A group of students set up an experiment to investigate a certain physiological process. The set up was as shown in the diagram below.
A group of students set up an experiment to investigate a certain physiological process. The set up
|Ions||Concentration in pond water||Concentration in cell|
(i) Sodium ions
(ii) Potassium ions
(b) For each processes named in (a) (i) and (ii) above, state one condition necessary for the process to take place.
K.C.S.E Biology Q & A - MODEL 2019PP1QN11
(a) sportsmen release little, concentrated urine at the end of a strenuous exercise
(b) a rabbit has a higher oxygen demand than a camel
(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 2019PP1QN04
(b) Account for the observation made at the end of the experiment.
(c) State the likely identity of G.
(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 2018PP1QN04
(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.
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 2017PP1QN21
- Differences in distribution of chlorophyll/leaf is variegated; green patches would photosynthesize forming starch; giving blue-black colour with iodine solution unlike the regions without chlorophyll;
Explain the physiological process responsible for keeping young seedlings upright.
- Osmosis; water moves into the cells becoming turgid; attaining mechanical support ;
K.C.S.E Biology Q & A - MODEL 2017PP1QN11
(ii) Give two examples of the process named in (a) (i) above in plants.
(b) State two ways by which the movement of dye molecules in the set up would be slowed down.
ii) Gaseous exchange/excretion of carbon (IV) oxide and oxygen;
Translocation of materials;
Absorption/uptake of mineral ions/salts;
b. Lowering the temperature of the medium;
Increasing thickness of the membrane;
Use less dye/add more water/reducing the concentration gradient;
K.C.S.E Biology Q & A - MODEL 2016PP2QN06
(b) When was the rate of reaction 2.6 mg of product per unit time?
(c) Account for the shape of the graph between:
(i) 5°C and 40°C
(ii) 45°C and 60°C
(d) Other than temperature name two ways in which the rate of reaction between 5°C and 40°C could be increased.
(e)(i) Name one digestive enzyme in the human body which works best in acidic condition.
(ii) how is the acidic condition for the enzyme named in (e) (I) above attained’?
(f) The acidic condition in (e) (iii) above is later neutralized.
(i) Where does the neutralization take place?
(ii) Name the substance responsible for the neutralization.
32.5 - 33.5 and 51.0 – 52.0
(c) (i) 5°C and 40° C
As temperature is increased rate of reaction is increased/ more products are formed (per unit time) because enzymes become more active
(ii) 45° C and 60° C
As temperature increase rate of reaction decreases less/products are formed (unit per time) because enzymes become denatured by high temperatures above 40, hence cannot act on substrate.
(d) Increase in enzyme and substance concentration
Use of co-factors and co-enzymes
(e) (i) Pepsin,
(ii) Wall of stomach/ gastric gland/ oxyntic/ pariental/ cell produced Hydrochloric
(f) (i) Duodenum
(ii) Bile juice/ e.g. NaHCO3
K.C.S.E Biology Q & A - MODEL 2016PP2QN05
(b) Suite the significance of the biological process involved in the experiment.
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 2015PP1QN06
(b) State the importance of the physiological process investigated in plants.
(c) Explain the observations made after 30 minutes.
(b) Absorption of water from the soil; opening and closing of stoma; feeding in insectivorous plants; support (in seedlings, leaves,herbaceous plants);
Movement of water from cell to cell in plants.
(c) The thistle funnel gained water by osmosis; because the sucrose solution was hypertonic;
CHARACTERISTICS OF LIVING THINGS
Excretion And Homeostasis
Form 3 Level
Growth And Development
Introduction To Biology
Nutrition In Animals
Nutrition In Plants
Reception_Response And Coordination In Plants And Animals
Reproduction In Animals
Reproduction In Plants And Animals
Response And Co Ordination
Support And Movement In Plants And Animals
Theory Of Inheritance Of Acquired Characteristics
Transplant In Plants
Transport In Plants And Animals