Download EKSIKA -2016 BIOLOGY PAPER 2 (THEORY) 231/2 MARKING

EKSIKA -2016
BIOLOGY PAPER 2 (THEORY)
231/2
MARKING SCHEME
Rej Capital letters
Rej commars
Check correct ordericpmm
Lined dividing upper and lower jaw Must be clearly shown
1.a) (i) 2 C 1
2
1
pm
2
2
m;
(ii) Upper jaw 8
Lower jaw 8
total 16×2 =32
3
3
b) Salivary smylase/ptyalin;
c)
X
Y
Canines;
Molar;
Pointed for tearing flesh rej chisel shaped
Have cusps and ridges/wide surface for crushing/chewing (food); ref strong
d)Periodontis/periodontal disease/ginginitis/pyorrhoes
Acc. Periodontal
-
Dental carries;
Hormone
8
Source
2.a)
Glucagon;
Pancreas;
Pituitary gland;
Function
Stimulate absorption and re absorption of
salts Na+ into blood
Stimulate reabsorption of water back into
bloodstream;
b) All Glucose is reabsorbed back into bloodstream along kidney nephorome under influence of
insulin hormone;
c) to reduce the surface area for transpiration;
to conserve water in the plant;
to eliminate accumulated wastes on leaves
(8mks)
3. a(i) M-Glycolysis;
N- krebs cycle/tric acid cycle/ incarboxylic 8acid cycle;
ii) pyruric acid;
b)M- cytoplasm;
N- Mitochondria / matrix of mitochondria;
c) RQ = CO2 Produced =56;=0.7;
O2Consumed =80
d) Ethanol/ethylacohol;
8mks
4. a) X- blood platelets/thrombocytes;
Y- white blood cells/lencocytes;
b) X-involved in blood clotting;
Y- Protection against pathogens/disease causing organisms; A.C. correct examples rej germs
c) Biconcave shaped to increase surface area for diffusion of oxygen/gases;
Numerous for efficient transportation of gases;
d) magnification
=
actual length =
image length = 40mm;
magnification 50000
(1mm=1000micrometers)
40 ×1000
image length =
actual length
um = 8um
8
5000
5. A) a- corolla/petal;
D- Ovule;
mark on diagram. reject sees
b)
B
Stigma)
C
Anther
Insect pollicated
Small/ sticky stigma
Rej shor
Short/small anthers (which are firmly
attached to filatement
Wind pollinated
Long/feathery stigma;
Long/large anthers (which are
loosely attached to filatement ;
c) Integument develops into
seed coat/testa
Zygote
embryo
Triploid nucleus
endosperm
Ovary wall
pericarp
Ovary
fruit
Ovules
seeds
Corolla/petals/style/sepals/spemens/filament/dry only fall off/withers (MARK 1ST 2)
d) Division ; spermatophyte;
class : Dicotyledonae;
8
SECTION B
6.a) 11 Hours; and 31 Hours; Acc. 30hours
b) (i) A and B
The number of bacteraial dividing are few;
Bacteria are adjusting to hew environment;
Hence low increase in population
(ii) B and C
More cells ae fivding; due suitable environment/adjusted to new environment/fanurable
conditions; few dying; therefore high increase in population;
(iii) C and D
No population change; number produced is equal to number dying; (acc- number for pop and
many for more)
c) accumulation of toxic wastes; that kills bacterial; depletion of nutrients; leading to death;
overcrowding ; leading to competition for space/food;
mark 4 award death of
bacteria once
d) (i) The population will remain the same;
(ii) Temperature not conducive for division;
rej(ii) if (i) is wrong
e) For food to be sufficient/adequate;
for social amenities/Education/clensing/ employment to be adequate;
for health services to be adequate;
land space is not increasing/ to avoid overexploitation of land;
reduced crime rate; acc. Prostitution as crime rej. Reduced immorality
any first 3
7. (a) Searching for food/water/ shelter;
 Migration away from unfavourable places/natural disasters/catastrophies, fire, floods;
 Escape from predators/enemies;
 Dispersion/colonization of new areas;
4mks
b) – the vertebral column consists of a series of vertebra held together loosely so that it is
flexible;
 myotomes/muscles; associated with vertebral column produces movement;
 the sideways and backwards thrust of the tail and body against water; results in resistance
of the water pushing the fish sideways and forward in a direction opposed to thrust;
 head not flexible; so as to maintain the forward thrust
 body streamlined; to reduce resistance (so swim smoothly);
 presence of fins; help in propulsion/balance; paired fins (pectoral and pelvic); for
controlling pitch and string dams movement; unpaired fins (divsal, ventral, anal); for
preventing yawing and rolling
 presence of swim bladder; make fish buoyant
 scale overlap forward the back; provide smooth surface/reduce water resistance; 16mks
8. Gaseous exchange in terrestrial plants
Gaseous exchange takes place in spongy mesophyll;
During the day air diffuses into large air spaces of spongy mesophyll; through stomata;
The carbon(iv) oxide in the air diffuses into photosynthetic cells; in solution form;. During
photosynthesis carbon (iv) oxide is used; while oxygen is produced; some of the oxygen is used
in respiration; while the rest/some of the oxygen diffuses out of the leaf; through stomata.
During night, air diffuses into air spaces of spongy mesophyll; the air dissolves into film of
moisture;
The oxygen in the air diffuses into cells; and is used in respiration; during which carbon (iv)
oxide is produced; the carbon (iv)oxide diffuses out of the leaf; through stomata due to
concentration/diffusion gradient; At night carbon(iv)oxide accumulates in the leaf since
photosynthesis does not take place;
Some gaseous exchange also takes place through cuticles ; gaseous exchange occurs through
epidermis of young leaves and stems;
Epidermis of the root carries net gaseous exchange with air int the soil some plants have
breathing roots through which gaseous exchange occurs; ACC.pheumatophurnves
Gaseous exchange occurs through lenticles (found in older stems); The cork cells at a lenticels
are intensely produced; Gaseous exchange takes place between cork and atmosphere within
the loosely packed cell;
25mks