Kenya Certificate Of Secondary Education(KCSE 2013) General Science Paper 2 with Marking Scheme

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Kenya Certificate Of Secondary Education(KCSE 2013) General Science Paper 1 with Marking Scheme

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

In the table below, name the causative agent and state one symptom for each of the diseases indicated.(4 marks)

Disease Causative agent Symptom

Gonorrhoea

Candidiasis
1. State the functions of each of the following structures in human beings: (3 marks)
  1. ovary; ....................................................................................................................
  2. uterus; .....................................................................................................................
  3. Cowper's gland. ......................................................................................................
2. What is implantation? (1 mark)
The diagram below represents an external view of a maize grain.

Name the parts labelled A, B and C. (3 marks)
A ..................................................................
B ..................................................................
C ...................................................................
1. What is fertilisation? (2 marks)
2. With an example, describe discontinuous growth. (2 marks)
1. What is variation as used in biology? (1 mark)
2. Explain the following terms: (3 marks)
  1. haploidy;
  2. genotype;
  3. dominance.
State two applications of Genetics other than Genetic Counselling and Engineering. (2 marks)
1. Explain the following terms: (2 marks)
  1. niche; ......................................................................................................................
  2. carrying capacity. ...................................................................................................
2. Describe the origin of life by special creation. (2 marks)
Describe the structure of a sensory neurone. (3 marks)
1. State one survival value of geotropism to plants. (1 mark)
2. State two functions of auxins. (2 marks)
State the importance of support and movement in plants. (3 marks)
1. ...................................................................................................................................................
2. ..................................................................................................................................................
3. .................................................................................................................................................

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

1. Name the compound whose structure is given below. (1 mark)
2. Name two reagents that can be used to distinguish between alkanes and alkenes (1 mark)
3. State two uses of alkenes. (2 marks)
1. Name two common ores of iron. (1 mark)
2. Describe the reduction process in extraction of iron metal from its chief ore. (3 marks)
3. State any one use of wrought iron. (1 mark)
The flow chart below shows part of the process for manufacturing sulphuric (VI) acid.
1. Identify:
  1. X; ....................................................
  2. Y .................................................... (1 mark)
2. Name the catalyst used in the catalytic chamber. (1 mark)
3. Explain why sulphur(VI) oxide is first dissolved in concentrated sulphuric (VI) acid and not in water. (2 marks)
The graph below shows the rate of production of hydrogen gas when zinc granules are reacted with excess 2 M hydrochloric acid. The hydrogen gas produced was collected in a syringe.
1. Explain why part BC of the graph is horizontal. (2 marks)
2. On the same axes, sketch the curve expected if zinc powder of the same amount as the zinc granules was used. (1 mark)
3. What will be the effect of using excess 1 M hydrochloric acid instead of excess 2 M hydrochloric acid. (1 mark)
The set-up below was used to prepare chlorine gas. Use it to answer the questions that follow.
1. Name solid X. (1 mark)
2. Why was the chlorine gas produced in the set-up above passed through water before collection. (1 mark)
3. State two observations made when a moistened blue litmus paper was introduced into the gas jar containing chlorine gas. (1 mark)
The set-up below was used to investigate the rates of diffusion of ammonia and hydrogen chloride gases. Pieces of cotton wool were soaked in concentrated solutions of hydrochloric acid and ammonia respectively, and inserted into the glass tubes A and B of the same size at the same time. (H = 1.0; Cl = 35.5; N = 14.0).
1. In which tube did the universal indicator paper change first? Explain (2 marks)
2. State the observations made in tubes A and B after some time. (1 mark)
The diagram below represents a Jiko (burner) with burning charcoal.
1. 1. State two products formed in regions M and N. (1 mark)
    M ...........................................................................................................................
    N ............................................................................................................................
  2. What is the function of the part labelled L. (1 mark)
2. Why should people be discouraged from using charcoal in Kenya? (1 mark)
3. Give two advantages of using kerosene over charcoal as a fuel. (2 marks)
Given that 25 g of compound XCO₃ contains 0.25 moles, calculate the relative atomic mass of X. (C = 12.0; O = 16.0). (2 marks)
Describe how one can prepare one litre of 0.5 M magnesium nitrate solution.
(Mg = 24.0; N = 14.0; O = 16.0). (3 marks)

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

Figure 1 shows two rays of light from a point O at the bottom of a beaker full of water.The rays are refracted into the air at the surface of the water.

On the diagram, complete the path of the rays in air to show the position of the image O’ of the point. (3 marks)
State the reason why it is not possible to charge a metal rod while holding it with a bare hand.
Explain why a naked flame should be avoided in an enclosed place, where an acid accumulator is being charged. (2 marks)
A student is given a magnet with its ends marked N and S. She is also given a metal bar with its ends marked A and B. Explain how the student can prove that the metal bar is a magnet.
1. State what is meant by transverse waves. (1 mark)
2. Figure 2 shows how the displacement of a point varies with the time as a wave passes it.
  
  Determine:
  1. the amplitude. (1 mark)
  2. the frequency of the wave. (1 mark)
State two factors that affect the speed of sound in air. (2 marks)
1. State the reason why, when measuring current through a resistor, the ammeter is always connected in series and not in parallel with the resistor. (1 mark)
2. Figure 3, shows the scale of a voltmeter in a circuit. The scale of the voltmeter is in volts.
  
  State the reading shown. (1 mark)
Figure 4, shows a circuit consisting of two different coils A and B connected in series with a battery and a switch. The coils are immersed in equal amounts of water in beakers P and Q.

After switching on the circuit it is observed that water in Q boils before the water in P. State a reason for the observation. (1 mark)
Figure 5 shows a periscope being used to observe a player over a wall.
1. Complete the diagram to show the path of the ray from the player to the observer.
2. State the reason why the mirrors are placed at an angle of 45 . (1 mark) foci of the lens.
Figure 6 shows an object, O, placed infront of a diverging lens. F1 and F2 are the two principal

On the figure, draw a ray diagram to locate the image formed. (3 marks)
State two differences between hard X-rays and soft X-rays. (2 marks)
State two functions of the anode in the electron gun of a Cathode Ray Oscilloscope. (2 marks)
An electric bulb marked 75 W is used for 4 hours in a day. Determine the quantity of energy used in seven days in Kilowatt-hours. (3 marks)
Explain how pure silicon can be changed into a P-type semi-conductor by doping. (3 marks)
The mass of a 50 g radioactive material is found to have reduced to 6.25 g in 30 hours.
Determine the half life of the material. (3 marks)

MARKING SCHEME

SECTION A : BIOLOGY

Disease	Causative agent	Symptom
Gonorrhoea	Neiseria gonorrhea;	Itching of urethra / yellowish discharge /pain when urinating / vaginal odour; (2 marks)
Candidiasis	Candida albicans;	Itching and burning sensation of genital organs / white discharge from the vagina; (2 marks)

1. 1. Ovary - produces eggs / ova ; and female hormones;
    First one correct. (1 mark)
  2. Uterus - where the embryo develops;
    Contraction of the walls aids in the expulsion of the developed foetus during birth / parturition;
    First one correct. (1 mark)
  3. Cowper's gland - secrets an alkaline fluid that neutralizes the acidity along the urethra; (1 mark)
2. Attachment of the blastocyst to the walls of the uterus; by the villi.(3 marks)
1. Pericarp fused with testa;
2. Position of plumule;
3. Position of radicle; (1 mark)
1. The fusion of nucleus of male gamete / sperm with the nucleus of female gamete / ovum; to form a zygote; (2 marks)
2. In a discontinuous growth, the organism shows a number of periods of rapid growth followed by long periods when no growth occurs; e.g. Growth shown by arthropods; (an example of an arthropod like locust, crab etc). (2 marks)
1. Variation - the differences in traits that occur among members of the same species; (1 mark)
2. 1. Haploidy - Chromosome numbers that are half of the full complement; (1 mark)
  2. Genotype - refers to the genes that an organism contain / have for a particular trait. Genetic composition of an organism. (1 mark)
  3. Dominance - refers to the genes that determine the expression of the genetic trait in offspring;
    State where genes express/supress other genes. (1 mark)
Blood transfusion; plant / animal breeding; crime detection, disputed parentage (2 marks)
1. 1. Niche - the position that an organism occupies in a habitat / a functional
    description of a species role in a community / an expression of the range of all
    the factors that influence whether a species has all the resources it needs and whether it can carry out all the activities necessary for survival and reproducing; (1 mark)
  2. Carrying capacity - the maximum population / number of organisms of a particular speies that can be sustained by a given supply of resources; in an environment. (1 mark)
2. Special creation - life was brought into existence / created by a supreme being / God; life was created in perfect forms and have remained unchanged over time; (2 marks)
Sensory neurone - it has a cell body; situated off the axon.
Has receptor dendrites; located in the sensory organ.
Has long dendron and short axon;
Has myelin sheath; with nodes.
First three correct. (3 marks)
1. Geotropism - roots move towards source of water;
  Plants get anchored in the soil;
  First one correct. (1 mark)
2. Auxins - promote / initiates growth; adventitious root development; causes apical dominance;
  Prevent ageing / senescence;
  Responsible for tropic movements;
  First two correct. (2 marks)
Importance of support and movement in plants.
- At cellular level, like growth of pollen tube to bring about fertilization;
- At organ level such as tropic movements for survival value;
- Enable plants to get resources from the environment such as light / water nutrients;
- For escape to avoid harmful stimuli such as temperature;
- Bearing of leaves, fruits
  First three correct. (3 marks)

SECTION B : CHEMISTRY (33 marks)

1. But-l-ene. : (1)/butene (1 mark)
2. Bormine water
  Acidified potassium manganate (VII). : (1 2) /KMnO4 (1 mark)
3. Ripening of fruits.
  Manufacture of plastics.
  Manufacture of detergents
  Manufacture of ethan-1, 2-diol
  Manufacture of ethanol through hydrolysis
  (Any 2 correct.) (2 marks)
1. haematite : (1 2) (1 mark)
2. Coke in the furnace burns in the hot air to form carbon (IV) oxide : (1).
  Carbon (IV) oxide : (1) rises to the middle of the furnance and reacts
  with more coke to form carbon (II) oxide : (1). Carbon (II) oxide/ coke reduces the
  Iron (III) oxide to the Iron metal and carbon (IV) oxide. : (1) (3 marks)
3. Making Agricultural implements, nails, sheets, ornaments and horse-shoes. (1 mark)
  (Any 1 correct.)
1. X - Dry Sulphur (IV) oxide / dry SO₂ : (1 2)/sulphur dioxide
  / H₂S₂O₇ (1 mark)
2. Vanadium (V) oxide / Vanadium Pentoxide : (1)
  or Platinum/platinised asbestos.
3. Dissolving SO₂ in water is an exothermic reaction: that makes the acid to vaporise: (1). (1 mark)
1. The reaction is over : (1) since all the zinc : (1)granules have been used up. (2 marks)
2. On the graph : (1) (1 mark)
  
  ½ mark for rise in volume
  ½ mark for flattening at the same level
3. The rate of reaction will be : (1) slower. (1 mark)
1. Potassium manganate (VII)/CaOCl₂ : (1) (1 mark)
2. To remove the more soluble fumes of hydrogen : (1)chloride gas produced by the acid. (1 mark)
3. The moist blue litmus paper turns red. : (1 2)
  The red litmus paper is then bleached. : (1 2)
  (1 mark)
1. B / NH₃: (1)
  Ammonia gas (RMM 17) is less dense : than hydrogen chloride gas/hydrochloric asid gas (RMM 36.5) and hence diffused faster
2. In glass tube A, the universal indicator turned Red,:while in glass tube B, the universal indicator turned green. : (1 2) (1 mark)
1. 1. M: Carbon (IV) oxide (CO₂): N: Carbon (II) oxide (CO):(1 mark)
  2. To allow in air. : (1)(1 mark)
2. It brings about defforestration. : (1)
  global warming / Green house effect
  (Any 1 correct.) (1 mark)
3. - Easier to store : (1)/it is less bulky
  - Amount of energy produced per unit amount is higher in kerosene than charcoal. : (1) i.e. Kerosene has high heating value than charcoal.
  - It is a cleaner fuel compared to charcoal. (any 2 correct) (2 marks)
RFM = mass (g)
No. of moles
RFM = 25
0.25
= 100 : (1 2)
x + 60 = 100
x = 40 : (2 marks)
RFM of Mg(NO₃)2 = 148 : (1 2)
0.5 mole of Mg (NO3)2 = 0.5 x 148
= 74 g : (1 2)
Weigh 74 g of magnesium nitrate and place it in 500 cm³ beaker. : (1 2) Add about 400cm3 of distilled water and stir to dissolve Mg(NO₃)2 Transfer solution to a litre volumetric flask : (1 2). Rinse beaker and pour the solution into the volumetric flask. Top up the remaining volume with distilled water upto the mark. : (1 2) (3 marks)

SECTION C : PHYSICS

...
Any acquired charge flows through the body. :
During charging process both Oxygen and hydrogen gas are given off. :
The two can become explosive if exposed to a naked flame. :
The bar is a magnet if any of : it ends is repelled by the magnet North or South poles. :
1. Waves in which the vibration of the particles is always perpendicular to the direction of the wave travel. :
2. 1. - 0.75 m
  2. = 2.5 Hz.
- Density :
- Pressure :
- Humidity/temperature
  (any 2 correct)
1. All the current passing through resistor passes through the ammeter.
2. 2.4 V
Coil B has higher resistance than A.
1. 1. (i)
2. The ray successively passes through the tube (Ray is parallel to the walls of the tube). :
Hand x-rays have higher penetration power than soft x-ray. :
Hard x-rays are produced at higher accelerating voltage than soft x-ray. :
Hard x-rays have shorter wave length than soft x-rays. :
- Accelerating the electrons. :
- Focusing the electrons into a fine beam. :
  (any correct two)
E = Pt
= 1000⁷⁵ x 4 x 7
= 2.1 Kilowatt - hours
Pure silicon is doped with a trivalent element. : This results in the three valency electrons of the impurity pairing with electrons of silicon : and thus leaving a hole in the structure. :
50g → 25g → 12.5g → 6.5g
Three half lifes = 30 hrs
Half-life = 10 hrs