Class 9 MAHARASHTRA STATE TEXTBOOK BUREAU Solutions Science Chapter 8 - Useful and Harmful Microbes

1. Yeast reproduces asexually by the budding method.
2. Toxins of fungal origin are called mycotoxins.
3. Leguminous plants can produce more proteins due to Rhizobium.

1. Chickenpox. It is caused by a virus, whereas others are caused by bacteria.
2. Yeast. It is a fungus, whereas the rest are bacteria.
3. Rubella. It is a disease in humans, whereas the rest are diseases in plants.

• Dal is rich in proteins.
• During summer, bacteria attack the dal and cause fermentation resulting in the production of carbon dioxide gas.
• Therefore, foam accumulates on the surface of the 'dal' kept for long time in summer.

• Naphthalene balls are balls of chemical pesticides and deodorant.
• They help to kill or repel insects such as moths, cockroaches and mice.
• Therefore, naphthalene balls are kept with clothes to be put away to prevent clothes from getting damaged.

Mode of infection:

• Contact with the infected person or his/her belongings like clothes.

Preventive measures:

• Personal hygiene
• Avoid contact with the infected person

• Hepatitis A and Hepatitis B, DTP (Diphtheria, Tetanus, Pertussis), Polio, MMR (Measles, Mumps, Rubella), Chicken pox, Influenza, Tetanus, BCG and Rotavirus are the common vaccines given to infants.
  
  
• Vaccines consist of dead or weakened microbes. When these vaccines are swallowed or injected, the body produces antibodies to fight the microbes. These antibodies remain in the body and protect it from any future attack of the disease-causing microbes. Therefore, vaccines are given to infants for preventing the occurrence of diseases.

• Vaccines are produced using the disease-causing bacteria or viruses, but in a form that will not harm the human beings.
• They are made from dead or weakened microbes or their toxins.
• Vaccines stimulates the immune system to produce antibodies which give life-long protection against the disease.
• There are specific vaccines for specific diseases.

Antibiotics cure diseases by destroying or preventing the growth of harmful micro-organisms.

• Generally, antibiotics work against harmful bacteria, which attack humans or animals.
• But some of the antibiotics are better suited to humans while some are better for animals. This is due to the adverse effects they show in different species. 
• Also, the dosages of antibiotics for humans and animals is also different.

• Pathogens are microbes which can cause diseases.
• A particular pathogen is cultured and grown in a laboratory for the preparation of a vaccine.
• If these pathogens are not safely stored, they may get modified due to environmental factors, resulting in decrease in the efficiency of the vaccine.
• Also, the live pathogens may escape and cause diseases.

Antibiotics which are effective against a wide range of gram positive and gram negative bacteria are known as broad spectrum antibiotics.

Examples: Chloramphenicol, ampicillin, amoxicillin.

Yeast uses sugar as food. It grows and multiplies rapidly due to the carbon compounds in the sugar solution. In the process of obtaining nutrition, yeast cells convert the carbohydrates in the food into alcohol and carbon dioxide. This process is called fermentation. Bacteria such as Lactobacilli convert lactose, the sugar in milk into lactic acid by the process of fermentation.

Carbon compounds obtained from some bacteria and fungi for destroying or preventing the growth of harmful micro-organisms are called antibiotics.