Test: Microorganisms : Friend Or Foe - 2 - Class 8 MCQ

Influenza is an infectious disease caused by the influenza virus. It is also known as flu symptoms include high fever, running nose, sore throat, headache, coughing and muscles pain etc. Typhoid, dysentery and cholera are bacterial infections.

• Preservatives such as vinegar, common salt, and oil are used to prevent the spoilage of foods and protect them from microbial infection.
• Vinegar and salt create an environment that inhibits microbial growth, while oil can create a barrier to prevent microorganisms from reaching the food.
• Therefore, all of these substances are effective in preserving food in the kitchen.

Lichens is an association between fungal and an algal species. It is a mutually benefiting association where algae provide food to the fungus and in return gets shelter from it.

• Statement B is incorrect.
• All fungi are not made up of fine threads; while many fungi do have a filamentous structure called hyphae, Penicillium and other fungi also consist of such threads.
• Penicillium, like other fungi, has hyphae and does not differ in this fundamental structure.

• It produces carbon dioxide, causing dough to rise – This is the main role, as the carbon dioxide gas produced by yeast makes the dough expand and become fluffy.

Penicillin is an antibiotic derived from the mold Penicillium notatum. Here's a brief explanation of how this works:

1. Discovery: Penicillin was discovered by Alexander Fleming in 1928. He observed that a mold growing on a Petri dish containing Staphylococcus bacteria inhibited bacterial growth. The mold was identified as Penicillium notatum.

2. Production: The mold Penicillium notatum produces penicillin as a secondary metabolite. This means that penicillin is not essential for the mold's growth but helps it compete with other microorganisms in its environment. Penicillin interferes with the cell wall synthesis of bacteria, leading to their destruction.

3. Extraction and Use: Penicillin is extracted from the mold through a fermentation process. The mold is grown in a controlled environment, and the penicillin is then purified from the culture. Penicillin was the first antibiotic used to treat bacterial infections and has been crucial in medicine for its effectiveness against a range of bacterial diseases.

In summary, the mold Penicillium notatum is the microorganism responsible for producing penicillin, making it a critical part of the history and development of antibiotics.

• a) Antibodies are specific molecules produced against invading microbes.
  This statement is correct. Antibodies are indeed specific proteins produced by the immune system to target and neutralize pathogens.

  b) Tuberculosis is an infectious airborne disease.
  This statement is also correct. Tuberculosis (TB) is spread through the air when an infected person coughs or sneezes.

  c) Anthrax are the antimicrobial agents for inhibiting the growth of microbes.
  This statement is incorrect. Anthrax refers to a disease caused by the bacterium Bacillus anthracis, not an antimicrobial agent.

  d) Yeast are used in the wine industry.
  This statement is correct. Yeast, particularly Saccharomyces cerevisiae, is used in the fermentation process to produce wine.