Question

Which substance of saliva destroys the harmful bacteria?
A. Cerumen
B. Chyme
C. Lysozyme
D. Secretin

Answer 1

Hint: The saliva is an extracellular fluid that is produced and secreted by the salivary glands present in the mouth. The saliva consists of water, mucus, white blood cells, enzymes, epithelial cells, antimicrobial agents. This substance is a naturally occurring enzyme found in bodily secretions.

Complete answer: In humans, the lysozyme is a part of the innate immunity which forms the first line of defence against infections. It has an antimicrobial function as a result of which, it breaks down the carbohydrates of the bacterial cell wall and kills the bacteria. The lysozyme is present in the saliva and protects the oral cavity by acting as a cell lysing agent against pathogens. At the time of inflammation, the lysozyme concentration is increased. The lysozyme has antimicrobial properties and fungicidal properties as well, as it protects the mucosal area from the invasion of the pathogen such as the yeast or fungi.
a) The ceruminous gland is the specialized sweat glands that are located in the auditory canal.
b) The chyme is an acidic fluid that is present in the stomach and passes to the small intestine which consists of the gastric juice and the partly digested food.
c) The secretin is a hormone that is released in the bloodstream by the duodenum in the response to the acidity which stimulates the secretion by the liver and the pancreas.
Hence, the correct answer is option C.

Note: Lysozyme is also present in tears and milk. It cleaves the peptidoglycan component of the bacterial wall. It was discovered in 1921 by Sir Alexander Fleming. It is also present in cytoplasmic granules of macrophages and the polymorphonuclear neutrophils. It is also known as muramidase.