Download westlands form four common evaluation

WESTLANDS FORM FOUR COMMON EVALUATION
Kenya Certificate of Secondly Education BIOLOGY - Paper - 23171 July/August
2013 MARKING SCHEME
1.
2.
3.
-Plasmolysis is a condition when a plant cell loses water
and shrinks / becomes flaccid; while haemolysis occurs
when a red blood cell absorbs water and bursts;
Rej - Animal cell for rbc
- a) Unicellular;
b) Have a closed circulatory system:
Accept 1st one
- use lungs for gaseous exchange;
- Are homoiothermic / endothermic;
-3.) A parasite lives in or on its host organisms to
obtain nutrients without killing it; while a predator
kills its prey and feeds on it to obtain nutrients;
b)- Breaks down organic matter to release nutrients into the
ecosystem / enables nutrients cycling;
Releases carbon (IV) oxide into the atmosphere for use
by plants for photosynthesis;
4.
a) i) - Humerus;
ii) - has head / presence of trochlea / tuberosity;
b) A-Articulates with glenoid cavity of scapula to form ball
and socket joint;
B - articulates with olecranon proces^of ulna to
form a hinge joint;
5„- They are numerous / form a dense network around alveoli
to create a steel concentration gradient for faster
diffusion of gases;
They have moist lining to dissolve gases so that they
can diffuse faster in solution form;
They have thin elastic muscular walls to reduce
distances for faster diffusion of gases;
6.
a) Hand lens;
b) Microscope;
7.
a) Co-enzymes are substances that enhance / promote
activity of enzymes;
b)- They are insoluble in water hence cannot easily be
taken to respiring sites;
- They require a lot of oxygen for complete metabolic
breakdown to release energy;
5.
a) Granum; Rej Grana
b) Carbon (IV) oxide + hydrogen ions -» sugars +
«t ,•«tnr »
9.
a) The biomass is constant; and is independent on
amount of fluids in the organism/ does not decrease due
to loss of fluids.
b) - Pyramid of numbers;
- food chains;
- food web;
10. -Organic matter in sewage is broken down by
decomposers to release nutrients that cause rapid
growth of water plants hence reduce primary
production;
Toxic / poisonous compounds in raw sewage kill
microorganisms in the water; NB: Must mention toxic
compounds in sewage Saprophytic fungi and bacteria in
sewage utilize oxygen in decomposition organic matter
thus decreasing available oxygen hence organisms die
by suffocation;
11. a)Inner membrane is highly folded (Rej:
Highly coiled) to form Cristae that increase surface area
for attachment of respiratory en2ymes; (Rej: cristae are
folded)
has fluid filled matrix that has enzymes that take part in
respiration;
b)- Oxygen concentration; substrate concentration;
surface area to body volume ratio; effect of
hormones that affect respiration
- Thyroxine;
- Adrenaline;
12. a) i) - Telophase I / Telophase of meiosis I;
ii) - Prophase I / Prophase of meiosis I;
b) - Form spindle fibres during cell division;
- Form cilia and flagella used in locomotion in
unicellular organisms;
' 13. a) Rhizobiumsno/Rhizobium leeuminerosum;
b) Symbiosis / symbiotic relationship;
c) Fix nitrogen into the plant;
14. a) Has a large number of Sertoli cells that nourish
developing spermatozoa;
has seminiferous tubules that synthesize spermatozoa;
More sweat
is produced
over the skin surface,
evaporation of
water
in sweat
lowers body
^
close tocoiled
the skin
surface dilate
causing
- Blood
Has a capillaries
long and highly
epididymis
that increase
asurface
biggerarea
volume
of blood
to flow close to the skin
for storage
of spermatozoa;
resulting in loss of body heat by radiation / convection
b) Has
placenta;
which
produces oestrogen and progesterone
across
the body
surface;
hormones
for
maintaining
Hair lies flat over the skinpregnancy;
surface due to relaxation of
erector (pilli) muscle to reduce volume of air over the
15. a) To demonstrate phototropism in plants;
skin surface hence more heat is lost by radiation /
b) In A = The shoot grows and bends- towards the .
convection;
direction or light;
3 ~ Theorganisms
shoot grows
upright ancestry
without to
bending;
19. 1c
-Enables
of common
develop
c) The
aluminium
foil
reflects
light
away
hence
auxins
are
structures that adapt them to different ecological
niches
evenly
distributed
in
ae
shoot
that
results
is
upright
/ occupy different habitatats;
gro'V-h;
20. a)i)
A plumule sheath / coleoptile;
16. a)
growth
in !increase
ii) CPrimary
= root hairs
; rej :results
Hair roots
roots. ±n height /
length of the stem; while secondary growth results in
b) Protects
increase plumule;
in thickness / girth / diameter of the stem;
-
b)
Increased metabolic rate / increased break
down of glucose;
Increased ventilation (breathing) rate; increased heart
beats / increased circulation rate;
22. a)-Causes kidney tuouies to become permeable to
water; hence more water is reabsorbed back into the
bleed stream;
a)- Conduction of nervous impulses;
Plays an important roie in osmoregulation; / ic-ak
balance
23, a) Guard cell;
I b) Conircb opening and closing of stomata;
Has chlorcplasts that absorb sunlight for
photosynthesis;
b) The
juvenile in
hormone
development
larval
21.
a) Located
central promotes
nervous system
/ CNS of
/ Spinal
characteristics
/ inhibits
/ delays
in an
cord;
Acc: In grey
matter of
spinal metamorphosis
cord / brain / CNS.
insect; while moulting hormone (ecdysone) promotes
moulting / metamorphosis / development of larva to
adult form;
c)
18. a) Hypothalamus;
Rej: ABA
24. a) Fungi;
b) i) Fart X - sporangium; ii)
Part Y - Rhizoids;
17. a) Blood group AB and blood group B;
NB: both must be mentioned.
b) The antibodies in anti-B serum reacted with antigen B in
the blood groups; causing agglutination ;
Abscisic acid;
c) Most reproduce asexually while others sexually;
25. a)
i) Genetic engineering refers to identification and
alteration of a gene with desirable characteristics; and
transferring to another organism in order to produce
desirable products;
ii) Co-dominance is a condition in organisms where
both alleles express themselves equally / none is
dorminant or recessive over the other;
b)
Either all offsprings will show dorminant
characteristics;
OR
Half will show dominant while half will show recessive
characteristics;
temperature;
pareafe.il
.
-.r
-| ^
WESTLANDS FORM FOUR COMMON EVALUATION
Kenya Certificate of Secondary Education BIOLOGY - Paper - 231/2 July/August
2013 MARKING SCHEME
La) The gene for foot deforming being dominant; expresses
itself in both homozygous and • heterozygous condition;
girdle is hard to support the upper part of the body; The
illium provide a large surface area for attachment of
thigh muscles that move the legs;
a)- Afferent arteriole wider than efferent arteriole creating
high pressure;
dense network of blood capillaries in the glomerulus
create high pressure (since the lumen of capillaries is
narrow);
high pressure ofblood from the renal artery entering the
glomerulus;
b) It enhances the process of reabsorption of water.
c)
Excess amino acids are deaminated; where the amino
group is reacted with hydrogen to form ammonia;
Ammonia' is toxic and combines with carbon(IV) oxide
to form less toxic urea; urea is then excreted in urine
through the kidney;
4.
a)
Population density;
Population growth;
Population dispersion;
acc first 2
2 deformity : 2 normal
1 deformity : i normal
Use of Punnet square Parental
genotype Dd x dd;
etes^ :; T ......!
^gamete§’-— J! :.l0
|d;
Cr
d
i
d
j Dd
[ Dd
_
| dd;
L
.
| dd; |
b)
1
Grasshopper.
= 12 ; = 4 grasshoppers / m2;
3
Phenotypic ratio
2 deformity : 2 normal;
OR
1 deformity : 1 normal;
b) The individuals are readily selected against by natural
selection;
2.
a) Scapula ; Acc Scapular
b) i) Humerus;
in 600m2 = 600 x 4 = 2400 grasshoppers.
c)
Transect / line transect / belt transect/ capture recapture
(acc the first)
5.
a) X - rods;
Y- cones;
b)
Has pigmented cells / melanin; to absorb stray light thus
preventing internal reflection;
c)
Has photochemical pigment called iodopsin; It’s broken
down (by bright light) into opsin and iodine; causing
depolarization of their surface membrane; generating
an
impulse
ii) Ball and socketjoin;
c)
Area = 30m x 120m = 600m2
Attachment of muscles.
d) Has acetabulum depression / socket (on the side of
ileum); which articulates with the head of femur to form
ball and socket joint at the hip; have a hole obturator
foramen covered by a tough inflexible connective
tissues; to reduce the weight of the pelvic girdle (thereby
reducing the load supported by the hindlimb); the
aperture in obturator foreman allow for passage of blood
vessels and nerves to the legs; pubic symphysis is made
of flexible cartilage, to permit widening of female
girdle during birth; pelvic