K.C.S.E Biology Q & A - MODEL 2017PP2QN01
The diagram below represents a nucleus.
(a) Name the structures labelled E and F.
(i) E F (ii) State the function of F. (iii) With reference to the nucleus, state one difference between an animal and a bacterial cell. (b) Name the plant cell organelle: (i) that stores chlorophyll (ii) responsible for intracellular digestion. (c) State two main functions of the vacuole in the amoeba.
ANSWERS
(a) E—Nucleolus;
F — Nuclear pore/nucleopore; ii. Facilitates movement of materials in and out of the nucleus; iii. Nuclear material in the bacterial cell is not enclosed within a membrane /prokaryotic, while in animal cell it is enclosed eukaryotic; (b) i. Chloroplast; ii. Lysosome; (c) i. Feeding (food vacuole); ii. Osmoregulation (contractile vacuole); iii. Excretion/removal of wastes;
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K.C.S.E Biology Q & A - MODEL 2016PP2QN05
A freshly obtained dandelion stem measuring 5cm long was split lengthwise to obtain two similar pieces. The pieces were placed in two different solutions of different concentrations in petri dishes (L1 and L2) for 20 minutes. The appearance after 20 minutes is as shown.
(a) Account for the appearance of the pieces in solutions L1 and L2
(b) Suite the significance of the biological process involved in the experiment.
answers
(a) L1 - Inner cells gained water by Osmosis; hence increased in length; epidermal cells did not gain water because they are covered by a water proof cuticle leading to curvature.
L2 - Inner cells lost water by osmosis; leading to (flaccidity) decrease in length; epidermal cells did not lose water due to waterproof leading to curvature (b) Absorption of water by the roots Opening and closing of the stomata K.C.S.E Biology Q & A - MODEL 2016PP2QN04
The diagram below represents some gaseous exchange structures in humans.
(a)Name the structures labeled K, L and M.
(b) How is the structure labeled J suited to its function? (c) Name the process by which inhaled air moves from the structure labeled L into blood capillaries. (d) Give the scientific name of the organism that causes tuberculosis in humans.
ANSWERS
(a) K- Pleural membranes
L- Alveolus M- Intercostal muscles (b) Has C- shaped cartilage rings that support it preventing it from collapsing and allow free flow of air Inner lining has mucus secreting cells that trap fine dust particles and microorganisms Inner lining has hair like structures called cilia that enhance upward movement of the mucus to the larynx (c) Diffusion (d) Mycobacterium tuberculosis (underline separately). K.C.S.E Biology Q & A - MODEL 2016PP2QN03
The diagram below represents bones at a joint found in the hind limb of a mammal.
(a) Name the bones labeled X, Y and Z
X Y Z (b) (i) Name the substance fi)und in the place labeled W. (ii) State the function of the substance named in (b) (î) above. (c) Name the structure that joins hones together at the joint. (d) State the difference between ball and socket joint and the one illustrated in the diagram above. (e) Name the structure at the elbow that performs the same function as the patella.
ANSWERS
(a) X- Femur
Y- Tibia Z- Fibula (b) (i) Synovial fluid (ii) Lubrication of the joint/ shock absorption Distribution of pressure (c) Ligament (d) Ball and socket joint allows movement in all planes while the illustrated allows movement in one plane only. Accept 360 for all planes 180 for one plane (e) Olecranon process
K.C.S.E Biology Q & A - MODEL 2016PP2QN02
Explain why people with sickle cell trait have an adaption survival advantage over normal individuals in malaria endemic regions.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2016PP2QN02
Differentiate between sickle cell anaemia and sickle cell trait.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2016PP2QN02
How is sex determined in man?
ANSWERS
K.C.S.E Biology Q & A - MODEL 2016PP2QN01
The diagram below represents a human foetus in a uterus.
(a) Name the part labeled S.
(b) (i) Name the types of blood vessels found in the structure labaled Q. (ii) State the difference in composition of blood found in the vessels named in (b) (i) above. c)Name two features that enable the structure labeled P to carry out its function. (d) State the role of the part labeled R.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2015PP2QN05
In an experiment to investigate a plant response, the set up shown in the diagram below was used.
(a) Name the type of response that was being investigated.
(b) If the Klinostat was not rotating: (i) state the observations that would be made on the seedlings after three days; (ii) explain the observations in (b) (i) above. (c) If the experiment was repeated with the Klinostat rotating: (i) state the observation that was made on the seedlings after three days; (ii) give a reason for the observation made on the seedlings.
ANSWERS
(a) Geotropism/Gravitropism;
(b) (i) The shoot tip/plumule curved upwards; root tip/radicle curved downwards; (ii) Auxins migrated downwards to lower side; Higher concentration on the lower side; caused more growth on the lower side than on the upper side in shoots inhibited growth on the lower side than on the upper side in the roots; (c) (i) The seedling will continue growing horizontally; (ii) There was even distribution of auxins (on the tips); K.C.S.E Biology Q & A - MODEL 2015PP2QN04
In an experiment to investigate a factor affecting photosynthesis, a potted plant which had been kept in the dark overnight was treated as shown in the diagram below and exposed to light.
(a) Why was the potted plant kept in the dark overnight’?
(b) Which factor was being investigated in the experiment? (c) (i) Which test did the students perform to confirm photosynthesis in the leaves labelled P and Q? (ii) State the results obtained in the leaves labelled P and Q. P Q (iii) Explain the results obtained in the leaves labelled P and Q. P Q (d) What was the purpose of leaf Q in the experiment?
ANSWERS
(a) To destarch/remove starch from the leaves;
(b) Carbon (IV) Oxide/CO2; (c) (i) Test for starch; (ii) p - Retained the colour of iodine solution/brown/yellow; Q - Turned blue-black/black/dark-blue; (iii) P - Did not photosynthesize /no starch is formed because Sodium Hydroxide pellets absorbed Carbon (IV) Oxide; Q - Photosynthesized /starch was formed because Carbon (IV) Oxide was in the flask; (d) Control (experiment);
K.C.S.E Biology Q & A - MODEL 2015PP2QN03
A female with sickle cell trait marries a normal man. The allele for sickle cell is HbS and the normal allele is HbA. Determine the probability that their first born will have the sickle cell trait. Show your working..
K.C.S.E Biology Q & A - MODEL 2015PP2QN03
State two examples of discontinuous variation.
ANSWERS
(i) Sex;
(ii) ABO blood group system/Rhesus factor; (iii) Ability to roll tongue; (iv) Free or attached earlobe; (v) Presence/ absence of hair in the nose! on the ear pinna; (vi) Finger prints; ability to taste PTC (phenythiocarbamide) PTV (phenylthio urea) (vii) Winglength in prosophila; (viii) Size of abdomen in drosophila; (ix) Eye colour in prosophila; (x) Smooth/wrinkled seed coats in pea plants; (xi) Green/yellow seed coats/seed coat colour in pea plants; (xii) Polymorphism/melanic and non melanic forms in moths.
K.C.S.E Biology Q & A - MODEL 2015PP2QN03
What is meant by the term genetics?
ANSWER
K.C.S.E Biology Q & A - MODEL 2015PP2QN02
The diagram below illustrates the structure of the female part of a flower.
(a) Name the part labelled W.
(b) Describe what happens when the pollen tube enters the structure labelled V. (c) What do the structures labelled R and T develop into after fertilization? R T
ANSWERS
(a) W - ovary wall/ovary;
(b) Tip of pollen tube bursts open; one of the nuclei fuses with the egg cell nucleus; to form a diploid zygote; while the remaining male nucleus fuses with the polar nuclei; to form a triploid endosperm nucleus; (c) R - Endosperm/primary endosperm; T - testa/seed coat; K.C.S.E Biology Q & A - MODEL 2015PP2QN01
The diagram below illustrates a blood capillary surrounding a structure for gaseous exchange in human beings.
(a) Name the gaseous exchange structure.
(b) Identify the gases labelled Y and Z. Y Z (c) How does the gas labelled Y reach the inside of the blood capillary? (d) How does cigarette smoking lead to lung cancer?
ANSWERS
.(a) Alveolus;
(b) Y - oxygen/O2; Z - Carbon (IV) Oxide/CO2; (c) Oxygen concentration is lower in the blood capillary than in the alveolus; oxygen diffuses; through the epithelium and endothelium of capillary wall, plasma into the red blood cells where it combines with haemoglobin. (d) Cigarettes/tobacco contains tar; tar contains carcinogenic substances; which trigger cancer K.C.S.E Biology Q & A - MODEL 2014PP2QN05
The diagram below represents the transverse section of the spinal cord.
(a) Name the part labelled H.
(b) State two functions of the fluid found in the part labelled J. (c) Give a reason for the colour of white matter. (d) Name and give the function of the enzyme found at the part labelled K. Name Function (e) On the diagram, use an arrow to show the direction of impulse transmission along the neurone labelled 1.
answers
(a) H - cell body;
(b) Has nutrients for nourishment of neurons, brain, spinal cord; Acts as a shock absorber for protection of spinal cord from mechanical damage; (c) Contains myelin sheaths (of neurons which are made up of fats that make it have a shiny white appearance); (d) Cholinesterase: Breaks down Acetyicholine; to acetic acid and choline; (e) Correct arrow on neurone 1 points towards the grey matter;
K.C.S.E Biology Q & A - MODEL 2014PP2QN04
Explain why people with sickle cell trait have an adaptive survival advantage over normal individuals in malaria endemic regions.
answers
K.C.S.E Biology Q & A - MODEL 2014PP2QN04
Differentiate between sickle cell anaemia and sickle cell trait.
answers
K.C.S.E Biology Q & A - MODEL 2014PP2QN04
How is sex determined in man?
answers
K.C.S.E Biology Q & A - MODEL 2014PP2QN03
(a) Describe the mechanism of gaseous exchange in plants through the lenticels.
(b) Explain each of the following: (i) the tracheoles lack spiral bands of chitin; (ii) the floor of the mouth is lowered during inhalation in a bony fish.
answers
(a) O2, concentration is higher outside than inside the lenticels; O2, diffuses into lenticels; then into the cells; CO2 concentration is higher inside the lenticels than on the outside CO2 diffuses out of the lenticels into the atmosphere;
(b) (i) To provide a large surface area! make them thin; for gaseous exchange to reduce diffussion distance for respiratory gases; (ii) This increases the volume of the buccal cavity while decreasing the pressure; which forces water to rush into the mouth; K.C.S.E Biology Q & A - MODEL 2014PP2QN02
The diagram below illustrates the role played by red blood cells in the transportation of carbon (1V) oxide.
(a) Other than the carbon (IV) oxide transportation in the red blood cells, name the other form of carbon (1V) oxide transportation in humans.
(b) (i) Name substance F (ii) Name the enzyme marked C and state its role in the reaction. Enzyme Role (c) Explain why transportation of carbon (1V) oxide in red blood cells is advantageous. (d) Explain the role of calcium ions in blood clotting.
ANSWERS
(a) Carbonic acid/carbaminohaemoglobin/hydrogen carbonate;
(b) (i) Water; (ii) Carbonic acid; Role: catalyses reaction between carbon IV oxide and water to form (weak) carbonic acid; (c) Prevents accumulation of acidity/maintains pH of blood since hydrogen ions combine with haemoglobin to form Haemoglobin acids; Faster; due to the catalytic effect of carbonic anhydrase; (d) Activates thromboplastin; thrombokinase to neutralize heparin/convert prothrombin to thrombin; K.C.S.E Biology Q & A - MODEL 2014PP2QN01
(a) State four characteristics of fruits dispersed by animals.
(b) State two roles of each of the following hormones in menstruation: (i) luteinising hormone; (ii) oestrogen.
ANSWERS
(a)
K.C.S.E Biology Q & A - MODEL 2013PP2QN05
The diagram below represents a mammalian pelvic girdle.
(a) How are the structures labelled H and J adapted to their function?
(i) H (ii) J (b) State the function of obturator foramen. (c) (i) Name the bone that articulates with the pelvic girdle at acetabulum. (ii) Name the type of joint formed by the acetabulum and the bone named in (c)(i) above. (d) Name the bone formed by the fusion of caudal vertebrae inhuman beings.
answers
K.C.S.E Biology Q & A - MODEL 2013PP2QN04
In an investigation, a variety of pea plants grown from seeds with smooth coats were crossed with plants grown from seeds with wrinkled coats. All the seeds obtained in the first filial (F1) generation had smooth seed coats.
(a) Using the letter R to represent the gene for smooth seed coat, work out the genotype of the F1 generation. Show your working.
(b) If the F1 generation was sel fed, determine the phenotypic ratio of the second filial (F,) generation. Show your working. (c) If the total number of seeds in the F, generation was 14 640, calculate the number of seeds with wrinkled coats. Show your working. K.C.S.E Biology Q & A - MODEL 2013PP2QN03
(a) Explain the importance of the following in photosynthesis:
(i) light; (ii) carbon(IV) oxide; (iii) chlorophyll.
(b) Name one appropriate food substance for each of the following enzymes:
(i) ptyalin (ii) pepsin (c) State the cause and two symptoms of Ben-ben. Cause Symptoms
answers
(a) (i) Provides energy needed to split water molecules into oxygen and hydrogen/photolysis;
Provides energy for formation of ATP molecules (which is used in dark stage) (ii) Combines with hydrogen ions to make glucose; (iii) Used to trap light energy; (b) (i) Starch; (ii) Protein; (c) (i) Lack of vitamin B1/thiamine; (ii) . Stunted growth; Paralysis of legs/arms/limbs/damage to peripheral nerves; Heart failure Swelling of feet/oedema Gastrointestinal disturbances/loss of appetite/constipation/diarrhoea/vomiting; Weight loss/muscle wasting Pale skin |
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