KNEC KCSE Biology Paper 2 Question Paper / 2015 KCSE Tharaka South Joint Examination

a). Pedigree
b). Grand mothers; and by mututation
c). i) Grand parents XHY, XHXh
ii). The two couples Xh
Yh
; Xh
Y;Xh
Y, Xh
XH
iii). Xh
Y/Xh
Xh
/Xh
Y
iv). Bleed profusely for long period even from the slightest cut, inject with vitamin K to cause blood clotting which
seals up the would
v). Inject with vitamin K to cause v=blood clotting which seals up the would

a). X – anther / male part
Y – style / pistil / female part
b). Epigyneous / superior flower / ovary above the other floral parts
c). i). Wind pollinated flower
ii). Anther located above the stigma
rej. Brightly coloured petals / scented nectarines
d). X /W
e). 30 chromosomes
f). Anthers located below the stigma self sterility / incompatibity Protandry / male parts (stamen) maturing earlier than the
female parts (pistill) Protagyny / female parts (pistil) maturing earlier that the male parts stamens any one stated correctly
1 mk

a). Hawk and water snail 2mk
b). decrease in phytoplankton 1mk
increase in population of small fish
c). Hawk, top predator, amount of energy decrease in successive trophic levels / energy is lost through respiration
Undigested / uncovered food (mark any reason 1 x 1 = 1mk )
d). i) Cause decomposition / recycling of nutrients 1mk
ii). Root nodules have bacterial / rhizobium sp to convert free nitrogen into nitrates in the soil 1mk
e). Capture – recapture or capture release recapture 1mk

a). Ball and socket joint 1mk
b). Z – femur
U – articular cartilage 2 mks
c). Shoulder / pectoral girdle, hip/pelvic
girdle
rej – (pector / pelvic alone)
d). – Reduction of friction / lubrication
Absorption of shock / distribution of pressure 2mks
e). Smooth muscles 1mk

a) A – Afferent arteriole
N – Proximal convoluted tubule 2 mks
b). Bowman’s capsule, proximnal convoluted tubule, distal convoluted tubule 1mk
all named or none
c). Loop of Henle
d). Antidiuretic hormone / vasopresin
e) i). Cell lining tubule have numerous mitochondria which provide energy for reabsorption
iii). Tubule long / highly coiled to increase surface area
iv). Coiling of tubule reduce speed of flow of filtrate to allow more time for efficient reabsorption
v). Tubule is well supplied with blood capillaries for efficient transport / reabsorption any correct first two

a) Title 1mk
Labelled axes 1mk
Correctly used scale 2mk
Plotting of points (Any 3 corredtly plotted points in each case 1mk each 1 x 2 = 2mk)
Labeling of curves 1mk each 2mk
b). Carbohydrates formed during photosynthesis
0+0+5+30+60+30+5+0+0= 130mg ½ mk
Carbohydrates used during respiration
10+10+10+10+10+10+10+10+10+10= 90mg ½ mk
c). 6:36a.m + 10 minutes 1mk
5:24p.m + 10 minutes 1mk
d). i) No carbohydrates 1mk

ii). Gradual increase in carbohydrates 1mk
fromed due to increasing light internsity 1mk
e). Reduced light available, hence carbohydrates formed becomes low 1mk
f). Carbon (IV) oxide 1mk
moisture / water 1mk
g). Starch ½ mk
Glycogen ½ mk

a). Secondary thickening id facilated by meristamatic cells known as cambium which are located between phloem and xylem in
vascular budles of plants the cambium divides radically to form a rine (cylinder) of cambium rissue with the xylem inside the
ring and the phloem outside the ring, cells of the cambium ring divide to four secondary phloem outside intervascular
cambium (between vascular bundles) divide to form secondary phloem outside. Intervascular cambium (between vascular
bumdles) divided to form secondary parenchyma, thereby increasing the growth of meducary easy much more xylem is
formed than phyloem thus pushing phlem and cambium outwards the rate of secondary growth is dependant on the season /
rainy resulting in annualar rings,. Cork. Camvium / phellogen divides to form new cork / bark rissue to accommodate
increased growth on outside and secondary cortex on the inside. 14mks
b). Choose / identify a yound leaf which is folded, use the same leaf throughout measure the total length of the whole leaf (acc.
Measure of any part of the leaf / record / length) repeat the procedure at regular interval, until no change occurs in length /
until it gets constant length the average rate of growth is equal to toatal increase in length divided by the period taken to
achieve final length

a). Organic evolution is a gradual change of living organism from simple life forms to more complex forms, over a long period of time
b). Homologous structures are structures of the same embroyonic origin that become modified in the course of evalution to perform different ecological niches Analogous structures are structures of different embryonic origin that become modified in the course of evolution to perform similar functions in the same ecological niches. 2 mks
c). How natural selection brings about adaoptation id the species ro its environment
− organisims in the same environment are always competing for resources such as food mates, shelter etc as well as enduring the harshness of the environment.
− This phenomenon is described as a struggle for existence
− those organisms that best adapted to survive to productive maturity and give tise tooffrsprings of the next generation.
− the less well adapted die yound, hence survival of the fittest
− if the favourable charaxteristics possessed by the ‘fittest’ organisms are genetic they are passed onto the offspring
− this leads to a natural occurrence of variation onto the offsprings
− this leads to a natural occurrence of various without a species
− if these variations are genetic change in the characteristics of the species making it better adapted to its environment
− accumulation of small variations over a long period of time lead to the emergence of new dorms of life i.e ne species
− if suited and well adpted to the new environment these new forms reproduce successfully and pass on their characteristics
− if not suited these new forms are eliminated by nature leaving mutant forms which are better adapted to the environment
− through this process nature selects those oragnisns with better adaptations while ensuring the elimination of those not able to adapt to the changing environment.
− thus the changing eniviroment (nature) forces and organism (a species ) to adapt or otherwise be eliminated
Total 18
Max 16​