- 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
Meiosis
(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)
