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
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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;
K.C.S.E Biology Q & A - MODEL 2019PP1QN07
Distinguish between chemical and mechanical digestion.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN06
​(a) Name the respiratory structure in the amoeba.
(b) Give a reason for your answer in (a) above.
answers
(a) cell membrane/plasma membrane /plasmalemma;
(b) has a large surface area to volume ratio
K.C.S.E Biology Q & A - MODEL 2019PP1QN05
Explain why significantly increasing the blood pH slows down the rate of selective reabsorption of materials in the kidney tubules.
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
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