1. The techniques of bringing about improvements in living organisms by artificial genetic changes and by hybridization for the welfare of human beings, are together called ‘Biotechnology’.
2. It includes the techniques of genetic engineering and tissue culture.
3. Genetically Modified Crops (GM crops) are being produced by introducing changes in DNA of natural crops.
4. Some naturally occurring varieties cannot withstand environmental stresses like frequently changing temperature, wet and dry famines, changing climate, etc. However, GM crops can grow in any of such adverse conditions.
5. As GM crops are resistant to insects, pests, pathogens, chemical weedicides etc. the use of harmful chemicals like pesticides can be avoided.
6. Due to use of seeds of GM crops, there is improvement in nutritive value and decrease in loss of crops.

• Biotechnology includes the techniques of genetic engineering and tissue culture.
• Ex vivo growth of cells or tissues in an aseptic and nutrient-rich medium is called tissue culture.
• Tissue culture can be used to grow those plants on a large scale, which bear flowers, fruits of excellent quality.
• Plants produced by tissue culture and genetic modification techniques are disease-free and pest resistant.
• It has thus become possible to produce sufficient food grains for our huge population.
• It has helped to increase the ability of plants to with stand environmental stresses.
• Vaccine production, early diagnosis of congenital diseases, organ transplant, cancer research, production of artificial skin, cartilage, etc. in laboratories has become possible.

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• A group of cells having the same origin, same structure and same function is called a ‘tissue’.
• Some cells in the body of living organisms are ‘totipotent’, that is if provided a proper environment, a new organism can grow from these cells.
• ‘Ex vivo growth of cells or tissues in an aseptic and nutrient-rich medium’ is called tissue culture.
• Nowadays, a complete organism can be developed from a single cell or from tissue with help of the tissue culture technique.
• A liquid, solid or gel-like medium prepared from agar, which supplies nutrients and energy necessary for tissue culture is used in this technique.
• Tissue culture involves taking the required tissue from the source plant, its primary treatment, Reproduction / Multiplication, Shooting and rooting, primary hardening and secondary hardening.

1. Livestock are domesticated animals raised to complement agriculture.
2. They provide farm labour and other commodities such as meat, eggs, milk, wool etc.
3. Sheep can grow on trees and shrubs that grow in the wild and also on farm waste.
4. The sheep provides us with meat, wool and skin.
5. Besides their droppings is an excellent fertilizer as there is more nitrogen, phosphorus and potash in it.
6. It is thus profitable to rear sheep and so it is considered a livestock.