)
1. State the meaning of seed viability.(1 mark)
2. State two reasons why water is required for seed germination.(2 marks)
1. Giving an example, describe continuous growth in animals.(2 marks)
2. Distinguish between the terms homozygosity and heterozygosity.(2 marks)
1. What is chemical evolution?(2 marks)
2. State two ways in which meiosis is important in sexual reproduction.(2 marks)
State the meaning of the following terms:(3 marks)
1. irritability:
2. stimulus;
3. response.
Name three structures of the human ear that are involved in balance and posture.(3 marks)
State three functions of an endoskeleton.(3 marks)

SECTION B: CHEMISTRY (33 marks)
Answer ALL the questions in this section in the spaces provided.

The set-up shown below was used to investigate some properties of chlorine gas.
1. Explain why the level of water in the gas jar was higher than in the trough after some time.(1 mark)
2. 1. What would be observed if blue litmus paper was dipped into the water in the trough?(1 mark)
  2. Explain the observations made in b(i) above.(2 marks)
Calculate the number of moles contained in 30g of potassium nitrate (K = 39.0; N= 14.0; 0 = 16.0).(2 marks)
A balloon filled with air was tied and held above a trough containing hot water as shown in the diagram.
1. State the observation made on the balloon.(1 mark)
2. Explain the observation in (a) above.(2 marks)
1. What is meant by the term dilution?(1 mark)
2. Calculate the mass in grams contained in 25.0 cm³ of 0.2M sodium hydroxide solution (Na = 23.0; O = 16.0; H = 1.0).(2 marks)
1. Name one natural polymer and state its use.(1 mark)
  Natural polymer.
  Use.
2. State one advantage and one disadvantage of synthetic polymers.(1 mark)
  Advantage........................................................................................................
  Disadvantage........................................................................................................
1. Iron metal exists naturally in different ores. Other than haematite, name another common ore of iron.(1 mark)
2. During the extraction of iron metal, one of the reactions in the blast furnace is:
  Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)
  1. Name the raw material that is used to produce carbon (II) oxide.(1 mark)
  2. Iron metal produced in the reaction is in liquid state. Explain.(1 mark)
3. State with a reason, one use of stainless steel.(2 marks)
  Use:........................................................................................................
  Reason:........................................................................................................
The set-up shown below was used by a student to prepare sulphur (IV) oxide gas. Study it and answer the questions that follow.
1. 1. Identify a mistake on the set-up that will affect collection of sulphur (IV) oxide gas.(¹/₂ mark)
  2. How would the mistake be corrected?(¹/₂mark)
2. 1. State the use of concentrated sulphuric (VI) acid in the above set-up.(1 mark)
  2. What would happen if concentrated sulphuric (VI) acid was replaced with water?(1 mark)
  3. State one use of sulphur (IV) oxide gas.(1 mark)
When Potassium chloride was dissolved in water, the following change occurred.
KCl(s) + H₂O(l) → KCI(aq) ; ΔH = + 4.97 kJmol^-
1. 1. State the type of energy change in the above reaction.(1 mark)
  2. The above experiment was done in a boiling tube. State the observation that was made.(1 mark)
  3. Name the type of reaction in a(ii) above.(1 mark)
2. Name two factors considered when choosing a fuel.(2 marks)
1. Name the compound CH₃CHCHCH₃ (1 mark)
2. Name the type of reaction that takes place when the compound in (a) above is reacted with hydrogen chloride gas.(1 mark)
0.1 M hydrochloric acid was reacted with sodium thiosulphate solution. The time taken for the cross to disappear was recorded at different temperatures as shown on the graph.
1. Explain the shape of the curve.(1 mark)
2. What conclusion would be made from the curve?(1 mark)
3. Sketch another curve on the same axis that would be obtained when the concentration of hydrochloric acid is doubled.(1 mark)

SECTION C: PHYSICS (33 marks)
Answer ALL the questions in this section in the spaces provided.

Figure 1, shows an image I formed when an object O is placed infront of a convex mirror.

Figure 1
Complete the ray diagram to show the position of object O.(3 marks)
When a polythene rod is rubbed with a dry piece of cloth, and then brought near a negatively charged pith ball, the ball is observed to move away. Explain this observation.(2 marks)
1. Name one defect of a simple cell.(1 mark)
2. State how the defect in (a) above is minimized. (1 mark)
Figure 2 shows iron keepers used in storing bar magnets.

Figure 2
On the figure show the poles induced in the keepers.(1 mark)
Figure 3, shows an arrow which indicates the direction of travel of a wave in a medium. P, a particle of the medium is in the path of the wave.

Figure 3
In the space provided, sketch the diagram to show how the particle P moves when the wave is
1. transverse.
2. longitudinal(2 marks)
State two factors that affect the speed of sound in air.(2 marks)
Define the term potential difference.(1 mark)
Figure 4, shows two circuits X and Y in which two identical coils are used to heat two equal amounts of water. The two circuits are switched on at the same time.

Figure 4
1. State the circuit in which the water boils first.(1 mark)
2. Explain the answer in (a) above.(2 marks)
It is observed that a swimming pool full of water appears shallower than it actually is. Explain this observation.(3 marks)
Figure 5, shows an object O placed in front of a converging lens whose principal foci are F₁and F₂.

Figure 5
Using rays, complete the diagram to show the position of the image.(3 marks)
Figure 6, shows a displacement - time graph of a wave.

Figure 6
Determine the amplitude of the waveform.(1 mark)
An electric iron is rated 1500 W. Determine the cost of using the iron for 30 hours given that the cost of electricity is Ksh.8 per kilowatt hour.(3 marks)
1. State one way in which the path of a cathode ray can be changed.(1 mark)
2. The control grid in a cathode ray oscilloscope (CRO) is used to control the brightness of the spot on the screen. Explain how the brightness of the spot may be reduced.(2 marks)
State two ways in which the conductivity of a semiconductor can be increased.(2 marks)
Explain the danger of radioactive emissions on a human body.(2 marks)

MARKING SCHEME

Ecology is the study of interaction of organisms with one another and with their physical environment while Ecosystem is the sum total of the interactions linking organisms in a community with one another and with their environment.(2 marks)
1. Carbon (II) Oxide;
  Carbon (IV) Oxide;
  Carbon particles / soot;(3 marks)
2. Entamoeba histolytica;(1 mark)
1. 1. K - Prostate gland; L - Epididymis;(2 marks)
  2. Controls development of secondary sexual characteristics; leads to formation of spermatozoa/sperms;(1 mark)
2. It is a type of cell division giving rise to two identical diploid daughter cells; (1 mark)
1. The time between implantation and birth.(1 mark)
2. Genital sores /painless sores;
  Ulcers in affected areas;(2 marks)
3. It is the genetic constitution / make up of an organisms;(1 mark)
1. Ability of a seed to germinate; (1 mark)
2. It softens the seed coat;
  It hydrolyses stored food;
  It is a medium for enzyme activity / activates enzymes / transports dissolved nutrients; (2 marks)
1. In continuous growth, the animal grows all the way from fertilization till maturity; e.g. height in humans;(2 marks)
2. Homozygosity is a condition in which the gene pairs are similar / same / identical while Heterozygosity is a condition in which the gene pairs are different. (2 marks)
1. It is a theory on the origin of life; that suggests that life began from simple elements through complex compounds;(2 marks)
2. Meiosis leads to the formation of the gametes which are haploid;
  Meiosis ensures that the chromosomal constitution of offspring is the same as that of parents;(2 marks)
1. Irritability - ability to detect and respond to changes in the environment; (1 mark)
2. Stimulus - A detectable change in the environment capable of producing a response; (1 mark)
3. Response - the change in activity by the organism due to a stimulus.(1 mark)
Semicircular canals;
Utriculus;
Sacculus;(3 marks)
Give the body its shape;
Protects delicate internal organs;
Provides surface for attachment of muscles;
Produces / manufacture blood cells;
Stores calcium and phosphate ions;
Enables/allows movement;
Gives body balance and posture;
Supports the body wight. (3 marks)
1. Chlorine gas is slightly soluble in water hence water rises to occupy the space which was occupied by the dissolved gas. (1 mark)
2. 1. Turns red then bleached
    OR
    decolourised / turned white (1 mark)
  2. Chlorine gas dissolves in water to form acidic solution which turns blue to red.
    The red litmus paper is further decolourised / bleached due to presence of hypochlorous acid or chloric (I) acid.(2 marks)
Formula mass of KNO₃= 39 + 14 + 3 (16)
= 53 + 48
= 101 g
Number of moles in 30 g = 30/101
= 0.2970 moles (2 marks)
1. The balloon increased / expanded in size/volume.(1 mark)
2. Rise in temperature increases kinetic energy of air molecules in the balloon hence increased collisions / bombardments against the walls of the balloon, causing the balloon to expand. (2 marks)
1. A process where a solvent is increased/water is added/increased while the amount of solute remains constant in a given solution. (1 mark)
2. Formula mass of NaOH = 23 + 16 + 1 = 40 g
  Moles in 25cm³ = 0.2 x 25
  1000
  Mass in 25cm³ of NaOH = 0.2 x 25 x 40
  1000
  = 0.2 g (2 marks)
1. Natural polymers
  Cellulose / proteins / natural rubber/silk/wool.
  Uses
  Used for paper manufacturing, textiles
  - Rubber used in tyres, tubes
  - Proteins / cellulose in textiles.(1 mark)
2. 1. Advantages of synthetic polymer
    - Cheap / long lasting / moulded into many shapes.
    - Prevent / safe destruction of plants and animals.
    - Some are heat resistant / good insulators / non corrosive to acids / alkalis. (any one correct for ¹/₂)
  2. Disadvantage of synthetic polymer
    - Pollutants to the environment
    - Non-biodegradable
    - Costly to recycle
    - Burn producing poisonous gases. (1 mark) (any one correct at ¹/₂ mark) 2 marks
1. Magnetite / Pyrite.
  OR
  FeCO₃ / FeS (1 mark)
2. 1. Coke /Carbon (1 mark)
  2. Temperatures at the blast furnace are higher than the melting point of iron metal. (1 mark)
3. Use of stainless steel
  - Construction of bridges
  - In ships
  - Pipes, padlocks
  - Nails
  - Cutlery.(1 mark)
  (any one correct for 1 mark)
  Reason: Stainless steel does not rust /is resistant to corrosion. (1 mark)
1. 1. The thistle funnel is above the reagents and allows the gas to escape
    OR
    The thistle funnel doesn't have a tap. ( ¹/₂ mark)
  2. Use a dropping funnel / Dip the thistle funnel into the reagents. ( ¹/₂ mark)
2. 1. Used to dry the sulphur (IV) oxide/as a drying agent.
  2. The sulphur (IV) oxide gas would dissolve in the water, hence no gas would be collected in the gas jar.
3. Uses of sulphur (IV) oxide
  - Manufacture of sulphuric (VI) acid / sulphuric acid/ H₂SO₄ (l)
  - Bleaching agent
  - As a refrigerant
  - Fruit preservative
  - Infumigation/to kill germs (1 mark)
  (any one correct for 1 mark)
1. 1. Heat / enthalpy of solution (1 mark)
  2. The temperature would drop / boiling tube becomes cold. (1 mark)
  3. Endothermic reaction. (1 mark)
2. - Heat value
  - Cost of fuel
  - Availability
  - Environmentally friendly/less pollution
  - Cost of transporting the fuel/toxicity of fuel (2 marks)
  (Any two correct for 2 marks)
1. But - 2 - ene (1 mark)
2. Addition reaction (1 mark)
1. As the temperature rises, the time taken for the cross to disappear decreases.
  OR
  as the temperature decreases, the time taken for the cross to disappear increases. (1 mark)
2. The rate of reaction increases with rise in temperature.
  OR
  The rate of reaction decreases with decrease in temperature. (1 mark)
3. Diagram.
  
  (1 mark)
When the polythene rod is rubbed it acquires a negative charge; On bringing it near. 1 a negatively charged pith ball the two repel one another; 1
1. Polarization / local action/polarization/accummulation of hydrogen bubbles around the cathode 1
2. Polarization is minimised by adding depolarizer /pottasium dichromate/ local action/ dissolving of zinc/zinc being eaten / local action is minimised by coating zinc with mercury/amalgamation/using pure zinc. 1
1. Perpendicular oscilation.
2. Parallel along direction of the wave.
- Temperature; 1
- Humidity; 1
- Density of air
Work done in moving a unit charge from one point to another; 1
1. Circuit Y; 1
2. More current is flowing due to less; 1
  resistance in the circuit hence a greater heating effect; 1
- Light rays from the bottom of the pool are refracted at the interface; 1
- The ray of light from the bottom is bend away from the normal; 1
- The image of the bottom appears raised; 1
a = 4 m; 1
1500 ÷ 1000 = 1.5 kW ; 1
Cost of electricity = 1.5 x 30 x 8; 1
= Ksh.360 ; 1
1. By using a magnetic or electric field ; 1
2. - By increasing the grid potential so that/making the grid more negative; 1 fewer electrons reach the screen/more electrons are repelled; 1 34.
- By raising the temperature of the semiconductor; 1
- By doping the semiconductor ; 1
- Radiations have high energy ; 1 which damages the body cells; 1