![Answers
Objective Questions 1D
2C
J2]nJ
4A
5B
IftDD
7B
8B
9A
10c
11 B
t2D
13D
t4c
lsc
Structured Question
(a) 20km
(b) (t) Poiiution of the river water reduces the number of fish, decreases the concentration
of dissolved oxygen in the water and increase the number of bacteria. (ii) Domestic waste disposal / rvaste materials
(c) 1 Lorv rate of fish reproduction
2 Lack offish food because ofdependence on producer
Essay Question (a) The quantity of oxygen that is requrred by the microorganisms to deeompose the
organic substances in the water.
(b) . Wastes/domestrc uaste matenal e DecomposeC b,v decomposing bactena o Increase the usage oforygen
r Flou, of hot u'ater from the factones increase the lvater temperature o Decrease the solubility of orygen in ihe rvater o Florv of organic fertilisers from agricultural areas o Encourages algae growth. which prevents light from reactung the bottom of the lake o Decrease the rate of photos.r,nthesis and decrease the rate of oxygen release o Aquatic animals die as a result of a lack of ox-_vgen o DecomFosition of dead animals (and plants) increases B.O D. o The effect of B.O.D. increase is the death/migration of aquatic animals
(c) 1 Replace cFC with easily biodegradable substances such as HCFC
- reduce the thinning of the ozone la.v-er 2 Process the faciory/domestic rvaste products/filtered cilmneys
- reduces water pollution that is caused by the decomposition of organic substances 3 Prepare a special disposal area for radioactive substances I metal
- reduce environmental poliution that is caused b,-v raciioactive rays 4 Recycle substances such as glass/plastic lp ap er I aluminium
- maintain natural resources
5 Use electric/soiar powered vehicles to reduce air poiiution that is caused by
hydroearbon gases
6 Bum garbage in incinerators to reduce soil and air pollution. 7 change oil paim remains into biogas to maintain naturar resources
B Use biotechnology methods to clean up oil spills in order to control water pollution 9 Design houses that save energy
- reduce the usage of substances tbr air-conditioners
i0 Cloud seeding to reduce haze resulting from forest bumrng](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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Biology form 4 chapter 8 9
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- 2. Answers Objective Questions 1D 2C J2]nJ 4A 5B IftDD 7B 8B 9A 10c 11 B t2D 13D t4c lsc Structured Question (a) 20km (b) (t) Poiiution of the river water reduces the number of fish, decreases the concentration of dissolved oxygen in the water and increase the number of bacteria. (ii) Domestic waste disposal / rvaste materials (c) 1 Lorv rate of fish reproduction 2 Lack offish food because ofdependence on producer Essay Question (a) The quantity of oxygen that is requrred by the microorganisms to deeompose the organic substances in the water. (b) . Wastes/domestrc uaste matenal e DecomposeC b,v decomposing bactena o Increase the usage oforygen r Flou, of hot u'ater from the factones increase the lvater temperature o Decrease the solubility of orygen in ihe rvater o Florv of organic fertilisers from agricultural areas o Encourages algae growth. which prevents light from reactung the bottom of the lake o Decrease the rate of photos.r,nthesis and decrease the rate of oxygen release o Aquatic animals die as a result of a lack of ox-_vgen o DecomFosition of dead animals (and plants) increases B.O D. o The effect of B.O.D. increase is the death/migration of aquatic animals (c) 1 Replace cFC with easily biodegradable substances such as HCFC - reduce the thinning of the ozone la.v-er 2 Process the faciory/domestic rvaste products/filtered cilmneys - reduces water pollution that is caused by the decomposition of organic substances 3 Prepare a special disposal area for radioactive substances I metal - reduce environmental poliution that is caused b,-v raciioactive rays 4 Recycle substances such as glass/plastic lp ap er I aluminium - maintain natural resources 5 Use electric/soiar powered vehicles to reduce air poiiution that is caused by hydroearbon gases 6 Bum garbage in incinerators to reduce soil and air pollution. 7 change oil paim remains into biogas to maintain naturar resources B Use biotechnology methods to clean up oil spills in order to control water pollution 9 Design houses that save energy - reduce the usage of substances tbr air-conditioners i0 Cloud seeding to reduce haze resulting from forest bumrng