(a) The principles involved in the following methods of food preservation are:
(i) Salting:- It raises the osmotic concentration of food. and removes water from or dehydrates the food (ex - osmosis) to an intolerable level.
(ii) Refrigeration: It provides lower temperature within the food, retards (slows down) biological processes in spoilage organisms in food and kills some micro-organisms or slows down the activities of spoilage organisms in food.
(iii)Drying: It removes water or moisture and dehydrates food, prevents normal microbial activities which requires water and increases osmotic concentration of food which kills spoilage organism.
(iv)Smoking: It creates or generates high temperature/heat Its carbon kills micro-organisms in food, causes dehydration, increases osmotic pressure and hence, killing of the microbes.
(v) Chemicals: It chokes /suffocates/ spoilage organisms in food, dehydrates/toxicates spoilage organism in food and finally kills organisms.
(b) Problems that may be caused by human over - population are:
(1) Reduction of availability of land for agriculture.
(2) Shortage of food resulting in competition and starvation.
(3) Causes unemployment.
(4) Reduces per capita income/causes poverty.
(5) Causes outbreak of disease / epidemics/ health hazard.
(6) Causes inadequate medical care, social welfare services and shelter.
(7) Leads to increased social vices like crimes, juvenile delinquency, drug abuse e.t.c and aggression.
(8) Causes inadequate educational facilities and other public utility services.
(c) Ways by Which government may increase food production are:
(i) Distribution of high quality seeds and other planting stock which are high - yielding, disease/pest/drought resistant.
(ii) Distribution of fertilizers and other agro - chemicals at subsidized rate to increase crop yield.
(iii) Distribution of tractors/other farm machines/implements for hiring for easy and quicker cultivation of large farm/area of land.
(iv) Providing extension services to local farmers to intimate them with modern farming practices/techniques.
(v) Establishment of river basin authorities which makes water available for irrigation and dry season farming.
(vi) Good roads and stable markets, for easy distribution of products.
(vii) Government should make available storage facility to prevent spoilage.
(viii) Establishment of research institutes to research on food varieties.
(ix) Government should grant agricultural loan to encourage farmers to produce more food.