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.
answers
(b) Endocrine function/secrets (insulin/ glucagon) hormones; responsible for blood sugar regulation;
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 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 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 2019PP1QN07
Distinguish between chemical and mechanical digestion.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN04
In investigating a certain physiological process, students set up the apparatus as shown below and made the observations after 30 minutes as illustrated.
​(a) Name the physiological process being investigated.
(b) Account for the observation made at the end of the experiment. (c) State the likely identity of G.
answers
. (a) osmosis
(b) solution E is hypertonic/ had more solute molecules compared to solution F; solution F hypotonic to solution E; by osmosis water molecules move through the semi- permeable membrane G (from solution F to E); hence decreases in volume of F/ increased solution E; (c) semi permeable membrane /visking tubing /slice of potato /pawpaw (any other permeable plant tissue) pig bladder/cellophane paper/dialysis membranes. K.C.S.E Biology Q & A - MODEL 2019PP1QN03
The diagram below illustrates a specialised cell obtained from a certain tissue.
​(a) Name the cell.
(b) State two ways in which the cell is structurally adapted to its function.
answers
(a) nerve cell/motor neuron; acc neuron
(b) longer axon to transmit impulses/delivers action potential along way; has numerous dendrites for receiving/delivering /transmitting impulse; myelin sheath for faster transmission of impulse/insulation of axon; Schwan cell for secretion of myelin sheath; node of ranvier to enhance speed of transmission of impulse; cell body has nucleus for controlling nerve impulse transmission.
K.C.S.E Biology Q & A - MODEL 2019PP1QN02
Explain why the bat is classified as a mammal yet it flies.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN02
Besides venation, state two other external characteristics of leaves that can be used to classify plants.
answers
(a) shape of the leaf blade/lamina(broadness or narrowness); leaf margin(smooth or serrated); leaf apex(pinnate dot rounded);leaf arrangement; leaf colour ; (leaf texture(smooth or rough); leaf type(simple or compound)leaf sheath/petiole(absence or presence)
(b) has mammary gland; body covered with fur/hair; gives birth/does not lay eggs; has external ears/pinnae; has seven cervical vertebrae; has sweat glands; heterodonts/four types of teeth K.C.S.E Biology Q & A - MODEL 2019PP1QN01
Name the characteristic of living organisms illustrated by each of the activities described below:
(a) Dressing heavily (b) Bursting of the sporangium in the Rhizopus sp
answers
K.C.S.E Biology Q & A - MODEL 2018PP2QN08
Describe what happens to a meal rich in proteins along the alimentary canal from ingestion to egestion.
answers
​The meal is ingested through the mouth; (In the mouth), it is chewed/masticated (by teeth); to reduce/break it into smaller particles; mixed with saliva (from salivary gland);
The food is then rolled (by the tongue) into boluses; and pushed down into the oesophaghus/swallowed; The boluses move by peristalsis (into the stomach); Constant contractions/relaxations of the stomach walls mix the food, (giving rise to chime); Presence of food in the stomach further stimulates production of gastric juice; which contains pepsinogen; and rennin/chymosin; Pepsinogen is activated to pepsin; by hydrochloric acid; (contained in the gastric juice). Pepsin breaks down proteins to peptides; Rennin converts/coagulates the protein, caseinogen; in milk to casein; (which is abundant in young children). It is then pushed into the duodenum (through the pyloric sphincter); Pancreatic juice in the duodenum contains trypsin; which digests proteins into peptides; (secreted in an inactive form, trypsinogen) In the ileum, intestinal juice/Succus enfericus is secreted; It contains peptidase enzymes; which breaks down polypeptides into amino acids; It also contains polypeptidase enzyme; which breaks down peptides to amino acids,completing the process of digestion of the proteins; The amino acids are absorbed into the bloodstream/pass through the epithelia of the villi, and the capillary walls into the blood-stream; by active transport; The undigested/indigestible proteins/food substances pass through to the colon/large intestines; where water is absorbed; leaving a semi-solid waste material being passed on to the rectum; then out through the anus (as faeces); K.C.S.E Biology Q & A - MODEL 2018PP2QN05
The photograph below represents a plant in a Certain Division
​(a) (i) Name the Division to which the plant belongs.
(ii) With reference to the Photograph, state three observable features of the Division named in a(i) above. (b) Name the part labelled N and P. N P (c) Explain how the part labelled Q is adapted to its function
answers
​a) i. Bryophyta;
ii. Has capsules (for enclosing spores); Has (long) setae (for supporting the capsules/for effective propagation of spores); (Developed) rhizoids (for anchorage/absorption of water/mineral salts); Thalloid in nature/Thallus/undifferentiated; b) N — Capsule; P—Seta; (c)Numerous/hair-like to increase the surface area for absorption;/to enhance rate of absorption of water/nutrients/dissolved mineral salts; Numerous/hair-like to hold firmly on the surface/not to be easily blown away/displaced/anchorage; K.C.S.E Biology Q & A - MODEL 2018PP1QN06
The diagram below illustrates tissue fluid and cells surrounding a capillary.
​(i)Name fluid G.
(ii) Give two ways by which fluid G is different from tissue fluid.
answers
(i) (Blood) plasma;
(ii) Has (more large) proteins/blood platelets; High (hydrostatic) pressure/low pressure of tissue fluid; Has red blood cells; K.C.S.E Biology Q & A - MODEL 2018PP1QN04
A group of form two students placed a fresh leaf in warm water. They observed that air bubbles formed on the surface of the leaf.
(a) What biological process were they investigating? (b) Name the structures from which the air bubbles were coming from. (c) Explain the distribution of the structures named in (b) above on the leaf surfaces of a land plant.
answers
​a) Photosynthesis;/gaseous exchange in plants;
b) Stoma/somata; c) Are more on the lower surface of terrestrial plants/fewer on the upper surface; to reduce transpiration;
K.C.S.E Biology Q & A - MODEL 2018PP1QN03
Which sets of teeth would be used in chewing sugarcane for maximum extraction of sap?
answers
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