• Tue. Jul 9th, 2024


    Jul 6, 2024


    BIOLOGY PAPER 1:231/1

    TIME:  2 HRS

    NAME:…………………………………………………… ADM.NO:………………..

    Instructions:  Answer all the questions in the spaces provided.

    1. What is the role of the following organelles?                                             (2mks)

    (a)        Ribosomes



    (b)       Secretory vesicle



    2          Give a reason why the coarse adjustment knob should not be used together with the high power objective lens.                                                                                              (1mk)




    3          What are the structural differences between mitochondria and chloroplasts?            (2mks)




    4          Which processes of living organisms depend on diffusion?                       (2mks)





    5          During a biological experiments, some form one students peeled a medium sized potato and bored a hole on top.  They then boiled the potato for 10 minutes then set up the experiment as shown below.

    (a)        Which physiological process was being investigated?                    (1MK)



    (b)(i)    State the expected results after 30 minutes.                       (1mk)



    (ii)        Give a reason for the results obtained in (b)(i) above.                   (2mks)




    6(a)      What is wilting?                     (1mk)



    (b)       State how temporary wilting can be advantageous to plants.                   (1mk)

    7          Epidermal cells of onion bulb were placed in three liquids A,B and C of different concentrations.  Sections were then placed on a glass slide and observed under the medium power of the microscope.

    The appearance of each is shown in the diagram A,B and C

    (a)        Identify the type of solution each cell had been placed.                            (3mks)

    A          –

    B          –

    C          –


    (b)       State the physiological term applied to the epidermal cell labeled B.                  (1mk)





    1. How are the following parts of a leaf adapted to their functions.

    (a)        cuticle and epidermis                                                (1mk)



    (b)       palisade mesophyll layer                               (1mk)



    (c)        Lamina                                                                        (1mk)



    9(a)      What are enzyme inhibitors                                     (1mk)



    (b)       Give three possible ways of terminating an enzyme – catalyzed reaction.                                                                                                                       (3mks)


    10(a)    What is the function of bile salts?                (1mk)



    (b)       Explain why the walls of the alimentary canal are not digested by the protein digestive enzymes.                                         (1mk)





    (c)        Name one carbohydrate found in a balanced diet, that enhances the process ofperistalsis.  (1mk)



    11(a)    Which apparatus is used to measure the rate of transpiration.    (1mk)



    (b)       State two precautions which should be taken when setting up the apparatus you have named in 11(a) above,                                      (2mks)




    12(a)    Give two reasons as to why clotting of blood is important.                                                                                                                                                                       (2mks)




    (b)       What is the role of platelets in the process of blood clotting.                   (1mk)



    (c)        Name two enzymes required in the process of blood clotting.                  (2mks)






    13        Using relevant examples distinguish between single and double circulatory systems.  (2mks)





    14        What is the role of vascular bundles in plant nutrition?                (3mks)

    15        What characteristics do mammalian lungs and the gills of bony fish have in common that enables them to exchange gases efficiently?           (3mks)








    16        The table below shows the percentage composition by volume of inhaled and exhaled air:-

    GasInhaled air (%)Exhaled air (%)
    Carbon  IV oxide0.034.0


    (a)        By what percentage is the carbon (iv) oxide concentration in exhaled air higher than inhaled air?                                                                                           (1mk)




    (b)       Explain the difference in the composition of the gases between inhaled and exhaled air.(2mks)






    17        The equation below shows what happens in cellular respiration.

    C18H36O2 + 26 O2                              18CO2 + H2O + ATP

    (a)        What do you understand by the term Respiratory Quotient?       (1mk)



    (b)(i)    Work out the RQ for the above substance.                                     (2mks)





    (ii)        Identify the substance being oxidized.                                             (1mk)



    (iii)       Which type of respiration is taking place?                                       (1mk)


    18(a)    Explain what is meant by the term osmoregulation.                      (1mk)



    (b)       State two ways in which glomerular filtrate is different from urine.                     (2mks)




    (c)        Which gland secretes antidiuretic hormone?                                                          (1mk)



    (d)       What causes diabetes mellitus?                   (1mk)


    19        The table provided shows the concentration of sodium and iodine in sea water and cell sap of a plant.

     Sodium ion concentrationIodine ion concentration
    Sea water25035
    Cell sap100550


    (a)(i)    Name the process through which the plant cells take up sodium ions.    (1mk)


    (ii)        Give a reason for your answer in (a)(i) above.                                             (1mk)



    (b)       If the plant was sprayed with a chemical that inhibits respiration

    (i)         Which of the two ions uptake will be affected?                              (1mk)



    (ii)        Give a reason for your answer in (b)(i) above                                 (1mk)










    20        The figure below represents an organism.




    (a)        Name the phylum and the class to which the organism belongs.                          (2mks)





    (b)       State two observable features that are used to place the organism in class (a) above. (2mks)







    21        The diagram below shows how gaseous exchange occurs across the gills of fish.

    (a)        What is the term used to describe the type of flow displayed above?     (1mk)



    (b)       What is the advantage of this flow system?                                    (1mk)


    1. c) Name an organ in human beings which display this flow system. (1mk)



    22        Using a microscope, a student counted 55 cells across a field of view whose diameter was 6000   Calculate the average length of one Cell.  Show your working.                      (1mk)




    23        The figure below shows the nuclear of a diploid cell during the early stages of cell division


    1. a) How many pairs of chromosomes does it have? (1mk)






    1. b) Draw a diagram to show how the nucleus of the daughter cell would look like after

    (i)         Mitosis                        (1mk)




    (ii)        Meiosis                                   (1mk)



    24        The diagram below represents a stage during cell division

    (a)(I)    Identify the stage of cell division.                 (1mk)


    (ii)        Give three reasons for your answer in (a)(i) above.






    (b)       Name the structures labeled M.                                           (1mk)

    25        The following chart shows a feeding relationship in an ecosystem.


    Green plants


    Grass hopper                                                                          Mice

    Lizards                                                                              Domestic cat

    Snakes                                                                                     Wild cat




    (a)        Construct two food chains ending with tertiary consumer in each case.  (2mks)





    (b)       Which organism has the largest variety of predator in the food web.      (1mk)



    (c)        Suggest three ways in which the ecosystem would be affected if there was prolonged drought.                                       (3mks)



    TERM 2

    1(a)      synthesize proteins/site of protein synthesis

    (b)       Transport of the packaged proteins and lipids

    2          This is because the high power objective lens is too near the slide.  It could damage the slide and the objective lens.




    –        Inner membrane is greatly folded into cristae in order to increase the surface area for respirationInner membrane is smooth
    –        Sausage shapedOval/egg shaped
    –        Has matrixHas stroma
    –        Lacks grana

    –        Lacks starch granules

    Has grana with chlorophyll

    Has starch granules


    4          –           gaseous exchange

    –           Absorption of soluble products of diffusion

    –           exchange of food substances and waste products between tissue fluid and cells

    –           Excretion of waste products

    (any 2)


    5            (a)        osmosis

    (b)(i)    salt crystals did not dissolve to form a solution/no observable change

    (ii)        Boiling killed the potato cells thereby by destroying their cell membranes which could no longer act as a semi permeable membrane;  Hence osmosis did not occur;

    6            Wilting occurs when the rate of transpiration exceeds the rate of water absorption causing the plants cells to lose their turgidity hence resulting to drooping.

    (b)         the droops of leaves seen during wilting is advantageous because it reduces the surface area exposed to the sunlight and atmosphere thus reducing the rate of transpiration.

    7(a)       A –       Isotonic solution

    B-         hypertonic solution

    C-         hypotonic solute

    (b)         plasmolysed cell

    8(a)       transparent to allow penetration of light to the palisade cells

    (b)         Contains large numbers of chloroplasts containing the chlorophyll which traps or absorbs light energy necessary for photosynthesis

    (c)          The lamina is broad and flat to provide a large surface area for absorption of carbon IV oxide and sunlight energy.

    9(a)       Enzyme inhibitors are substances that slow down or completely inhibit or stop the enzyme activity.

    (b)         – Raising the temperature

    -Altering the PH

    – Addition of an inhibitor

    10(a)     Emulsification of fats/breakdown of large fat droplets into tiny fat droplets to  increase their surface area for digestion.

    • Provide an alkaline medium in which the enzymes works best.

    (b) The alimentally canal is coated by mucus which forms a protective barrier against digestion by protein digesting enzymes

    • C) cellulose is roughage

    11(a)    Potometer

    (b)       – stem of the shoot should be cut and fixed into the potometer under water to prevent air entering into the xylem vessels                                     (any 2)

    –  Ensure that the whole apparatus is filled with water.

    –  All joints should be watertight

    12(a)    –  prevents loss of blood

    • Prevents entry of disease causing organisms

    (b)       Rupture on injured tissues to release thromboplastin which neutralize heparin(anticlotting factor).  It also activates prothrombin to thrombin

    (c)        thromboplastine/thrombokinase


    13        – single circulation is the type of circulation where blood passes through the heart only once in  a complete circulation eg. Fish

    –  double circulation is where blood enters the heart twice during a complete circulation.

    e.g  mammals

    14        -xylem – transports water and mineral salts to photosynthesizing cells

    – phloem transports the manufactured foods

    – VEINS – supports the leaf to be upright for the maximum absorption of light for photosynthesis

    15        -In both cases the respiratory surface i.e alveoli in the lungs and gill filaments in gills has a thin epithelial lining.                                                        (any 3)

    – in both cases the epithelial lining is moist

    – both are richly supplied with blood (are highly vascularised)

    – Both have large surface area offered by the large number of alveoli and gill filament respectively.

    – Both have an efficient ventilation mechanism.

    16(a)    4% – 0.03% = 3.97%

    (b)       Exhaled air has more carbon IV oxide than the inhaled air due to release of CO2 from the tissues inhaled air has higher concentration of Oxygen than the exhaled air.  This is because some of the oxygen diffuses into the blood stream and it is transported to the tissues for respiration.

    17(a)    Respiratory quotient refers to the ratio of the relationship between the amount of carbon IV oxide produced against the amount of oxygen used in respiration.

    (b)(i)    RQ =  = 0.6923



    (II)        Lipids(fat)

    (iii)    Aerobic respiration


    18(a)     Osmoregulation is the process through which the osmotic pressure of the body fluids is regulated.  It involves the regulation of the volume of water and solute contents in the body fluids

    1. b)
    UrineGlomerular filtrate
    1.  lacks glucoseHas glucose
    2.  lacks amino acidsHas amino acids
    3.  more water contentLow water content
    4.  high concentration of ureaLower concentration of urea



    1. c) Pituitary gland


    1. d) due to deficiency in insulin secretion from the pancreas malfunctioning of the pancreas so that it does not secrete adequate insulin


    19(a)(i)            Diffusion

    (ii)        sea water contains a high  concentration of sodium ions than the cell sap


    b(i)      iodine ions

    (ii)        sea water has a lower concentration of iodine ions than the cell hence requires energy to take up the iodine ions(by active transport)


    20(a)    phylum – Arthropoda

    Class –  Arachnida

    1. b) has four pairs of jointed leg

    Lacks antennae

    21(a)`counter current flow system

    (b)       It facilitates maximum gaseous exchange between the water flowing over the gills and the blood in the gills

    (c)        Kidneys i.e in the loop of Henle


    22         = 108.8 109


    23(a)                3


    (b)(i)                                                                                              (ii)




    24(a)(i)               Anaphase 1

    (ii)   –   Homologous chromosomes separate at the equator

    • Chromosomes start migrating to opposite poles

    –     sister chromatids attached  to spindle fibres at the centromeres.

    (b) Spindle fibres


    25(a)    Green plants                             mice                snakes              wild cat

    Green plants                                  grasshoppers              lizards                 Domestic cat

    (b)       Mice

    (c)        – green plants will dry up and decrease in numbers due to drought

    – The number of grass hoppers and mice would reduce due to starvation

    Secondary consumers i.e snakes and cats would die or migrate to other ecosystems