Gaseous Exchange Questions and Answers1. 1992 Q11 P1 The diagram below represents an organ from a bony fish. Study the diagram and answer the questions that follow (a) Identify the organ and the parts labelled M, N, and P
M________________ N________________ P________________ (b) How the structures are labelled P adapted to their function? 2. 1994 Q14 P1 What are the characteristics do gills of a fish and the mouth cavity of a frog have in common that enables them to be efficient in gaseous exchange? 3. 1996 Q14 P1 (a) Describe the path taken by carbon dioxide released from the tissue of an insect to the atmosphere (3 marks) (b) Name two structures used for gaseous exchange in plants (2 marks) 4. 1998 Q4 P1 Why are gills in fish highly vascularised? 5. 1999 Q5 P1 Suggest three reasons why green plants are included in a fish aquarium. 6. 1999 Q16 P1 Describe the: a) Process of inhalation in mammals. b) Mechanisms of opening and closing of stomata in plants. 7. 2000 Q11c P1 State two ways in which the leaf is suited to gaseous exchange 8. 2001 Q10 P1 Name three sites where gaseous exchange takes place in terrestrial plants. 9. 2002 Q9 P1 Name two gaseous exchange structures in higher plants. 10. 2003 Q13 P1 The diagram below shows gaseous exchange in tissues.
a) Name the gas that diffuses: i) To the body cells ii) From the body cells b) Which compound dissociates to release the gas named in (a) (i) above? c) i) What is tissue fluid? ii) What is the importance of tissue fluid? K.C.S.E Biology Q & A - MODEL 2019PP2QN08
Explain the effect of increased physical activity on the following organ systems:
(a) heart (b) lungs (c) kidneys (d) skin. 
answers
​(a) Heart
-Increased heart beat/ rate/cardiac frequency; increase blood pressure; pumping more blood to the muscles/Peripheral blood vessels; at a faster rates; supplying oxygen; Nutrients; for continued oxidation/respiration; to yield energy needed to sustain the (vigorous) contraction/relaxation of muscles during the physical activity; carbon (iv) oxide /Lactic acid/other Nitrogenous wastes/Metabolic wastes produced during the process are also eliminated/ transported to the relevant excretory organs for elimination; the wastes ,if left to accumulate Can also intoxicate/poison cells/cause muscle cramps/pain/fatigue; (b) Lungs -Panting /increased breathing rates; cause the lungs to expand/increase in volume to take in more air/oxygen; and deflate to expel more carbon (iv) oxide; more oxygen is taken in (during exercise) to sustain the process of muscle respiration/to produce the required energy (for constant muscle contraction and relaxation);
Kidneys also maintain the blood plasma pH; and osmotic balance; by elimination excess hydrogen ions(H+) that accumulate to production of Lactic acid/CO2 during the exercise; To maintain the osmotic balance kidneys conserve sodium ions (Na+); and reabsorb water (in the kidney tubules); Leading to reduction in the volume of urine produced; During exercise the kidney tend to filter out urine releasing more in the urine; (d) Skin - Due to increased muscle activity during physical exercise are sweats(more); Eliminating Nitrogenous wastes/ excess water; through the skin/sweat pores) cooling the body; After (water in) sweat evaporates the increased internal body temperature also leads to dilation of superficial blood vessels (vasodilation)/ blood flowing near the skin; leading to loss of excess heat (to the atmosphere) by radiation/ convection; the hair on the skin surface also lie Flat to allow for loss of heat( to the environment) by radiation/convection; 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 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 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 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 2019PP1QN15
Distinguish between guttation and transpiration.
answers
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 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 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 2018PP2QN01
The diagram below illustrates a section of the mammalian kidney.
​(a) Name the structures labelled E and F.
E F (b) Explain the processes that take place in the regions labelled G and H. Region G Region H
answers
​ (a) E—Glomerulus;
F — Interlobular artery/branch of renal artery; (b) Region G At the (glomerulus), the afferent arteriole which brings blood to the glomerulus is wider than the efferent arteriole; this creates high pressure; leading to ultrafiltration; At the proximal convoluted tubule /distal convoluted tubule, substances required by the body/amino acid substances required by the body (amino acids/glucose/vitamins! some water; are selectively re-absorbed (into the blood stream); hence selective reabsorption; Region H At the descending arm of/limb of the Loop of Henle, water is selectively reabsorbed; At the ascending arm/limb of the Loop of Henle, sodium ions/salts are actively/selectively reabsorbed; At the collecting duct, water is (selectively) reabsorbed: K.C.S.E Biology Q & A - MODEL 2018PP1QN27
Below is a graphical representation of how basal metabolic rates compare in Various animals.
​From the graph, explain why the mouse has a higher breathing rate than the elephant.
answers
K.C.S.E Biology Q & A - MODEL 2018PP1QN26
State two advantages terrestrial animals have in excreting urea as their main nitrogenous waste product.
answers
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