3. (a) (i) What is meant by respiration? [2 marks]
(ii) List four respiratory diseases [4 marks]
(iii) State four ways of preventing respiratory diseases [4 marks]

(b) State four differences between inhalation and exhalation in humans [4 marks]

(c) Explain briefly the following processes associated with the treatment of water: 
(i)  Chlorination;
(ii)  Flocculation;
(iii) Filtration.

                                   
                     
                     

OBSERVATION

This question was attempted by many candidates and their performance was fairly good. In part (a) (i) candidates correctly define respiration, in (a)(ii) candidates correctly listed respiratory diseases, in (a)(iii) candidates correctly stated ways of preventing respiratory diseases. In part (b) candidates correctly stated differences between inhalation and exhalation in humans. In part (c) candidates could not correctly explain the following processes associated with the treatment of water (i) chlorination (ii) flocculation (iii) filtration.
However, the expected answer were as follows:    
                                             
    3(a)(i)  Respiration                 
    -    respiration is the release of energy from food with/without the use of
oxygen in living organism
OR
- it is the exchange of gasses
- between organism and its environment

            (ii)      Respiratory diseases
common cold
influenza
whooping cough/pertussia
bronchitis
diphtheria
pneumonia/asthma
lung cancer
hay fever
tuberculosis
Spelling must be correct to score

          (iii)       Ways of preventing respiratory diseases
involve in regular exercise
avoid exposure of chest to extreme cold/very cold drinks
isolation of victim of respiratory diseases
immunization against respiratory diseases
avoid dusty areas so as not to damage the cilia of mucous membrane
adequate ventilation/avoid overcrowding.

(b) Differences between inhalation and exhalation of air in human
Inhalation
the diaphragm muscles contract
the intercostals muscles contract
the volume of thoracic cavity increase
the ribs move upward and outward
the diaphragm is flattened
percentage of O2 is high
percentage of C02 is low
moisture content is low

(c) Explanation of terms
Exhalation
the diaphragm muscles relax
the intercostals relax
the volume of thoracic cavity decreases
the ribs move down and inward to their
original size
the diaphragm becomes dome shaped
percentage of O2 is low
percentage of CO2 is high
moisture content is high

        (i)          Chlorination
- this is the treatment of water with chlorine
- to kill micro-organisms in water
        (ii)         Flocculation
- addition of alum
- to settle/precipitate particles from water
           (iii)        Filtration
- use of filter/sieve - to separate solid suspended particles form the water