General Science Paper 1 Questions and Answers - KCSE 2021 Past Papers

SECTION A: BIOLOGY (34 marks)

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

1.  
   1. Name two types of respiration that take place in an animal tissue. (2 marks)
   2. State two characteristics of living organisms that are specific to plants only. (2 marks)
2. Explain three features of respiratory surfaces that adapts them to their function. (3 marks)
3. The diagram below illustrates an experiment used to demonstrate water relationship in plant cells. X and Y are solutions in bags whose walls are semi-permeable.
   
   1. Identify the solution which is hypotonic to the liquid in the beaker. (1 mark)
   2. Account for the observation made in the bag containing solution X.  (2 marks)
4.  
   1. Explain the presence of non-return valves in the veins of a mammalian circulatory system. (2 marks)
   2. Name two proteins in the blood which are responsible for determining the blood group of a person. (2 marks)
5. Explain why glucose and protein are absent in urine of a healthy person.  (2 marks)
6. The diagram below represents a cell organelle.
   
   1. Identify the organelle.  (1 mark)
   2. How is the part labelled K adapted to its function?  (2 marks)
7. State three roles of saliva in the human digestive system. (3 marks)
8. Study the equation below and answer the questions that follow.
   
   1. Identify processes A and B.  (2 marks)
   2. In which cell organelle does process B take place?  (1 mark)
9.  
   1. Name the condition associated with the presence of sugar in urine. (1 mark)
   2. Name the two hormones involved in regulation of blood sugar in humans.  (2 marks)
   3. State two functions of the liver in humans.  (2 marks)
10.  
    1. Explain the following terms as used in blood transfusion:
       1. Universal donor (1 mark)
       2. Universal recipient (1 mark)
    2. State the branch of biology that deals with plants. (1 mark)
    3. State the role of ribosomes in the cell. (1 mark)

SECTION B:CHEMISTRY (33 marks)

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

11. Figure 1 is a setup to separate a mixture of substances B and C. Study it and answer the questions that follow.
    
    
    
    
    1. Identify apparatus A. (1 mark)
    2. State two properties that make substances B and C to separate.  (2 marks)
12. Fill in the spaces provided in Table 1. (2 marks)
                                          Table 1
    

    Name of the element	Chemical symbol
    Sodium
    	Hg

13.  
    1. Element X and Y are alkali metals. X is above Y in the periodic table. Explain the differences in their ionisation energies. (X and Y are not the actual symbols of the elements). (2 marks)
    2. The atomic number of element W is 13. Give the period and group to which the element belongs.
       1. Period  (1 mark)
       2. Group  (1 mark)
14.  
    1. Define the term mass number.  (1 mark)
    2. Use Table 2 to answer the question that follow.
                  Table 2 
       

       Substances

       Urea

       Sugar

       Lemon

       Identify the substance which is an electrolyte.  (1 mark)
15. Burning sodium metal was lowered into a gas jar containing a green gas E. A white solid F was formed.
    1. Identify:
       1. Gas E  (1 mark)
       2. Solid F (1 mark)
    2. Name the product formed if sodium metal was replaced with zinc metal. (1 mark)
    3. Write a chemical equation for the reaction taking place between zinc and gas E.  (1 mark)
16. Study the setup in Figure 2 and answer the questions that follow.
    
    
    1. State two observations made in the combustion tube   (2 marks)
    2. Give the chemical property of hydrogen gas in the setup (1 mark)
17.  
    1. What is an acid-base indicator? (1 mark)
    2. Complete the following general equation.  (1 mark)
       Metal  + Dilute Acid →
18. Study the flow chart in Figure 3 and answer the questions that follow.
    
    1. Identify
       1. Solid L (1 mark)
       2. Solid J.  (1 mark)
    2. Write a balanced chemical equation for the decomposition of solid L.  (1 mark)
19.  
    1. Using dot (•) and cross (x) diagram, illustrate the bonding formed when element P reacts with element Q. (Atomic number of P is 12 and that of Q is 17).  (2 marks)
    2. Name the type of bond in (a) (1 mark)
20.  
    1. The following equation shows the oxidation and reduction processes of lead(II) oxide and zinc.
       PbO_(s) + Zn_(s) → ZnO_(s) + Pb _(s)
       When the same reaction was repeated using magnesium oxide instead of lead(II) oxide, no product was formed. Explain. (2 marks)
    2. The following diagram in Figure 4 shows an iron water pipe fitted with blocks of zinc.
       
       1. Name the method used to prevent rusting of the iron water pipe. (1 mark)
       2. Give one other method used to prevent rusting. (1 mark)
21. Table 3 shows the volume of soap used with equal volumes of water from different sources to form lather.
                                  Table 3
    

    Water source	Volume of soap used
    H	12 cm3
    Z	2 cm3

    
    
    1. Identify which water source is hard. (1 mark)
    2. Describe how sodium carbonate can be used to soften hard water. (2 marks)

SECTION C: PHYSICS (33 marks)

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

22. State one laboratory safety rule that must be observed by a student when operating an electrical equipment.  (1 mark)
23. Figure 5 shows a measuring cylinder containing a liquid of mass 40 g.
    
    Determine:
    1. The volume of the liquid. (1 mark)
    2. The density of the liquid (3 marks)
24. Figure 6 shows a capillary tube dipped in water in a covered beaker.
    
    
    1. State the force that causes the rise of water in the tube. (1 mark)
    2. State what would happen to the level of water in the tube when the water in the beaker is heated for some time. (1 mark)
25. Figure 7 shows two pins P and Q that are to be driven into a bar soap.
    
    1. Equal forces are applied on pin P and pin Q. State which pin would be more easily driven into the bar soap. (1 mark)
    2. Explain the reason for your answer in 25(a) (2 marks)
26. Smoke particles enclosed in a transparent glass bottle are seen to be moving randomly when viewed through a microscope. Explain this observation. (2 marks)
27. Figure 8 shows a clinical thermometer.
    
    1. Identify the parts labelled K and L. (2 marks)
    2. State the reason why the scale does not go beyond 43°. (1 mark)
28. Figure 9 shows two insulated containers fitted with a thermometer. The two containers are filled with water at 100°. Container P is filled with water to the brim while container Q is partially full.
    
    1. State the thermometer which will have the lowest reading after some time. (1 mark)
    2. State the reason for the answer in 28(a). (1 mark)
29. A uniform metre rule weighing 6.4 N is pivoted at the 60 cm mark. Determine the point on should be suspended for the rule to be at equilibrium. thepere rule where a weight of 3.2 N should be for the rule to at be at equilibirum  (4 marks)
30.  
    1. Figure 10 shows an object resting on a flat surface.
       
       Identify its state of equilibrium.  (1 mark)
    2. State two way Page 9 male silbility or a boy can be increased.  (2 marks)
31. A student intends to make a steel spring that can support a large load without getting damaged. State three factors that the student should consider when making the spring.  (3 marks)
32. State the meaning of the term displacement.  (1 mark)
33. Figure 11 shows a bucket filled with water to the brim resting on a horizontal surface.
    
    It is observed that, when the bucket is suddenly moved forward by a force F, some water spills out in the backwards. State the reason why water spills.  (1 mark)
34. Figure 12 shows an inclined plane being used to move a load onto a platform of height h.
    
    State two adjustments that can be done to ensure that a lesser force is used in moving the load onto the platform. (2 marks)
35. Figure 13 (i) shows a Eureka can full of water and a measuring cylinder put below the spout. When an object of weight 0.5 N is placed in water, it floats and displaces some water into the measuring cylinder as shown in figure 9(ii).
    
    1. State the weight of water in the measuring cylinders.
    2. State the reason for the answer in 35(a).

MARKING SCHEME

BIOLOGY (SECTION A)
1	Aerobic respiration; Anaerobic respiration;             1 mark each                                                  Total 2 marks   Autotrophic nutrition; Localized movement;               1 mark each                                                  Total 2 marks	(2 marks)     (2 marks)
2	Moist; to dissolve diffused gases Highly vascularized; to increase surface area for transportation of gases. Thin membrane; to reduce diffusion distance across which diffusion occurs.                                                              1 mark each                                                               Total 3 marks N.B. Candidate must give the reason/justify the adaptation to earn the full mark.	(3 marks)
3	Solution Y;                                           Total 1 mark Solution X is hypertonic; it therefore draws in water from the surrounding solution Z by osmosis; (1 mark for hypertonic) (1 mark for explanation)                         Total 2 marks	(1 mark)    (2marks)
4	Blood in the veins flows at a low pressure; the non-return valves ensure there is no backflow;                                 Total 2 marks   Antigen (A,B and D); Antibody /(a,b);      1 mark each         Total 2 marks	(2 marks)   (2 marks)
5	Proteins have a large molecule and hence cannot pass through the small pores of glomerulus; Glucose is continuously needed in the body so it is immediately reabsorbed into the blood stream after ultrafiltration;                 1 mark each	(2marks)
6	Mitochondrion; RJ Mitochondria                       Total 1 mark   It is highly folded; to increase the surface area for attachment of respiratory (enzymes)                                                         Total 2 marks	(1 mark) (2 marks)
7	Moistens food facilitating enzymes activity. Its mucus lubricates food for easy swallowing. Contains ptyalin (salivary amylase) which digests starch to maltose. Contains lysosome enzyme which kill bacteria in the mouth.  Any 3 x 1 marks	(3 marks)
8	A - respiration (Aerobic)               Total 1 mark B - photosynthesis;                      Total 1 mark Chloroplast;	(2 marks) (1 mark)
9	Diabetes mellitus/glycosuria;                          Total 1 mark Insulin; glucagon;                                            Total 2 marks   Manufacture of the bile juice; Regulation of blood sugar of sugar; Deamination of amino acids; Storage of vitamins, glycogen and iron; Detoxification; Lipid metabolism;                                      Any 2 x 1  (2 marks)	(1 mark) (2 marks)       (2 marks)
10	Can donate blood to all other blood group types but can only receive blood from self; Can receive blood from all blood group types but can only donate to self;                                                                        Total 2 x 1 marks  Botany;                                                      1 mark Site for protein synthesis;                          1 mark	(2 marks)   (1 mark) (1 mark)
	SECTION B: CHEMISTRY
11	Separating funnel    Immiscibility Density	(1 mark) (1 mark) (1 mark)
12	Na Mercury	(1 mark) (1 mark)
13	X has higher Ionization Energy than Y. X has smaller atomic radius since the electrons are closer to the nuclear hence stronger nuclear attraction while Y electron, are far from the nuclear hence weaker nuclear attraction.   Period 3 Group III	(2 marks) (1 mark) (1 mark)
14	The sum total of the number of protons and neutrons in an atom Lemon	(1 mark) (1 mark)
15	Chlorine gas Sodium chloride Zinc chloride Zn(s) + Cl2(g) → ZnCl2(s)	(1 mark) (1 mark) (1 mark) (1 mark)
16	Copper (II) oxide changes colour from BLACK to BROWN Colourless liquid condenses on the cooler part of the tube. Reducing agent	(1 mark) (1 mark) (1 mark)
17	A substance that gives a definite colour in acid solution and a different colour in alkali solution. Metal + dilute acid → Salt + hydrogen gas	(1 mark) (1 mark)
18	Solid L - Zinc Nitrate Solid J - Zinc oxide 2Zn(NO3)2(s) → 2ZnO(s) + O2(g) + 4NO2(g)	(1 mark) (1 mark) (1 mark)
19	Ionic or electrovalent bond.	(1 mark)         (1 mark)
20	Zinc is below magnesium in the reactivity series and cannot reduce magnesium oxide.   Sacrificial protection. Oiling, painting, electroplating, galvanizing. ANY ONE	(2 marks)   (1 mark) (1 mark)
21	Water Source H Add Sodium Carbonate solution to water source to precipitate Calcium and Magnesium ions responsible for water hardness.	(1 mark) (2 marks)
22	Electrical equipment should not be touched with wet hands Turn off current before making any adjustments in the circuit  Any one 1 mark	(1 mark)
23	40 cm3   Density = Mass                 Volume              = 40                 40             = 1 gcm-3	(1 mark) (1 mark) (1 mark)
24	Adhesive forces. It will rise further/rises more/level of water in the tube increases more	(1 mark)
25	Q Q has a smaller area in contact with the soap hence larger http pressure	(2 marks)
26	They are being knocked by invisible air particles in constant random motion hence appears to be in constant random motion	(1 mark) (1 mark)
27	K- Bulb L- Capillary The normal body temperature is 37°C	(2 mark) (1 mark)
28	TQ Cooling occurs faster due to the space left which allows con- ventional current to set up.	(1 mark) (1 mark)
29	Sum of clockwise moment = Sum of anticlockwise moment  6.4 x 10 3.2 x X  X = 20 cm 3.2 N should be at (100 − 20) = 80 cm mark.	(1 mark) (1 mark) (1 mark)   (1 mark)
30	Unstable   Place the object to rest with the larger side (increase the base area) Increase the mass at the base/Increase weight	(1 mark)   (1 mark)
31	Diameter of the spring/thickness/cross-sectional area Length of the spring/number of turn Diameter of the steel wire/ thickness/cross-sectional area	(1 mark) (1 mark)   (1 mark)
32	Distance between any two points in a speciffied direction.	(1 mark)
33	Because of inertia hence some water tends to remain behind as the bucket is   pulled forward.	(1 mark)
34	Making the surface smoother/lubrication Reducing the angle of inclination/make plane longer	(1 mark)   (1 mark)
35	0.5 N A floating body displaces its own weight of the fluid in which it floats.	(1 mark)   (1 mark)