(a) Completion of table on weeds
WeedBotanical nameMethod of dispersalGoat weed Ageratum conyzoides Animal Wind Siam weed Chromolaena odorata Wind Water leaf Talinum triangulareExplosive mechanism/self explosion


(b) Factors affecting land availability for agriculture
(i) Physical factors
- Soil type - Topography
- Land degradation - Soil pollution
- Soil fertility
- Soil properties such as texture and structure

(ii) Economic factors
- Population pressure/housing - Expansion of industries
- Mining/mineral exploitation - Recreation/tourism
- Transportation - Construction of markets

(c) Effects of pollution on agricultural lands and ponds
- Death of aquatic organisms - Contamination of crops
- Loss of income/investment - Contamination of water
- Disruption of ecological balance - May increase cost of production
- Crop failure/death

(d) Ways of minimizing land and pond pollution
- Controlled application of herbicides - Proper disposal of sewage
- Controlled application of fertilizers - Proper disposal of animal wastes
- Controlled application of pesticides - Fencing of ponds
- Proper maintenance of oil pipelines to prevent spillag
- Adoption of organic farming