Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2019PP2QN03
In an experiment, students treated seedlings as illustrated below.
​(i) Account for the observations made in seedling I.
(ii) Explain the similarity in the end results made in seedlings II and III. (iii) State the likely treatment that would make seedlings II and III respond like seedling I.
answers
​(i) Positive phototropism/tip bends towards light; light causes migration of auxins (produced at the tip) to the darker sides; (of the shoot) resulting in faster division of cells/ elongation/growth on the darker /opposite side of the shoot hence bending towards light
(ii) both seedlings remain upright; ( erect) seedling II does not have tip while seedling III the tip has been covered by opaque material preventing light causing unequal distribution of auxins; . uniform/even distribution of auxins) (iii) Fitting a gar block treated with auxins at the decapitated end of seedling II; Removing the opaque material covering the tip of seedling III/ replacing the opaque cap with a transparent one;
0 Comments
K.C.S.E Biology Q & A - MODEL 2019PP2QN03
State one importance of irritability to living organisms.
answers
​(a) Enable living organisms to avoid dangerous/harmful/hash climatic environmental conditions; Enable living organisms obtain/access favourable environmental conditions (light, water, oxygen,
K.C.S.E Biology Q & A - MODEL 2019PP2QN02
The table below shows results of blood cell counts per mm3 of blood from a sample of people living at different altitudes.
​(a) Explain the relationship between:
(i) red blood cells count and the altitude; (ii) white blood cells count and the altitude. (b) Explain why chances of nose-bleeding increase with altitude in humans.
answers
(a) i) Number of red blood cells increase with altitude; to increase oxygen carrying capacity (by haemoglobin molecules in blood); since oxygen concentration is lower at higher altitude;
ii) white blood cells serve to protect the body against harmful microorganisms/pathogens; thernadites of pathogen of the body to microbial attack is not dependent on the altitude (to be countered by the white blood cell); hence 6 the number of white blood cell count is constant at whatever altitude; (b) Atmospheric Pressure decreases with the increase in altitude; the imbalance between the (outer) atmospheric pressure at high altitude and the internal blood pressure (generated by the heart) results in (one) nose bleeding at high altitudes/ internal blood pressure is higher than the (outer) atmospheric pressure. K.C.S.E Biology Q & A - MODEL 2019PP2QN01
In an experiment to investigate the effect of sodium chloride on the growth rate in a spinach seedling, seeds were treated with different concentrations of sodium chloride. The results are as recorded in the table below.
​(a) From the results in the table above, explain the effect of increasing the concentration of sodium chloride.
(b) Apart from a ruler, state two other equipment one would need to determine the rate of growth in the roots. (c) With a reason, state one other part of the seedling the students would focus on to determine the effect of sodium chloride on growth. (d) State the likely effect on the seedling of increasing the concentration of sodium chloride to 2.20mol/l
answers
​(a) Increased Nacl concentration/having more Nacl ions decreases water potential/decrease osmotic potential/ increase osmotic pressure/makes water potential more negative outside the seed/seedling in the surrounding solution to be hypertonic to the cell sap in the seedling ; seeds cells take in water by osmosis) are dehydrated/lose water molecules to the surrounding solution , reducing the growth enzyme activity; have reduced growth rates;
(b) Threads(wire/string) Books; Pen; Marker (pen); Dye/water proof ink/ bloating paper/tissue paper (c) Rate of growth/ increase in length of shoot tip/apex it is a region of (active) cell division/growth (d) The seedling will be (dehydrated) /lose water (hence) wither/die/dry K.C.S.E Biology Q & A - MODEL 2019PP1QN25
State one characteristic of muscles responsible for each of the following:
(a) peristaltic movement (b) movement of limbs
answers
​(a) spindle shape
Lack striations/ not striated Uninucleated /one nucleus (b) striated; Numerous mitochondrion; Multinucleated/many nucleus Cylindrical shaped.
K.C.S.E Biology Q & A - MODEL 2019PP1QN24
Explain the evolutionary basis for the ever changing drugs for malaria treatment.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN24
Plasmodium vivax and Plasmodiuin ovale are transmitted by a mosquito. State with a reason whether the two organisms can interbreed.
answers
​(a) they can interbreed; because they belong to the same genus;
They cannot interbreed; because they do not belong to the same species.
K.C.S.E Biology Q & A - MODEL 2019PP1QN23
State three homeostatic roles of the liver.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN22
The chart below illustrates how respiratory gases are transported in the human blood.
​(a) Identify gas Q.
(b) Explain the advantage oxyhaemoglobin has over carboxyhaemoglobin.
answers
(a) carbon(ii) oxide acc. CO
(b) Oxyhaemoglobin is unstable/fully dissociate, releasing oxygen to the tissues/dissociate giving haemoglobin free to take up more gaseous molecules(hence constantly supplying the much needed oxygen to the respiratory tissues); carboxyhaemoglobin is stable/binds itself on the haemoglobin molecules /does not dissociate ,hence starving the tissues/cells of the oxygen ,leading to suffocation/death
K.C.S.E Biology Q & A - MODEL 2019PP1QN21
Make a diagram of a simple, bibbed leaf with a serrated margin.K.C.S.E Biology Q & A - MODEL 2019PP1QN20
State how each of the following features enhance efficient movement of fish in water:
(a) Scale (b) body shape
answers
​(a) faces towards the back/overlap/points backwards to provide a smooth surface for easier movement in water/are stony/ covered with mucus for easier /smooth movement in water/ reduce friction making
(b) streamlined body shape to reduce friction / pointed(stuff) head for easier penetration / passage in water.; K.C.S.E Biology Q & A - MODEL 2019PP1QN19
Below is a diagram of the human digestive system.
​(a) Label with Y on the diagram where enzyme amylase is produced.
(b) Besides the digestive role, explain one other function of the part labelled H.
K.C.S.E Biology Q & A - MODEL 2019PP1QN18
Name the type of tooth in carnivores mainly used for piercing and killing of preys.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN17
Below are photographs of two dogs.
​Explain the possible reason for the difference in the length of their fur.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN16
State two benefits of mutation in living organisms.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN15
State the significance of transpiration to a plant.
answers
(b) enable the plant to get rid of excess water
Creates a suction force /help in the uptake of water /mineral/salts from the soil Maintains turgor in plants/turgidity in cells Cools the plant
K.C.S.E Biology Q & A - MODEL 2019PP1QN14
Name the evidence of organic evolution exhibited by occurrence of similar amino acid molecules in a range of organisms.
answers
(b) comparative physiology/ biochemistry/cell biology;
Acc. Serology /comparative serology.
K.C.S.E Biology Q & A - MODEL 2019PP1QN14
Explain why fossil records as evidence of organic evolution are usually incomplete.
answers
(a) partial/ entire decomposition of dead organisms/ organic matter;
Some parts of or entire dead organisms are eaten by scavengers; Soft bodied organisms do not fertilize; Destruction of parts due to natural disasters, like earthquakes/earth movements like, faulting /folding/ volcanicity/ mass movement; Distortion of parts of an organism due to sedimentary/ faulting/folding/volcanic K.C.S.E Biology Q & A - MODEL 2019PP1QN13
A female human being was found to have an extra sex chromosome in her cells.
​(a) Give the total number of chromosomes in the female individual’s cells.
(b) Explain the possible cause of this condition. (c) State two physical characteristics observed in the female individual with such a condition.
answers
(a) 47
(b)Non-disjunction/failure of homologous chromosome to separate/segregate (in anaphase I) or failure of sister chromosome to separate/segregate (in anaphase II); resulting in an extra X sex chromosome, X chromosome in a cell having XXX instead of XX; (c) infertile / ovary abnormalities; Taller than average female; Development delays; (more pronounced) signs of obesity; Flat feet Abnormally curved fingers; Widely spaced eyes; Abnormally shaped breast bone; K.C.S.E Biology Q & A - MODEL 2019PP1QN12
While investigating a certain metabolic process in plants, students set up the apparatus as shown be low in a classroom and monitored it for 48 hours.
​(a) Identify the metabolic process under investigation.
(b) Account for the observations made in the test tube at the end of the investigation.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN11
Explain each of the following physiological observations:
(a) sportsmen release little, concentrated urine at the end of a strenuous exercise (b) a rabbit has a higher oxygen demand than a camel
answers
​(a) during /after the exercise one sweat ; (profusely to cool the body/eliminate some nitrogenous (wastes) a lot of water is lost through this ; one is dehydrated ;(the little) water that is left in the body system (further) selectively reabsorbed in the kidney tubules (resulting in less but concentrated urine;)
(b) a rabbit has a higher surface area to volume ratio/ smaller in size hence has a bigger surface area exposed to heat loss to the environment/ lose heat faster/ its more active than the camel; hence need more oxygen to(aerobically) respire (to synthesize the needed energy to support its activity /lifestyle; K.C.S.E Biology Q & A - MODEL 2019PP1QN10
In an investigation, students set up the apparatus below in the laboratory and made observations after 72 hours.
​(a) Explain how inclusion of the following components would affect the mouse in the experiment:
(i) light (ii) sodium hydroxide solution (b) State why the students preferred to use a bell jar and not a tin box in the experiment.
answers
​.(a) i) light enables the potted plant to photosynthesize; producing oxygen which is
Inhaled by the mouse, (sustaining it); the illuminated light can further affect /alter some photosynthesized processes in the mouse as a result of constant direct beam of light. (ii) Absorbs carbon(iv)oxide (mainly exhaled by the mouse); while at the same time deny the plant the needed raw material, carbon (iv) oxide to photosynthesize hence suffocating the mouse/ emitting its survival / no oxygen; (b) bell jar is transparent, allow penetration of light for the plant to photosynthesize; tin box is opaque hence does not allow photosynthesis/ could easily heat up altering the temperature inside for the mouse/ plant; K.C.S.E Biology Q & A - MODEL 2019PP1QN09
Below is a photograph of Brassica oleracea, Sukuma wiki leaf.
​(a)State two observable features that adapt the leaf to gaseous exchange.
(b) Explain the relationship between photosynthesis and aerobic respiration within the leaf.
answers
​.(a) broad leaf blade /lamina; that expose more stomata for gaseous exchange; acc broad leaf alone
(b) photosynthesis (within the leaf in the presence of light energy) yield simple carbohydrates /glucose /sugars which form the main substrate during aerobic respiration (producing energy (ATP) During the process of respiration carbon iv oxide produced is intern used as a raw material in photosynthesis; During photosynthesis water is broken down yielding oxygen which is needed/ used in (cellular) (aerobic respiration); K.C.S.E Biology Q & A - MODEL 2019PP1QN08
State the role of each of the following in the mammalian respiratory system:
(a) mucus (b) cartilage rings (c) epiglottis
answers
.(a) trap foreign particles (from the inhaled /entering air); moisten the (inhaled/incoming) air (for efficient gaseous exchange);
(b) keep the wind pipe /trachea open / not to collapse (to allow for continuous flow of air); (c) acts as a valve / flap between the larynx and the oesophagus to permit air to enter the air way to the lungs and food particles to pass into the gut / oesophagus: acc prevent food particles from entering the trachea /air passage during swallowing; |
Archives
December 2024
Categories
All
TOPICSFORM 1
Form 2
Form 3
Form 4
|
We Would Love to Have You Visit Soon! |
Hours24 HR Service
|
Telephone0728 450425
|
|
8-4-4 materialsLevels
Subjects
|
cbc materialsE.C.D.E
Lower Primary
Upper Primary
Lower Secondary
Upper Secondary
|
teacher support
Other Blogs
|