KIRINYAGA CENTRAL SUB-COUNTY EFFECTIVE 40 JOINT EXAMS – 2016
231/2 – BIOLOGY PAPER 2 MARKING SCHEME
1.
(a)
(b)
(c)
(d)
(e)
2.
(a)
(b)
(c)
(d)
(e)
A – Epigeal;
(½mk)
B – Hypogeal;
(½mk)
- For anchorage;
- For absorption of water and mineral salts;
(2mks)
A period of minimal metabolic activity in a seed; (OWTTE) (1mk)
- Immature embryo;
- Presence of chemical inhibitors/dormin;
- Impermeable testa.
- Low concentration/absence of hormones/enzymes/auxins/diastase etc;
- Lack of water;
- Lack of oxygen;
Max 2
- It activates enzymes;
- Provides an aqueous medium for enzyme reactions;
- For hydrolysis of stored food;
- For dissolving nutrients;
- For softening the seed coat;
- For osmoregulation/thermoregulation;
Max 2
Anaerobic respiration;
Lactic acid;
- In brewing industry;
- In baking industry;
- In sewage treatment;
- In biogas production;
- In making of silage;
- In production of yoghurt;
- Oxidised to carbon (IV) oxide, water and energy;
- Convertedto glucose in the liver, then to glycogen and stored.
Aerobic respiration
Photosynthesis
(i) Oxygen is used.
- Oxygen is given out;
(ii) Carbon (IV) oxide.
- Carbon (IV) oxide is used up;
(iii) ATP is produced.
- ATP is used up;
(iv) Water is given out,
- Water is used;
(v) Glucose is broken down.
- Glucose is formed;
(vi) Occurs in the mitochondrion. - Occurs in the chloroplast;
(1mk)
(1mk)
Max 2
(2mks)
Max 2
3.
(a)
(b)
(c)
(d)
A – Nitrogen fixation;
D – Absorption;
(2mks)
Nitrites;
(1mk)
Denitrifying bacteria/pseudomonas denitrificans/theobacillus denitrificans/
denitrifiers;
(1mk)
(i)
Leguminous plants/legumes/e.g. beans, peas, covers, cashew nuts,
groundnuts, accassia (accept a correct example).
(1mk)
(ii) Root nodules; rej root Acc. Root tubercles.
(1mk)
(e)
4.
(a)
(b)
(c)
5.
(a)
(2mks)
Root hairs/Roots absorb water by osmosis; cells of the plant become turgid;
leaves become firm/spread out/plants become firm/upright;
(3mks)
(i)
Collenchyma;
(ii) Xylem/tracheids/vessels/sclerenchyma;
(2mks)
The amino group of the amino acid is converted to ammonia; in the liver cells;
ammonia combines with carbon (IV) oxide to form urea;
(2NH3 + CO2  CO (NH2)2 + H2O).
(3mks)
(e)
A: Non-disjunction;
B: Translocation;
C: Inversion;
Down’s syndrome/klinefelter’s syndrome/Turner’s syndrome;
Sickle cell anaemia/Haemophilia;
Radiation; (e.g. x-rays, alpha rays, ultraviolet light, beta rays)
Chemicals; (e.g. colchicines, mustard gas).
Non-disjunction;
(a)
Graph.
(b)
(i)
(b)
(c)
(d)
6.
- Reduction/killing of decomposers;
- Reduction/killing of nitrogen fixing bacteria;
- Destruction of leguminous plants/killing of leguminous plants;
(ii)
- Progesterone
10.5  0.5;
- HCG
48.0  1.0;
2.6  0.5; and 19.4  0.5;
(1mk)
(1mk)
Biology Paper 2MS
2
(3mks)
(1mk)
(1mk)
(2mks)
(1mk)
(1mk)
(1mk)
Kirinyaga Central
0 – 8 weeks – sharp increase; to ensure that corpus luteum does not
disintegrate; to continue producing progesterone/oestrogen hence
prevents degeneration of endometrium;
0 – 20 weeks, a sharp decline; the placenta has started to produce
progesterone and oestrogen to maintain pregnancy;
Max 4
- Causes proliferation of the uterine wall in preparation of implantation;
- Inhibits production of FSH;
- Inhibits contraction of uterus and maintain pregnancy.
- Stimulates growth of mammary glands;
Max 3
Stimulates development of secondary sexual characteristics;
Acc. A specific characteristics e.g. spermatogenesis.
(iii)
(c)
(d)
7.
8.
(a)
Process
Exudation/guttation;
Products
Resins, gums, latex, rubber, calcium oxalate,
salts, water.
(any two) (2mks)
Transpiration/Diffusion; Water, carbon (IV) oxide, oxygen. (any two) (2mks)
Deposition/leaf fall;
Tanins, caffeine, morphine, nicotine, cocaine
(any two) (2mks)
(b)
- Red blood cells/erythrocytes; carry oxygen; to all parts of the body/from
lungs to the tissues;
- Transport carbon (IV) oxide; to the lungs from tissues (award only once
for direction of either carbon (IV) oxide or oxygen).
- Platelets/thrombocytes; produce an enzyme thrombokinase/thromboplastin;
necessary for blood clotting;
- White blood cells/leucocytes/phagocytes;
- Produce antibodies/engulf pathogens; hence provide body defence against
diseases/infections;
- Plasma; transport nutrients; hormones; heat; carbon (IV) oxide; nitrogenous
wastes/urea; mineral ions; fibrinogen/antibodies;
Soil.
Soil particles are surrounded by film of water; the cell sap of the root hair is more
concentrated than soil water; cell membrane of root hair acts as a semipermeable
membrane; Due to concentration difference between cell sap and water in the soil;
water moves into the root hair by osmosis; this reduces concentration of the cell
sap in the root hair; hence water moves into neighbouring cells (by osmosis); this
continues until water reaches the xylem of the root; through cell sap to cell sap;
cytoplasm to cytoplasm; and through intercellular spaces;
Stem.
Once in the xylem water moves up the plant aided by narrowness of the xylem
vessels/capillarity; root pressure; attraction of water molecules to each
other/cohesion; attraction of water molecules to the walls/adhesion; from the
stem xylem water enters the xylem of the leaves;
Leaves.
Once in the leaves water enters the mesophyll; and by osmosis moves from
cell to cell; it reaches the substomatal chamber; where it evaporates into the
air creating transpirational pull;
Biology Paper 2MS
3
Kirinyaga Central
Biology Paper 2MS
4
Kirinyaga Central