1. Fighting Disease Answer the questions shown below as you work through all the slides in the activity set. Email your answers to Ms. Shaikh before the end of the lesson. Isha Lamba, 7D

2. Fighting Disease 1. What is a disease? A disease is a condition in which the health of a person decreases because of the change in the body caused by infection or some other reasons. 2. Are all diseases spread by microbes? No, all diseases are not spread by microbes as some are caused by causes other than infection (like vitamin deficiencies and cancer) and some other with unknown causes. 3. What is an ‘infectious disease’? An ‘infectious disease’ is a disease that is spread from one infected person to another, because of transmission of the microbes. 4. How do we know when someone is ill? When someone is ill, the person experiences symptoms and shows signs like fever, coughing, sneezing, rashes, swelling, headache, etc.

3. Fighting Disease 5. What are the main features of viruses? Viruses are non-living and do not have a cell membrane and cytoplasm. They are made up of a protein coat inside which is genetic material. They infect the host cells and make it produce its own copies. 6. How does a virus reproduce? A virus first invades the living cells by breaking through the cell membrane and makes the cell replicate its own copies to reproduce. In the process it destroys the host cell. 7. List some non-viral microbes/features. Bacteria, protozoa are examples of non-viral microbes. They have cytoplasm and organelles inside them and show all signs of living organisms namely, movement, respiration, sensitivity, growth, reproduction, excretion and nutrition.

4. Fighting Disease 8. Draw a labeled diagram of a bacterium (lots of them are called bacteria) 9. What features do bacteria have? Bacteria have a cell wall and a cell membrane surrounding the cytoplasm. Inside there is genetic material, but not surrounded by a nuclear membrane in form of a well defined nucleus. They show all features of a living organisms. Not all bacteria cause disease. 10. Name 2 diseases caused by bacteria Tuberculosis, Typhoid, Dysentery and Salmonellosis are some of the diseases caused by bacteria.

5. Fighting Disease 11. Which factors prevent the spread of disease? The strong immunity, good nutrition, and personal hygiene prevent the spread of disease. 12. Draw a table to show the names of some infectious and non-infectious diseases. 13. What are antibiotics and who discovered them? Antibiotics are those medicines that kill bacteria helping to treat infectious diseases. Alexander Fleming discovered the antibiotics .

6. Fighting Disease 14. Explain how our bodies protect us from pathogens (disease causing microbes). Our bodies protect us from pathogens through various defense mechanisms including the skin barrier, White blood cells – which produce antibodies and engulf the invading microbes. Also platelets plug the broken blood vessels by forming a clot. 15. A toxin is a poison made by infectious microbes. Explain how white blood cells help us get better. White blood cells produce antibodies as well as engulf the invading microbes. Thus they act as soldiers in the body killing microbes. 16. What is the difference between an antibody and an antitoxin? Antibodies are produced by the same person who has got exposed to the infecting microbe or has received vaccination made from the same microbe while antitoxin is produced somewhere else and is given ready made to the person who is infected by the microbe and has weak immunity.

7. Fighting Disease 17. What gives us immunity towards a disease? Exposure to the antigens of the microbe, good nutrition and immune system results in immunity towards a disease. 18. Listen to the narrations about the graphs to explain: * What is meant by ‘incubation period’? Incubation period is the period between the entry of microbe in the body and the development of the first symptoms of the disease. * How does the number of viruses in the body relate to a patient’s body temperature? The temperature of the patient’s body increases with the number of viruses in the body. It is maximum, when the number of viruses is maximum. * Why a patient’s temperature remains normal when he just catches a virus? Because the virus is in very small number and has not yet spread everywhere to be able to cause a major change in the body. * What do antibodies do to the virus? Antibodies gather around the virus and cling on to it, making it immobile and neutralize it. 19. Compare natural and artificial immunity and give some examples Natural immunity is obtained either by experiencing the infection by the microbe or by receiving the antibodies from mother through placenta or milk, e.g. when one falls sick with an infection he develops natural immunity to it. The artificial immunity is obtained through the vaccination using either killed or weakened microbes or ready-made antibodies made in another host e.g. when people took influenza or H1N1 vaccination they developed artificial immunity.

8. Fighting Disease 20. What is your total score out of 10 marks? How many mistakes did you make? 9 out of 10. I made one mistake.