KCSE 2019 General Science Paper 1 Questions with Marking Scheme

General Science Paper 1 (237/1)

SECTION A: BIOLOGY (34 marks)

Answer all the questions in this section in the spaces provided.

1. Name a branch of Biology that deals with the study of animals.(1 mark)
2. State two domestic applications of anaerobic respiration.(2 marks)
3.      
   1. Define the following terms as used in cell physiology:
      1. diffusion (1 mark)
      2. active transport (1 mark)
      3. State how support is achieved in young herbaceous plants.(1 mark) 
4. The diagram below represents a light microscope.
   
   
   1. Name the part labelled B.(1 mark)
   2. State the function of the part labelled A.(1 mark)
   3. Identify two organelles of an animal cell that would be seen under the light microscope.(2 marks)
5.          
   1. What is the meaning of the term excretion?(1 mark)
   2. State two reasons why excretion is necessary in animals.(2 marks)
6. The scientific name of a lion is Panthera Leo. Classify the organism under the following taxonomic units:
   1. class(1 mark)
   2. genus(1 mark)
7. Describe absorption of water from the soil by the root hairs.(3 marks)
8.       
   1. Name two members of the Kingdom Protoctista.(2 marks)
   2. Name two causes of liver cirrhosis.(2 marks)
9. Explain the significance of the following in the feeding of a mammal
   1. long tongue in herbivores (2 marks)
   2. canines in carnivores (1 mark)
10.         
    1. Explain the importance of gaseous exchange in humans.(2 marks)
    2. Name the main gaseous exchange structure in terrestrial plants.(1 mark)
11.      
    1. State the role of enzymes in metabolic processes.(1 mark)
    2. Explain the difference in energy requirements for a man and a woman of the same age.(2 marks)
12.        
    1. Explain why ventricles have thicker walls than the auricles.(2 marks)
    2. State the role of platelets in the human body.(1 mark)

SECTION B: CHEMISTRY (33 marks)

Answer all the questions in this section in the spaces provided.

13. Table 1 shows the pH values of various solutions. Use it to answer the questions that follow.
    Table 1
    

    Solution	F	E	D	H	G
    pH	1.0	7.0	12.0	6.5	10.5

    
    
    1. Identify the nature of the substance formed when F and D react.
    2. Identify the solution likely to be a:
       1. weak acid
       2. weak base
14.           
    1. A student prepared an insoluble salt by mixing two different salt solutions.
       1. Identify the method used to prepare the insoluble salt.(1 mark)
       2. Name one other method which can be used to prepare insoluble salts.(1 mark)
    2. Give one industrial use of sodium carbonate salt.(1 mark)
15.     
    1. A student used salt solution to remove blood stains from the school uniform. Name the method of separation the student applied.(1 mark)
    2. Anhydrous calcium chloride when left in the open forms a solution.
       1. Give the term used to describe such a substance.(1 mark)
       2. State one major application of such a substance.(1 mark)
16. A sample of hard water was divided into three portions. Table 2 shows the tests and observations made on each portion.
    Table 2
    

    Portion	Test	Observation
    1	1cm³ of soap added and shaken.	No lather was formed.
    2	Boiled and cooled. 1cm³ of soap was added and shaken.	No lather was formed.
    3	3cm³ of sodium carbonate was added and filtration done. 1cm³ of soap was added to the filtrate and shaken.	Lather formed immediately.

    
    
    1. Name the type of water hardness that was present in the sample.(1 mark)
    2. Identify two anions present in the water sample.(1 mark)
    3. Give one other substance that can be used for portion three instead of sodium carbonate.(1 mark)
17.           
    1. Distinguish between a covalent bond and a co-ordinate bond. (2 marks)
    2. Figure 1 is a diagram of ammonium ion.
       
       Name the type of bond labelled. (½ mark)
       1. P
       2. Q (2 mark)
18. Figure 2 represents a cooling curve for a liquid. Study it and answer the questions that follow.
    
    
    1. Explain why the temperature remained constant at region B and C.(2 marks)
    2. Give the physical state of the substance at region CK.(1 mark)
19.         
    1. Name the chemical family of the elements Helium, Neon and Aryon.(1 mark)
    2. Elements V, X, Y and Z belong to the same group in the periodic table. Table 3 gives information about the elements. Use it to answer the questions that follow. The letters do not represent the actual symbol of the elements.
       Table 3
       

       Element	Atomic radi (am)	Melting point (°C)
       V	0.152	180
       X	0.186	98
       Y	0.231	64
       Z	0.244	39

       Explain the trend in:
       1. atomic radii (1 mark)
       2. melting point (1 mark)
20.          
    1. Define the term electrolyte.(1 mark)
    2. Mercury and molten lead(II) bromide are good conductors of electricity. Explain how each one of them conducts electricity.(2 marks)
21.       
    1. Name two subatomic particles.(1 mark)
    2. Figure 3 shows part of a periodic table. Study it and answer the questions that follow. The letters do not represent the actual symbol of the elements.
       
       
       1. State the period to which element J belongs. (1 mark)
       2. Write the formula of the compound formed when element R reacts with element M.(1 mark)
       3. State the nature of the oxide formed by element N. (1 mark)
22. The set-ups I, II and III in Figure 4 shows different methods of gas collection used in the laboratory. Use it to answer the questions that follow.
    
    
    1. Identify the set-up used to collect dry hydrogen gas.(1 mark)
    2. State one property of the gas collected using set-up II.(1 mark)
    3. Name the method of gas collection in set-up I.(1 mark)
23. Figure 5 shows an experimental set-up used to investigate the active part of air. Study it and answer the questions that follow.
    
    
    1. In the space provided next to Figure 5 draw a diagram to show observations made at the end of the experiment.(2 marks)
    2. Explain the role of concentrated sodium hydroxide in the experiment.(1 mark)

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

24. Figure 6 shows a syringe containing a liquid.
    
    The mass of the syringe in Figure 6 when empty is 20g and when filled with some liquid, it weighs 30 g. Determine the density of the liquid. (the syringe is graduated in cm)(3 marks)
25. Explain why a drop of water placed on a clean glass surface spreads out.(2 marks)
26. A beaker of height 0.15 m is filled with a liquid of density 13600 kgm due to the liquid at the bottom of the beaker. (g = 10 Nkg). Determine the pressure(3 marks)
27. A student observed that dust particles illuminated by a beam of light in a room moved in a constant random motion. Explain this observation.(2 marks)
28. State the three modes of heat transfer.(3 marks)
29. State two reasons why water is not suitable for use as a thermometric liquid.(2 marks)
30. Figure 7 shows a uniform plank of length 2m and a weight of 75N. It is pivoted at a distance v from one end and balanced by a weight of 50N.
    
    Determine the value of y.(3 marks)
31. Figure 8 shows a stone resting on a horizontal surface.
    
    Explain the effect on the stability of the stone when the shaded part is chopped off.(2 marks)
32. A certain mass was attached to a spring. When the mass was removed, it was observed that the Spring did not regain its original length. State the reason for this observation.(1 mark)
33. A train moving at a velocity of 25 ms decelerates uniformly and comes to rest in 10 seconds. It then starts moving again after 5 seconds and accelerates uniformly to a velocity of 10 ms in 5 seconds. Sketch a velocity-time graph for the motion of the train within this period.(3 marks)
34. A spherical marble rolls freely on a floor until it comes to rest. State two factors that determine the distance it covers before stopping.(2 marks)
35. A stone is thrown vertically upwards and returns to the ground after some time.
    State the energy changes that take place.(2 marks)
36. It is observed that a boat sinks more in fresh water than in sea water. Explain this observation,(3 marks)
37. State two reasons why it is necessary to tidy up the laboratory after a physics experiment.(2 marks)

MARKING SCHEME

1. Zoology: RJ wrong spelling.
2.      
   • Production of fermented dairy products e.g. yoghurt;
   • Production of alcoholic beverages;
   • Production of leavened bread;
   • Fermented porridge:
3.           
   1.    
      1. Dillusion process by which particles/molecules move from a region ofhigh concentration to a region of low concentration;
      2. Active transport - process by which particles move from a region of low concentration to a region of high concentration with the use expenditure of energy:
   2. By cells becoming turgid/turgidity;
4.           
   1. Eye piece; Acc eye piccc lens.
   2. Concentrates/converge/condense light onto the specimen;
   3.    
      • Nucleus;
      • Cytoplasm;
      • Cell membrane;
5.               
   1. Elimination of waste product of metabolism from the body of a living organism through an excretory organ;
   2.           
      • Removes toxic/harmful substances from the body;
      • For osmoregulation; Acc. Water and salt balance
6.           
   1. Mammalia;
   2. Panthera;
7. Root hairs are surrounded by a film of water in the soil; the cell sap of the root hairs contains salts and sugars, hence is more concentrated/ hypertonic; Water is drawn into the root hairs by osmosis; across the semi-perineable membrane of the root hair cells;
8.         
   1.          
      • Amoeba;
      • Paramecium;
      • Euglena;
      • Plasmodium.
      • Spirogyra;
      • Chlamydomonas;
        (Any two) RJ wrong spelling. (b)
   2.             
      • Excessive intake of alcohol;
      • Infection by liver parasites/bacteria/ virus;
9.          
   1.          
      • Assist in cutting grass
      • Turning/manipulation of grass;
   2. Piercing/tearing/griping;
10.          
    1.        
       • Enables cells/tissues get oxygen for respiration;
       • Elimination of carbon (IV) oxide gas;
    2. Stomata/Stoma;
11.            
    1. Regulates the rate of metabolic processes (slow/accelerate/speed the rate);
    2. A man needs more energy than a woman; a man has more muscles/is more muscular, hence needs for more energy for constant muscular contraction/ relaxation; RJ Masculine,
12.           
    1. Ventricles pump blood for longer distances; thus need thick muscles to withstand high pressure/generate high pressure.
    2. Blood clotting/stops bleeding:
13.          
    1. Neutral Substance
    2.           
       • H
       • G
14.        
    1.         
       • Double decomposition/Precipitation
       • Direct synthesis
    2. Softening hard water, manufacture of glass
15.        
    1. Solvent extraction
    2.         
       1. Deliquescent 
       2.    
          • Manufacture of glass
          • Making detergents
          • As a drying agent
          • Manufacture of papers
            Any one @ 1 mark
16.       
    1. Permanent hardness
    2. Chloride ions, sulphate ions
    3. Ion exchange
17.             
    1.         
       • Covalent bond is formed by equal contribution of the shared electrons by the atoms.
       • Coordinate bond is forned when shared electrons are contributed by a single species of the atom.
    2.        
       
18.               
    1.       
       • Liquid = Solid phase
       • Temperature remain constant as Kinetic energy reduces, articles, form bonds with each other coming closer to form solids. Energy produced is used in bond formation/ substance is changing state
    2. Solid
19.           
    1. Noble gases
    2.               
       1. Atomic Radius Incrcascs downthe group due to increase in the number of energy levels.
       2. Melting point decreases down the group, the forces of attraction between atoms weakens hence decrease in melting point.
20.         
    1. Is a substance when in solution/melt conducts and decomposes by passage of an electric current.
    2. Mercury contains delocalized electrons (free electrons) which conduct electricity while Lead (II) bromide in molten state contains IONS (Pb2+, Br) which conduct electricity.
21.             
    1.           
       • Electrons
       • Protons
       • Neutrons
         Maximum 1 mark: two correct and above
    2.          
       • Period 2
       • RM
       • Neutral oxide
22.          
    1. III
    2. Denser than air
    3. Over water method
23.               
    1.    
       
    2. To absorb Carbon (IV) oxide produced after combustion.
24.  ρ=m/v
    =10/10
    1gcm³     
25. Adhesion between the water molecules and the glass surface is higher v than the cohesion between the water molecules hence the water spreads. OR cohesion is lower than adhesion. P= Phg
26. P=ρhg
    13600x0.15x10
    = 20,400Pa (N/m²)
27. The dust particles are bombarded/knocked/hit by invisible air✓ molecules which are in constant random motion.
28.          
    • Conduction
    • Convection
    • Radiation
29.           
    • It wets/sticks on glass
    • It has a low range of temperature /high freezing and low boiling point.
    • It expands unusually/ doesn't expand uniformly/anomalous expansion
    • It is a poor conductor of heat
    • Not visible (any 2)
30. Sum of clockwise moment=sum of anticlockwise moment
    F₁d₁ = f₂d₂
    50 x y=75(1- y)
    50 y = 75–75
    y = 75/125
    = 0.6m
31. The stone becomes less stable since the center of gravity shifts to the left unshaded part
32. The mass (force) stretched the spring beyond its elastic limit./elastic limit exceeded/break point
33.          
    
34.             
    • Frictional force between marble and floor/Nature of the floor.
    • Initial speed of the marble/initial force applied
    • Mass/weight of the marble.
    • Steepness
35. Kinetic energy → potential energy → kinetic energy
                                                      → (sound/heat)
36. The weight of the water displaced/up thrust in both cases is the same, the less dense (fresh water) ✓ more volume will be displaced.
37.               
    • Ensure proper storage of apparatus. /to locate apparatus easily.
    • To minimize risk of accidents/injuries.
    • Minimize breakages.