ICSE Class 8 Biology Oxford Chapter 07 Food Production 1

Food Production and Management I

Learning Outcomes

Useful microorganisms

Sericulture

Apiculture

Pisciculture

Poultry farming

Livestock farming

Protection of animals against diseases

Observe pictures (a) to (c) carefully. Do you know where each of these products is obtained from? All three products shown in these pictures are obtained from animals. In this chapter, we will discuss some useful microorganisms and animals and the products obtained from them.

Useful Microorganisms

You must have learnt about microorganisms (bacteria, fungi, algae, etc.) in class 7. There are bacteria, fungi, and algae from which we benefit immensely and hence they are considered to be useful microorganisms.

Useful Bacteria

Several industrial products, which have wide commercial applications, such as ethyl alcohol, acetone, acetic acid, etc., are obtained through bacterial action known as fermentation. The familiar household process of curd setting is fermentation of milk sugar (lactose) into lactic acid by the action of a bacterium.

Bacteria are used for imparting special flavours to products such as cheese (Fig. 7.1), tea, coffee, cocoa, and tobacco. They are also involved in the preparation of life-saving drugs such as antibiotics and in the preparation of B-complex vitamins. Fibres from coconut husk, jute, hemp, and flax are loosened by the digestive action of bacterial enzymes. Bacteria also help in the process of making leather from animal hides - bacterial enzymes are used to digest the unwanted tissues on the hide.

Useful Fungi

Yeast is used in the baking industry to make bread light and fluffy. Cereals, grapes, and a variety of other products are fermented to obtain alcoholic beverages. Certain antibiotics are also manufactured from fungi (e.g., Penicillin).

Useful Algae

Seaweeds are a source of food and are rich in vitamins and minerals. Some species of algae (e.g., Spirulina and Chlorella) are used as nutritional supplements (Fig. 7.2). Various chemicals of industrial importance too are extracted from them. A laboratory culture medium known as agar is obtained from red algae. A type of algae known as diatoms is the source of silica for several industrial applications.

Useful Animals

Ancient humans hunted animals and ate their flesh. They used the hides and furs of animals for clothing; their skins as containers; their bones and horns as tools and weapons; their teeth, claws, and feathers as ornaments; and their fat as fuel. Domestication of animals started around 12,000 B.C. The bond between humans and animals useful to them has been strengthened over the years. Farmers rear cattle for milk, meat, and work; goat for milk and meat; sheep for wool; pigs for meat; poultry for eggs and meat; bees for honey; and silkworms for silk.

The bond between man and animals has developed into distinct scientific disciplines such as sericulture, apiculture, pisciculture, poultry, and livestock farming.

Sericulture

The raising and care of silkworms (larvae of silk moth) for the production of raw silk is referred to as sericulture. Of the several types of silk moths, Bombyx mori is most widely used in sericulture. Bombyx mori completes its life cycle in four stages: egg, larva, pupa, and adult.

The eggs are small, slightly yellowish, and are covered by a smooth, hard chitinous shell.

When the embryo completes its development, it hatches out of the egg in the form of a larva. The larvae feed on mulberry leaves.

The mature larva stops feeding and starts spinning silk around its body to form a cocoon. The cocoon is made of a silken thread which is over 500 metres long.

The adult moth emerges from the cocoon at the end of the pupal stage.

Nearly 55,000 cocoons are required to obtain a kilogram of silk.

The adult moth emerges from the cocoon by cutting a hole into it, which damages the silk thread. Therefore, silk extraction is done before the moth emerges from the cocoon.

For the purpose of silk extraction, ten day old cocoons are immersed in hot water. This kills the pupa in the cocoon.

The silk thread is skillfully unwound from the cocoon and threads drawn from several cocoons are twisted into yarn.

Teacher's Note

Sericulture demonstrates how humans have developed sustainable practices around insect farming, similar to how traditional families in rural India still maintain small sericulture units for additional income.