CBSE Questions for Class 8 Biology Microorganisms Friend And Foe Quiz 2 - MCQExams.com

1. To increase milk safety for the consumer by destroying disease-causing microorganisms (pathogens) that may be present in milk.
2. To increase keeping the quality of milk products by destroying spoilage microorganisms and enzymes that contribute to the reduced quality and shelf life of milk.

Typhoid is a bacterial infection that can lead to a high fever, diarrhoea, and vomiting. It can be fatal. It is caused by the bacteria Salmonella typhi. The infection is often passed on through contaminated food and drinking water. When the fly lands on a food item or surface, the disease-causing agent can get transmitted via the body hairs and legs.

Thus, the correct answer is option A. 

• Communicable diseases are the diseases that can spread from one person to another by various means like by contact, through the exchange of body fluids, etc. 
• Common cold can spread by sneezing in public without covering the mouth. The pathogens can then enter the body of a healthy person through the nostrils when the contaminated air is inhaled. 
• Chickenpox can spread through contact by touching the fluid from the blisters of the infected person. 
• Diabetes is a non-communicable disease.

• When the food is not edible to humans or its quality of edibility becomes reduced is called food spoilage.
• Various external factors are responsible for the spoilage of food.
• Several methods of prevention can be used that can either totally prevent, delay, or otherwise reduce food spoilage such as the addition of chemical preservatives, refrigeration, freezing, heating/ boiling of foods above the danger zone (140$$^{\circ}$$F/60$$^{\circ}$$C) for over 24 hours and canning of food can preserve food for a particularly long period. 
• Thus, the correct answer is option D.

• Pathogens are life forms that transmit diseases which result in various illness in humans, animals, plants and other living creatures. Viruses, Bacteria, Fungi and Protozoans are pathogens responsible for various diseases. 
• Thus, Option D is correct.

• Fermentation is the process that is carried by the anaerobic respiration of microorganisms which leads to the production of lactic acid or alcohol with the release of carbon dioxide. 
• Yeasts can convert sugars to alcohol and carbon dioxide by fermentation.