KCSE Past Papers 2013 Biology Paper 1 (231/1)

  • Biology Paper 1 (231/1)

    1 a)Is when the rate of water loss is more than the rate of absorption and the plant droops; l mark

    b)The rate of active transport increases with increase intemperature up to the optimum temperature; 1 mark

    Further increase in temperature slows down the rate of active transport until it stops because it denatures enzymes; _ 1 mark

    2 a)Animal cell; 1 mark

    b)Has cell membrane only/has no cell wall;


  • Has numerous small vacuoles; 
  • Has central nucleus; Max. 2 marksc) Consists of many similar cells performing the same function; l mark

    3 a)Have mammary glands; have extemal ears/pinna;

    Body covered with fur/hair; ‘ Max. 2 marks

    b)Class; l mark

    4 a)Lubrication; Protection; 2 marks

    b)Young people are more active; requiring more energy;/

    Older people are less active; requiring less energy; 2 marks

    5 As the cell gains water by osmosis; the sap/cell vacuole enlarges; pushing the cytoplasm outwards; exerting pressure on the cell wall; Any 3 3 marks

    7 Water molecules cling to each other maintaining a continuous column of water/preventing the break of water column;

    8Water molecules cling to the sides of the xylem vessel walls; l mark

    1(a) – Leaf with serrated margin — go to 2;

    (b) – Leaf with smooth margin — go to –; 2 marks

    9.a)Presence of myelin sheath for insulation/increases transmission; Axon for transmission of impulses;

    Large cell body controls activites of cell; Nerve endings/dendrites receives impulses from receptors cells;

    Node of Ranvier speeds up impulse transmission. b)Inner membrane highly folded/cristae to increase S A for attachment of (respiratory) enzymes.

    4 marks

    10. Cells loosely arranged; to facilitate air circulation;

    Cells have moist surfaces; to dissolve respiratory gases; 2 marks

    11. Can receive blood from any donor/ universal recepient; l mark

    12.a)(i) Arachnida; l mark

    (ii) Spider/scorpion/tick/mite; l mark

    13.Protoctista/protista; l mark

    Autotrophic nutrition; show alternation of generation; Limited movement;

    Limited excretory products/unspecialized respiratory structures; Localised growth; 2 marks

    14 .Alcohol/ethanol; Carbon (IV) oxide; Energy/Adenosine Triphosphate; 3 marks 15 To increase supply of oxygen to the tissues;

    The oxygen is used to oxidize lactic acid (to carbon (IV) oxide, water and energy);

    2 marks

    16 . Protogyny; protandry; Dioecious; Dichogamy;

    Self sterility/incompatibility; Heterostyly;

    Presence of structures/substances to attract agents of pollination; Max. 3 marks 17 .Ovary /Anther; l mark

    18Acrosome/Lysosome contain enzyme to digest membrane of the ovum;

    – Numerous mitochondria to provide energy for movement;

    – Long tail for faster movement; Max. 2 marks

    19Embryo not fully developed;

    – Chemical inhibitors/presence of abscisic acid;

    – Hard/impermeable testa/seed coat;

    – Low horrnones/low enzymes concentration; Max. 3 marks

    20. Genetically acquired beneficial characteristics which occur spontaneously; are perpetuated through reproduction; 2 marks

    21. Continents existed as one large Landmass/Pangea/Laurasian and Gondwana Land;

    Present continents drifted from it leading to isolation of organisms; organisms in each continent evolved along different lines hence emergence of new species; 3 marks

    22. a)Emergence of new life/species/organisms from pre-existing simple forms, gradually over a long period of time, to present complex forms; 1 mark

    b) Thigmotropism/haptotropism; l mark

    Part of the tendril in contact with support causes migration of auxins to the opposite side;

    leading to faster cell division/growth on the side not in contact with the support; This causes the tendril to curl around the support;

    3 marks

    23.Use of biconcave/concave lens/divergent lens; to diverge the rays and make image be focussed on the retina; 2 marks

    24.Contains antibodies that defend the body from foreign antigens;

    – Has white blood cells that produce antibodies/while blood cells engulf antigens;

    – Has platelets that initiate blood clotting to prevent excessive bleeding at an open wound prevent entry of pathogens;

    3 marks

    25. Thin and long to allow for capillarity;

    – Walls lignified to strengthen the stem/to prevent collapse of vessels;

    – Have bordered pits to allow for exchange of materials;

    Max. 2 marks

    26. Genes inherited along with the sex chromosomes; l mark

    Haemophilia; hairy ears/pinna/nose; colour blindness/red green; blue-green colour blindness;

    Muscular diastrophy; baldness

    2 marks

    27 . a)Complete metamorphosis – eggs hatch into larvae while in incomplete metamorphosis hatch

    into nymphs which resemble the adult;

    Complete metamorphosis has four stages; egg, larvae. pupa and adult while an incomplete metamorphosis has three stages; egg, nymph and adult. 2 marks

    b)To allow for growth of the insect; l mark

    28. a)Ligaments; synovial fluid; synovial membrane; articular cartilage;

    synovial capsule; a bone with rounded head fitting into a cavity of another bone;

    Max. 2 marks

    b)(i) Atlas; (ii) Axis allows movement in all planes; 2 marks

    29Form\joints with the legs to make walking possible; l mark

    – Provide large surface area for attachment of muscles; l mark

    – Offers support (to the body weight)

    30Absorption of water; support;

    Opening and closing of stomata;

    Feeding in insectivorous/plants; 2 marks

    Biology Paper 2 (231/2)

    1.a)(i) B -Seta/stalk;

    D- Rhizoid;

    (ii) A- Production of spores/sporulation;

    C -Photosynthesis;

    b)(i) Arthropoda;

    (ii) – Segmented body;

    – Jointed appendages;

    – Presence of exoskeleton

    2 a)E Semi circular canals;

    F Oval window/Fenestra ovalis/Fenestra vestibuli;

    G Cochlea; 3 marks

    b)(i) Lined with hair/secretion of wax/(has glands that secrete wax) to trap foreign bodies;

    Hollow/tubular/tube; to direct sound waves to the ear drum/tympanum/tympanic membrane;

    (max) (2 marks

    (ii) Small/form a lever system/solid; to amplify (sound) vibrations; (2 marks) c) Deafness! absence of pinnal vertigo/tinnitus; (max) (1 mark

    3.a) (i) Provides energy needed to split water molecules into oxygen and hydrogenl photolygis;

    Provides energy for formation of ATP molecules (which is used in dark stage) (1 mark)

    (ii) Combines with hydrogen ions to make glucose; (1 mark)

    (iii) Used to trap light energy; (1 mark)

    b) (i) Starch;

    (ii) Protein; (2 marks)

    c) (i) Lack of vitamin Bl/thiamine; (1 mark)

    (ii) – Stunted growth;

    – Paralysis of legs/arms/limbs/damage to peripheral nerves;

    – Heart failure

    – Swelling of feet/oedema

    – Gastrointestinal disturbances/loss of appetite/sonstipation/diarrhoea/vomiting;

    – Weight loss/muscle wasting

    – Pale skin (2 marks)

    4.(a) Parental phenotypes Smooth Wrinkled


    (b) Parental genotypes

    (i) Genotypic ratio

    (ii) Phenotypic ratio 3 smooth coats 1 wrinkled coat;

    (c) The total number of wrinkled seeds.

    (1 mark)

    1/4 x 14,640 = 3660 ; (2 marks)

    5.a)(i) H – It is long/wide/broad/fiat; to provide a large surface area for attachment of muscles;

    – Has facets; for articulation with sacrum; (2 marks)

    (ii) J Has flexible cartilage; which allows for widening of the (female) pelvic girdle when giving birth/to absorb shock.

    (2 marks)

    b)Allows passage of blood vesselslnervesl and muscles: (1 mark)

    (i) Femur; 1 mark

    (ii) Ball and socket; l mark

    Coccyx; l mark

    See graph on the next page. c) (i) No change in population/population is constant; mice still maturing/have not given birth; (2 marks)

    (ii) Slow/gradual population growth; few mice have reached sexual maturity; (2 marks)

    (iii) Faster/rapid rate of population growth/exponential;

    Many mice sexually matured/reproducing/enough food/space/no competition/ birth rate higher than death/no diseases: (2 marks)

    (iv) Population decline;

    Competition is high / food is limiting / space is limiting/accumulation of toxic waste/disease (outbreak) deathrate higher than birth rate.

    (2 marks)

    6.(i) 6 and 8 ; (l mark)

    (ii) 310 – 115 = 195 mice per month;

    (2 marks)

    Population would increase; (1 marks)

    Food; space ; cage size; water;

    (max) (2 marks)

    7 .a) When a blood vessel is cut/injured platelets/thrombocytes/damaged tissue/wound is exposed to the air; they release thrombokinase/thromboplastin ; an enzyme that activates the conversion of prothrombin; to thrombin; in the presence of calcium ions;

    vitamin Kl phylloquinone ; is needed for the formation of prothrombin;

    Thrombin convens (soluble blood protein) fibrinogen ; into (the fibrous form) fibrin;

    which forms a mesh / network across the wound; The clot so formed prevents excessive bleeding; and entry of disease agents/pathogens/micro-organisms/microbes;

    Max 10 marks

    b)Many to provide a large surface area; across which large amounts of gases diffuse;

    moist surfaces; to dissolve respiratory gases; so as to diffuse. Made of a thin membrane/epithelium/one cell thick wall ; to reduce diffusion distance;

    Highly vascularized; to carry away oxygen; and bring in carbon (IV) oxide; creating a steep diffusion gradients. (10 marks)

    8.Regulation of blood sugar ;
    when blood sugar is below nomtal/90 mg/ 100 cm3 glucagon ;
    triggers the conversion of glycogen to glucose in the liver ;
    the glucose is released into the blood stream.

    When blood sugar is in excess above normal/10 mg/100 cm’, insulin;
    causes the liver to convert glucose excess to glycogen ;
    which is stored.

    Production of heat energy ;
    by increasing the rate of metabolic activities;
    Excretion of bile pigments ;
    produced due to breakdown of wom out red blood cells;
    Deamination/removal of amino group of excess amino acids to form urea; and detoxication/poisonous/toxic substances;

    (Max l0 marks)

    b) Sweat glands excrete urea; excess water;
    and salts;
    hence maintaining salt & water balance in the blood. Evaporation of sweat;
    cools the body due to loss of latent heat of vaporization;
    when the body temperature rises ;
    blood vessels in the skin vasolidate;
    allowing more blood to flow near the skin surface;
    thus heat is lost to the environment byfadiation/convection.

    The erctor pili mucle relaxes hair flattens ;
    in a hot environment reducing insulation;
    hence heat is lost from the body by radiationl convection; to the environment.

    (max 10 marks)

    Biology Paper 3 (231/3)

    1 (i)Sternum; (1 mark)

    (ii)The intemal intercostal muscles relax; pulling the ribs upwards; and outwards;

    This increases the volume of the rib cage while pressure decreases;

    Forcing air into the lungs;

    (5 marks)

    b)(i)Anterior/dorsal view; (1 mark)

    (ii)Name – Neural canal; (1 mark)

    (iii)Function – Passage of the spinal cord. (l mark)

    V: It is thick and solid; for bearing the weight of the body (back) (2 marks)

    S: It is long; to provide a large surface area for attachment of muscles;

    (2 marks)

    (i)image width = 9.8 cm;

    (ii)Magnification = image length / width _

    (iii)Actual lengthl width ‘

    = 9.8:0.| 4.610.] Mg = >< 3 .12 ; Actual length AB – lO.4 1 0.] : 2.13 = 4 83$ cm ; (5 marks)

    3 .

    1 a)Simple leaves …………………………..go to 2;
    b)Compound leaves …………………….. …..go to 4;
    2 a) Leaves net-veined/reticulate …………….go to 3;
    b)Leaves parallel veined …………………….Commelinaceae;
    3 a)Leaves with serrated margins ……………. Malvaceae;
    b)Leaves with smooth (entire) margins…………….Nystaginaceae;
    4 a) Leaves opposite ………………………… .go to 5;
    b)Leaves pinnate ………………………………Bignoniceae;
    5 a)Leaves trifoliate ………………………….Papilionaceae;
    b)Leaves alternate ………………………….. .Compositae;
    ( 10 marks)


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