1. What is biological Science?

       It is the science or a study of living organisms - plants, animals and micro-organisms. It includes all aspects of living organisms such as the appearance, internal and external structure, functioning (feeding, breathing, moving, growth, development, reproduction, propagation etc.) and how the living organisms adjust to changes in their surroundings and solve the problems encountered in their lives.

 2.What is the  meaning of the word 'Biology'? Who coined the term?

    The word biology is a Greek word . '  Bios' means life and ' logos means 'study of ' or ' science of ' . The term was coined by a French scientist Jean Lamarck.

   3.Biology is not a science of recent  origin - Justify?  

      Biology is  one of  the oldest branches of science. Since the emergence of human race on earth, man has been studying biology. Man was interested to know about his birth, growth, diseases and death. Man learnt to observe plants and animals around him and applied this knowledge to the betterment of human race. Man found that plants and animals can provide him  food, shelter, clothing and medicines. Since ages he has been trying to improve both plants and animals using modern techniques.

 4. Knowledge in biology was not gained in a day or  two. Justify?

      Early men were nomads who wandered in the forests and mountains hunting and collecting food. In this process, he collected information about various plants and animals which were helpful and useful to him. This knowledge was passed on from generation to generation, because it was very important  for his survival. So biology is a science that accumulated over a period of several centuries.

 5. Why is the period of thousand years after the death of Aristotle and Galen known as ' Dark Age of Science '?

      The earliest written records of biology is that of Aristotle ( 384 - 322 BC) and of Galen (130 - 200 AD). No systematic studies were carried out in biology for the next thousand years. During this period, religious studies dominated scientific studies. Hence this period is known as  Dark Age of Science. 

 6. What are the two ways in which food production can be increased?

        Food production can be increased in two  ways: 

          1.  Increase the land area under agriculture.

          2. Produce more food in the available land area. 

7. What are the problems created when we increase the land area  for agriculture?

       To increase the land area for agriculture we have to clear forest areas. This results in the destruction of forests. Destruction of forests leads to serious environmental problems.

  8. What are the effects of deforestation?

      The effects of deforestation are:

                  1. It upsets the natural balance between plants and animals.

                  2. It decreases the rainfall.

                  3. It decreases the amount of underground water.

                  4. It increases soil erosion.

 9. It is better to produce more food in the available agricultural land. Suggest two ways to achieve this.

         1. Provide more nutrients to plants by applying fertilizers. Biofertilizers and compost can be used instead of chemical fertilizers.

         2. By selective breeding and hybridization, plants that produce more food in a short time have been developed. They require less amount of  fertilizers but yield more food.

 10. Application of chemical fertilizers to crops is not a good practice - Why?

      Chemical fertilizers change the properties of agricultural land. Prolonged use of  fertilizers will make the land useless. It increases the cost of production and thereby increases the cost of food. 

11. Application of chemical pesticides is hazardous to man and environment. Why? 

 Chemicals cause many  health hazards to man and animals because it poisons food.  Disease causing bacteria, viruses, fungi and insects develop resistance to these chemicals. To overcome this problem, either large amounts of  organic chemicals or new chemicals which are nontoxic  have to be applied. This increases the cost of production.The chemical fertilizers pollute the land and water bodies.

12. What is Biological control ?

       Biological control is an environmentally sound and effective means of reducing or mitigating pests and pest effects through the use of natural enemies.

13. What is selective breeding? 

       To improve the productivity of plants, and also to develop improved breeds of animals, selective breeding is used. In this method, parent  plants with desired qualities are selected and crossed. Seeds collected are germinated and the plants with good qualities are selected. Plants and animals produced by selective breeding are called hybrids. 

14. How can you reduce the use of insecticides and pesticides in agriculture ?

   By selective breeding and hybridisation, plants resistant to diseases have been developed. Farmers can use these hybrids for cultivation. Biological control of insect pests can be a good option for farmers. Neem seed oil, tobacco decoction and other products of plant origin can be sprayed to control pests. 

15. What are the uses of hybridisation and selective breeding? 

1. Plants and animals with better quality and yield can be developed.

       2.   Disease resistant  varieties can be developed.

       3.   Plants that produce more food in a short time can be developed. 

16. What is tissue culture ? 

     In this method cells are taken from selected parts of a plant and grown in a test tube under highly controlled conditions. These cells grow and divide and give rise to a new plant. By  tissue culture, a large number of plants with good quality can be obtained in a short time. 

17. How is genetic engineering applied in tissue culture? 

       Plant cells are cultured and genes responsible for desired characters are introduced in the cells. These cells grow into a new plant that will have the desired characters. 

18. How does genetic engineering  help agriculture? 

    By genetic engineering plants which give higher yield, crops which can resist conditions such as draught, increased salt content in the soil and plants which are resistant to diseases are produced.

 19. How is genetic engineering done in animals? 

     Genes responsible for desired characters are transferred to eggs. These eggs are allowed to develop into adults. These animals will be disease resistant, high yielding and adaptable to environmental conditions. 

20. Name some methods of food preservation? 

     Drying, pasteurisation, sterilisation, pickling, freezing, chemical treatment and canning. 

 21. What is health ? How are diseases caused? 

    Health is a state of physical, mental and social well being. 

  A disease may be due to entry of micro-organisms or due to disturbances in the functioning of  various organ systems of the body.

 22. What is the role of biology in human health and disease? 

      Biology helps in finding out the causes, cure and methods of prevention of diseases in man.  

23. Name an antibiotic. Name  the organism  that produces it. How does it help man ? 

        1. Penicillin

        2. Penicillium notatum  (fungi)

        3. Antibiotics save human life from infections by killing the  bacteria that infects human beings.  

24. What are Vaccines? 

     Inactive, half  killed or dead micro organisms are injected into the human body so that it stimulates the production of antibodies, in the  blood. Vaccination helps us to fight diseases and prevents the spread  of epidemics.  

25. How can  Insulin  be produced in large amounts at a very low cost?

      By genetic engineering, genes responsible for the production of insulin is isolated and introduced into bacteria. These bacteria are grown in large numbers and insulin can be collected in large amounts, at a very low cost. 

26. What  is  Gene therapy ? How is it useful in treatment of diseases? 

     Some diseases are produced by genetic defects caused by mutation of genes. In gene therapy  the defective genes are identified  and replaced by normal genes. This can save people with genetic defects without using drugs.  

27. Biology helps to improve the living conditions and environment around us. Justify?

     Afforestation programmes are taken up to convert large tracts of lands into forests. Rivers are cleaned up. Chemical fertilizers and pesticides are substituted by natural biofertilizers and organic substances. Industries develop methods to reduce pollution.  Automobiles are designed to reduce pollution. 

28. Biology appeals to the aesthetic sense of man - How?

   Study of  biology provides an avenue for recreational activities. For example development of gardens, parks, lakes and  zoos, helps us to spend our  free time in a useful manner,  because it appeals to our aesthetic sense.

 29. What is mutation?

   A sudden heritable change occurring in the genetic material of an organism is called mutation. Mutation causes genetic disorders and diseases.

30. Name six vaccines which help us to fight diseases?.  

      1. BCG     2. OPV     3. DPT     4. MMR     5. Hepatitis-B vaccine     6. Chickenpox vaccine.