Question 7
- (i) what is pollution? [3 marks]
(ii) name four pollutants that could be present in water fetched from a stream. [4 marks]
- Describe two methods that could be used in the home to make stream water safe for drinking.[4 marks]
- (i) explain why it is important to keep houseflies away from food? [3 marks]
(ii) state one method of domestic refuse disposal. [1 mark]
- State three signs of a fracture. [3 marks]
Observation
This question was attempted by many candidates and their performance was good. In part (a) (b) (c) they did well because majority of the candidates correctly gave right answers to all sections in it.
The expected answers are as follows:
7 (a)(i) POLLUTION
Is the release of harmful wastes/poisonous substances/pollutants, at high concentration; in the air, water, food or soil; that can harm the living organisms in the environment as a result of human activities and natural events.
(ii) POLLUTANTS THAT COULD BE PRESENT IN WATER FETCHED
FROM A STREAM
- untreated sewage/faeces
- industrial waste substances/chemicals
- agricultural wastes/nitrate/phosphate fertilizers washed off fields
- wastes from human habitation
- hot water from power stations
- oil dumped into rivers/stream
- pathogens/germs/bacteria
(iii) METHODS THAT COULD BE USED IN THE HOME
TO MAKE STREAM WATER SAFE FOR DRINKING
- Filtering
filter the water through a good porcelain filter/clean cloth to remove suspended matter, e.g, bacteria amoebae and their cysts, cyclops and schistosome larvae.
- Boiling
Boil for at least 10 minutes to destroy all harmful organisms.
- Addition of chemicals
addition of correct named chemicals to destroy bacteria, viruses and other micro organisms in the water.
(b)(i) IMPORTANCE OF KEEPING HOUSEFLIES AWAY FROM FOOD
- to prevent them from settling on food, to deposit germs on food/contamination of
food
- houseflies are vectors of many pathogens/named
- spread disease such as cholera and dysentery
- prevent food spoilage/decay
(ii) METHODS OF DOMESTIC REFUSE DISPOSAL
- dumping refuse in pit
- dumping refuse in designated site
- collection of refuse in galvanized steel/plastic dustbins/garbage cans with lid
- buried in pit or trenches
- use of incinerator
- burning method.
(iii) ADVANTAGES OF DUMPING REFUSE IN PIT
- avoid littering of refuse
- diseases cannot be easily transferred
DISADVANTAGES OF DUMPING REFUSE IN PIT
- if left open it is dangerous, because it attracts vector
- it create offensive odour
ADVANTAGES OF DUMPING REFUSE IN SITE
- provide for large collection of refuse
- easily managed
DISADVANTAGES OF DUMPING REFUSE IN SITE
- disease can be spread out in the area
- offensive odour is perceived all the time
- it makes the area unattractive
ADVANTAGES OF USING REFUSE BIN
- avoidance of offensive odour
- avoidance of refuse littering the environment
- prevent spread of diseases
DISADVANTAGES OF USING REFUSE BIN
- if not off loaded on time, it creates offensive odour.
- If attracts flies.
ADVANTAGES OF BURYING REFUSE
- very hygienic because refuse is not exposed
- avoidance of offensive odour
- provides manure to the soil
- prevents spread of diseases
DISADVANTAGES OF BURYING REFUSE
- not popular
- not suitable for large refuse
ADVANTAGES OF INCINERATOR
- very hygienic method
- if well managed, offensive odour is prevented
DISADVANTAGES OF INCINERATOR
- very expensive to construct
- very expensive to manage
ADVANTAGES OF BURNING REFUSE
- prevents littering of refuse
- prevent offensive odour
- kill germs/bacteria
DISADVANTAGES OF BURNING REFUSE
- Pollution of the environment
- Could cause fire outbrake
(c) SIGNS OF A FRACTURE
- cracked/broken bone
- skin surface overlying the fractured bone may be intact/broken/badly bruised/to expose broken bone
- fractured site look distorted/deformed
- site of the fracture may be swollen/hot
- difficult to move the injured part/injured part not functional
- sign of shock
- pains at fractured site