Download KHWISERO SUB-COUNTY PRE-M-CATS 2015 BIOLOGY 231/2

KHWISERO SUB-COUNTY PRE-M-CATS 2015
BIOLOGY 231/2
MARKING SCHEME
SECTION A
1.
Male
Genotype
X
Female
Bald head
X
YB
X
XX
Normal
X
X
X
YB
X
X
XX
XYB
XYB
2 = /1 = /1
rej 2/4 / ½
2
1
(ii) Boys have Y chromosome which has gene (B) that causes (premature) baldness
(c) Haemophilia; colour blindness; hairy pinina; Duchere muscular dystrophy; ( mark 1st )
(b) (i)
2. (a) Animalia Rej Animal
(b) Centrally located nucleus;
-Absence of cell wall;
-Many small vacuole; ( 1st 2)
(c) On the diagram ( not else where)
A – Golgi bodies/apparatus
B - Cytoplasm
C - Cell/plasma membrane
(d) D – Site for protein synthesis;
E- control activities of the cell
Store genetic materials
3. (a) Phloem tissue;
(b) Q - Sieve pore;
R – cytoplasmic strands/filaments/lamilae;
S – companion cell;
(c) R – translocates food materials in plants/Transports food materials; Acc For translocation- (alone)
(d) Xylem is strengthened with lignin;hence providing support;
e) Active transport/respiration;
4. (a) Villi; Acc Villus
(b) A Epithelial cell/Epithelium
B ;lacteal
(c) Sucrase; Maltase; lactase;
(d) Fatty acids and glycerol; pass into the lacteals by diffusion; inside the lacteal they reassemble/reunite forms fats;
the form in which the are transported; 3 max
(f) – Neutralises acid/HCl comes from stomach;
- Creales alkaline conditions for functioning of pancreatic enzymes;
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- Emulsifies fats increasing their surface are for digestion by lipases
1st role 3 max
5 (a) to expel oxygen: 1mk
(b) To prevent destruction of enzymes by very high temperatures;
(c) To prevent entry of oxygen;(into the mixture so as anaerobic respiration could take place)
(d) it would turn milky/white precipitation;
(e) it is the amount of oxygen required to break down the lactic acid which forms due deficiency of oxygen dug
respiration;
(ii) It ratio obtained when volume of carbon IV oxide produced during respiration is divided by oxygen
produced;
Or
RQ = (volume) of CO2 produced
(volume of) O2 consumed
(f) Carbon IV oxide + calcium hydroxide
Calcium carbonate + water
Reactants Products
6. Compulsory
(a) Sclae;; labeling ;; plotting;; ideality; curve
(b) (i) Blood sugar level increase as a result of the glucose being absorbed in the ileum; by diffusion/active transport;
(ii) The blood level sugar dropped as a result of conversion of glucose to glycogen; ( and fats); by influence of
insulin;
There was also increases rate of respiration; (reducing blood sugar level)
(c) 90mg/100mls of blood;
(d) person B has a defect in the pancreases;
He did not produce enough insulin to control the blood sugar level;
(e) By administration of insulin;
(f) It ensures optimum level of maintained thus maintaining correct osmotic pressure of body fluids;
High levels causes pressure; while low level reduces osmotic pressure form normal.
(g) Glucose is used for respiration; and lost in urine;
7 (a) Distinguish between double and single circulatory system
Double: blood circulates twice in the heart for every complete 200g circulatory of blood, single – it circulates
once;
(b) How the heart is structurally adapted to its structure of adaptation to score
1. Enclosed to pericardium which is tough inelastic double wall that prevent it from over stratching.
Pericardium also secretes pleural fluid which lubricates walls of the heart;
Served with coronary artery; which supply heart muscles with nutrients and oxygen;
Coronary vein; removes metabolic wastes;
The cardiac muscles are myogenic; hence are not fatiqued;
Has pacemaker/SAN; that initiates contraction of the heart muscles
Heart mucles have intercalated discs; which enhance spread of impulses that cause relaxation of contraction of
muscles;
Has four chambers; that ensure double circulation of blood;
Ateries supply blood from body parts as lungs;
2 ventricles has thicker muclses; plitry blood at very high pressure to reach distant parts of the body;
Presence of septum( dividing heart into two equal halves prevent oxygenated blood to mix with deoxygenated blood;
Venacava carry blood into right atrium
Aorta carry blood for heart into rest parts of the body
Semi luna valve prevent flow of blood, arteries leaves from heart to the venclues;
Atrioventricles valve prevent backflow of blood ventricle back into atrum
Valves lendonae: prevent a/v valves from turning inside out ( 18marks)
8. Fossils records/Study/palaentology;
Fossils are remains of ancient organisns preserved in natural occurring materisl for a long period of time. These show
morphological changes of a group of related organisms over long period of time, Nature occurring materials include
the sedimentary rocks : Fossils that have been used include human skull,bnes, teeth etc. Fossils near common
ancenstry army different species of man.
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(b) Geographical distribution.
The theory ofcontinental draft suppose that the present continents originated from one large land mass called
pangea/Laurasian and GOdmana/ and; when the land mass broke up due to drift. Animals with common ancestry
becaome separated/isolated; and underwent different line of evolution;
Illamas of South America and camels of Africa point at common ancestry
Lap tailed monkeys of S.America and Leopard of Africa
The Elephants of Africa and those of Asia
Australia with distinct Marsupials (Kangaroo)
(c) Comparative Anatomy
When comparing from and structures of different organisms, some organs show basic structural similarities which
suggest common ancestry e.g
Homologous structures;
They have similar embryonic/ancestral origin but perform different functions; this si as a result of development
evolution;
Forelimbs of vertebrates, show similar basic pattern hence called pentadactyl limb in bats, it is modifies for flight,
while in manit is for manipulation; Beaks in birds/feet in birds.
Analogous structures; the y have different embryonic origin but are modified to perform similar function eg wing of
birds as those of insects. Thus shows convergent evolution even through are not related.
Vestigial structures; are structures which have become sedimentary/reduced in size hence have became functionless.
This show evolution has indeed taken place.
Coccyx in man appendix in man, wings of flightless kiwi/Emu/Ostrich
Couparative embryology; whenembryo of vertebrate are compared; they show similarities eg pharyngeal slit and
possession of tail; pointing at common ancestry companature serology;
Analysis of blood proteins with refrence to antigen and body reaction of different animals reveal some (phylogenetic)
relationship.
Cell biology; when organelled of cell from different organs is made, it shows some cells have common organelles like
mitochondria choloplatst which suggest common ancestral origin.
Comparative serology
Analysis of blood proteins with reference to antigen –antibody reaction of different animal reveal some phylogenetic
relationship.
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