KCSE 2014 General Science Paper 1 Questions with Marking Scheme

QUESTIONS

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

1.              
   1. State one precaution that should be observed to protect bench tops when performing laboratory experiments. (1 mark)
   2. State the importance of transport in plants. (3 marks)
2. The diagram below represents a terrestrial plant.
   
   Based on the observation of the diagram:
   1. state the class to which the plant belongs: (1 mark)
   2. give a reason for your answer in 2 (a) above(1 mark)
3. A strip of raw pawpaw measuring 3 cm in length was immersed in a beaker of water. After 30 minutes the strip measured 3.2 cm.
   1. Explain the change in length.(2 marks)
   2. State one other observation that was made on the raw pawpaw strip at the end of the experiment.(1 mark)
4. The diagram below represents a plant cell as seen under high power of the light microscope.
   
   
   1. Based on observations of the diagram, give three reasons why it is a plant cell(3 marks)
   2. Name the organelle that carries out autotrophic nutrition in plants.(1 mark)
5.                      
   1. Give a reason in each case why enzymes are:
      1. catalysts;(1 mark)
      2. denatured by high temperatures.(1 mark)
   2. Explain the effect of temperature on the rate of photosynthesis.(2 marks)
6.                    
   1. State two reasons for carrying out vaccination.(2 marks)
   2. What is an allergic reaction?(1 mark)
7.                      
   1. Explain how age affects the rate of breathing in human beings.(2 marks)
   2. Name the causative agent of pulmonary tuberculosis.(1 mark)
8.                                   
   1. The diagrams below represents an experimental set-up that was used to investigate the process of respiration.
      
      
      1. State the aim of the investigation.(1 mark)
      2. State the purpose of rinsing the seeds in 1% formalin.(1 mark)
   2. Name two end products of digestion of a meal consisting of boiled rice and beans without oil.(2 marks)
9.                  
   1. Apart from thermoregulation, state two other roles of the skin in homeostasis(2 marks)
   2. How does amoeba maintain osmotic pressure when placed in hypotonic solution?(2 marks)
10. How is the liver involved in thermoregulation?(3 marks)

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

11. An experiment was set up to investigate the products of a burning candle as shown in the diagram below.
    
    
    1.                          
       1. State an observation made on the anhydrous copper (II) sulphate.(1 mark)
       2. Explain the observation made in a(i) above.(1 mark)
    2. What effect does the other product of burning candle have on the environment?(1 mark)
12. The diagram below is a set-up for the laboratory preparation of oxygen gas.
    
    
    1. Name substance Q(1 mark)
    2. Write an equation for the reaction that produces oxygen gas.(1 mark)
    3. Name two other reagents which can be used to prepare oxygen in the laboratory.(1 mark)
    4. Describe a laboratory test to show that the gas produced is oxygen.(1 mark)
13. The table below shows the pH values of solutions.
    

    solution	M	N	O	P
    pH	2	7	12	14

    1. Which solution is likely to be calcium hydroxide?(1 mark)
    2. Name the products formed when solution M reacts with sodium carbonate.(1 mark)
14.                  
    1.                    
       1. What is meant by the term "hygroscopic salt"?(1 mark)
       2. Give one example of an hygroscopic salt.(1 mark)
    2. State one use of sodium chloride other than being a food additive.(1 mark)
15. A student set up an experiment to investigate the effect of passing an electric current through lead (11) bromide using graphite electrodes as shown below.
    
    
    1. Identify a mistake in the set-up.(1 mark)
    2. Name the product formed at the anode after the mistake was corrected.(1 mark)
16.                    
    1. Hard water is healthy for drinking. Explain.(1 mark)
    2. Explain how ion-exchange is used to remove hardness in water.(2 marks)
17. A student used paper chromatography to separate pigments in different inks and obtained the results shown in the diagram below.
    
    
    1. Identify the inks that are in X.(1 mark)
    2. Which of the inks is least soluble?(1 mark)
18. Describe how sodium chloride can be obtained from a mixture of sulphur powder and sodium chloride.(3 marks)
19.                                  
    1. What is meant by the term "ionization energy"?(1 mark)
    2. Study the following table and use it to answer the questions that follow. The letters do not represent the actual symbols of the elements.
       

       Element	P	Q	R	S	T	U	V	W
       Electronic configuration	2.8.1	2.8.2	2.8.3	2.8.4	2.8.5	2.8.6	2.8.7	2.8.8
       1st ionization energy (kJ mol-1)	494	736	576	787	1017	1000	1255	1519

       1. From the table, ionization energies increase generally from element to element W. Explain.(2 marks)
       2. What types of oxides are formed by elements:
          1. R........................................(1 mark)
          2. U........................................(1 mark)
20. The table below shows the atomic numbers of elements of the periodic table represented by letters A to H. The letters are not the actual symbols of the elements.
    

    Elements	A	B	C	D	E	F	G	H
    Atomic number	3	7	8	9	10	11	12	13

    1. Select from the table two elements that belong to the same group.(1 mark)
    2. Write the formula of a compound formed between elements H and C.(1 mark)
    3. Which of the elements is monoatomic?(1 mark)
    4. Select an element that forms a divalent cation(1 mark)
21.                
    1. Identify the types of bonds in carbon (II) oxide molecule.(1 mark)
    2. Explain why graphite is used as a lubricant.(2 marks)

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

22. A stopwatch showed a reading of 0.05 s before the start button was pressed. When this stopwatch was used to measure the time taken by a stone to drop from the top of a building to the ground it recorded 3.68 s. Determine the time of fall.(2 marks)
23. Define the term density.(1 mark)
24. An object is found to have a weight of 12.5 N at a place where the acceleration due to gravity is 10^-2ms. Determine the mass of the object.(3 marks)
25. Explain how a drinking straw is used to draw a liquid from a bottle into the mouth.(3 marks)
26. State the reason why it is possible to compress a gas but not a liquid.(1 mark)
27.                  
    1. Overhead power cables between posts are allowed to sag a bit. Explain why this is necessary(2 marks)
    2. Figure 1 shows a bimetallic strip made of brass and iron.
       
       Figure 1
       In the space below, draw the appearance of the strip when heated (brass expands more than iron).(1 mark)
28. Define the term heat energy.(2 marks)
29. Figure 2 shows a uniform metre rule pivoted at the 20 cm mark and balanced by a weight of 4.5 N.
    
    Figure 2
    Determine the weight of the rule.(3 marks)
30. Figure 3 shows a cone resting on a flat surface.
    
    Figure 3
    1. Name the state of equilibrium of the cone.(1 mark)
    2. State the reason for the answer in (a) above.(1 mark)
31. Figure 4 shows a velocity - time graph for the motion of a certain body.
    
    Describe the motion of the body in the region:
    1. OA;(1 mark)
    2. AB;(1 mark)
    3. BC.(1 mark)
32. The length of a spring is 20 cm. When it is used to support a mass of 0.4 kg, its new length is 20.8 cm. Determine the spring constant. (take acceleration due to gravity g = 10 ms^-2)(3 marks)
33. It is observed that a passenger standing in a stationary truck tends to fall in a direction opposite to the motion of the truck when it suddenly starts moving. Explain this observation.(2 marks)
34. Figure 5 shows a cork floating in water and held in position by a thin thread attached to the bottom of the container
    
    Figure 5
    Name three forces acting on the cork.(3 marks)
35. State the energy changes that take place when a torch is switched on starting with the chemical energy in the cells.(2 marks)

MARKING SCHEME

1.                        
   1. Avoid spilling chemicals / acids which corrode bench tops;
      Avoid cutting specimens on bench tops because they scratch bench surfaces;
      Avoid placing hot objects on bench tops which may burn the tops. (1 mark)
   2. Distribution of nutrients / transport of nutrients only;
      Availability of raw materials for photosynthesis;
      Cooling effect to the plant;(3 marks)
2.                    
   1. Dicotyledonae; (1 mark)
   2. Leaves have net venation;
      Have tap root system;(1 mark)
3.                    
   1. There was movement of water molecules from the beaker into the strip of pawpaw by osmosis;
      because the strip tissue fluid was hypertonic / water in the beaker was hypotonic; (2 marks)
   2. The strip became rigid / hard / stiff / turgid / firm;
      The strip bent / curved;(1 mark)
4.                      
   1. Peripheral nucleus; Large central vacuole;
      Cell wall present; Has regular shape ; /chloroplast present(3 marks)
   2. Chloroplast; (1 mark)
5.                
   1.                    
      1. Control reaction rates; (1 mark)
      2. They are protein in nature; (1 mark)
   2. In low temperature the rate of photosynthesis is slow / rate increased with increase in temperature upto to optimum; beyond optimum temperature, rate decreases and eventually photosynthesis stops;(2 marks)
6.                          
   1. To prevent the spread of immunizable diseases;
      Enables the individual to develop immunity/to boost/increase immune system; against immunizable infections;(2 marks)
   2. Unusual response by the body cells to a foreign substance; (1 mark)
7.                  
   1. Metabolism is slower in older people; because of low oxygen demand; leading to lower rate of breathing. (vice versa)(2 marks)
   2. Micobacterium tuberculosis; (1 mark)
8.                  
   1.                      
      1. To find out if heat if produced by germinating seeds; as they respire. (1 mark)
      2. To kill bacteria that would respire producing heat;(1 mark)
   2. Glucose; Amino acids; (2 marks)
9.                
   1. Excretion of excess salts / water / waste products;
      Cooling of the body; by evaporating sweat.(2 marks)
   2. Excess water collects in contractile vacuoles;
      which discharge the contents to the exterior;(2 marks)
10. Liver has many metabolic activities which release heat; which is
    distributed by blood to maintain body temperature;
    When it is cold the liver metabolic activities increase /
    when it is hot the liver metabolic activities decrease;(3 marks)
11.                        
    1.                          
       1. - White ¹/₂ anydrous copper (II) Sulphate turns blue ¹/₂  (1 mark) 
       2. - Anhydrous copper (II) Sulphate combines with the water produced to form blue hydrated copper (II) Sulphate. : anhydrous Copper (II) Sulphate becomes hydrated.(1 mark) 
    2. It causes global warming / greenhouse effect. : (1 mark)
12.                    
    1. Q - Manganese (IV) oxide (MnO₂). : (1 mark)
                      MnO₂(s)
    2. 2H₂O₂(aq)   →     2H₂O(l) + O₂(g) : (1 mark)
                     catalyst
    3. Sodium peroxide and water
       OR
       Na₂O₂ and H₂O (1 mark)
       Penalise ¹/₂mark for absence or wrong symbols
    4. Oxygen relights / rekindles a glowing splint. :(1 mark)
13.                  
    1. Solution O; (1 mark)
    2. Salt / sodium salt, carbon (IV) oxide and water :(1 mark)
       1 mark - 3 correct
       1/2 mark - 2 correct
       0 mark - 1 correct
14.                    
    1.                  
       1. Hygroscopic salt refers to a salt that absorbs water from the atmosphere but does not form a solution. : (1 mark)
       2. KNO₃, anhydrous copper (II) sulphate (CuSO₄)/anhydrous magnesium chloride and anhydrous calcium chloride. :( ) 1 (1 mark)
    2. - Manufacture of chlorine
       - Manufacture of Sodium carbonate :
       - Extraction of sodium metal(1 mark)
15.                                
    1. Absence of source of heat :/ solid PbBr₂ instead of molten lead (II) bromide.(1 mark)
    2. Bromine gas / fumes : (1 mark)
16.                  
    1. - It provides calcium and magnesium ions ¹/₂  used by animals in formation ¹/₂  of strong bones, teeth and shells. (1 mark)
    2. Hard water is passed  through a column packed with a compound of sodium permuttit which exchanges Ca²⁺  and Mg²⁺ ions for Na⁺ ions. (2 marks)
17.                      
    1. Red and blue (1 mark)
    2. Brown ink  (1 mark) 
18. - Add water to the mixture, sodium chloride dissolves
    - Filter to obtain sulphur
    - Evaporate filtrate to obtain sodium chloride. (3 marks)
19.                  
    1. Ionization energy is the minimum energy required to completely remove the outermost electron from an atom in the gaseous state. (w.t.t.e) (1 mark)
    2.                        
       1. The atomic size decrease from P to W because of increase in the effective nuclear charge  hence the removal of the outermost electron across the period requires more energy  as the atomic size decreases. (2 marks)
       2.                      
          1. R - Amphoteric oxide ¹/₂ 
          2. U - Acidic oxide ¹/₂  (1 mark) 
20.                                  
    1. A ¹/₂  and F ¹/₂  (1 mark)
    2. H₂C₃  OR Al₂O₃ (1 mark)
    3. E  (1 mark) 
    4. G  (1 mark)
21.                  
    1. - Covalent bonds¹/₂ 
       - Coordinate / dative bond ¹/₂ 
       (¹/₂  mark for the structure only) (1 mark)
    2. Graphite exist in hexagonal layers which are held together by weak van der waals forces of attraction  These layers slip/slide over each other when compressed hence this makes it a good lubricant.  (2 marks)
22. Time of fall = 3.68 - 0.05 ; 1
    = 3.63s ; 1
23. Mass per unit volume / density ^mass/_volume / d = ^m/_v / δ ^m/_v
24. W = mg ; 1
    12.5 = m x 10 ; 1
    m = 1.25 kg ; 1
25. On sucking at the open end of the straw, the air inside is removed/sucked out; 1
    This lowers/reduces/decreases the pressure inside the straw; 1
    The atmospheric pressure now being higher than the pressure inside the straw; 1
    forces the liquid up the straw.
26. The intermolecular distances in gases are larger/greater/higher/larger/more than/bigger than in liquids; 1
27.                
    1. This is to allow for contraction ; during cold weather, 1 If this is not done the wires would break ; causing alot of damage. 1
    2.                          
       
28. Heat is energy transferred from place to place; 1 as a result of temperature difference; 1
    Form of energy; when absorbed/taken in, temperature rises; or when lost/given out, temperature f---
29. Sum of anticlockwise moments = Sum of clockwise moments/F₁d₁ = F₂d₂
    Let weight of rule be x ; 1
    x x 30 = 20 x 4.5 ; 1
    x = 20 x 4.5
             30
    = 3 N ; 1
30.                  
    1. Stable ; 1
    2. If the cone is slightly displaced, the position of the centre of gravity rises and falls /broad base/larger base/bigger base; 1 back to he same position when the displacing force is removed/vertical line passing through the c.o.g. falls within the base.
31.                            
    1. The body undergoes uniform/steady/constant acceleration /velocity increasing at uniform rate; 1
    2. The body moves with constant/steady/uniform velocity; 1 zero acceleration.
    3. The body moves with a uniform/steady/constant deceleration / velocity decreasing at uniform rate; 1 uniform negative acceleration.
32. Extension = 20.8 - 20 = 0.8 cm ; 1
    F = Ke
    400  x 10 = K x 0 8
    1000                100
    k = 4 x 100 = 500 Nm^-1
             0.8
33. This is caused by the tendency of the body to remain stationery (inertia); 1 since the body was initially at rest, it tends ; 1 to remain at rest as the truck moves forward.
34. - Weight/mg/gravitational 
    - Upthrust
    - Tension 
35. Chemical to electrical 
    Electrical to light / heat