Which ion is essential for the blood clotting process? MCQ with Answer and Explanation

Explanation:
Nitrous acid (HNO₂) is a chemical mutagen that can deaminate bases (e.g., cytosine to uracil), causing base-pair changes and mutations. X-rays, UV radiation, and gamma rays are physical mutagens (ionizing and non-ionizing radiation). Chemical mutagens include base analogs, alkylating agents, and intercalating agents. Mutagens increase the rate of mutations beyond natural levels.

Explanation:
The common cold is a viral infection of the upper respiratory tract, primarily caused by rhinoviruses. Typhoid fever, caused by Salmonella typhi, is transmitted via the fecal-oral route through contaminated food and water. Plague, caused by Yersinia pestis, is a zoonotic disease transmitted to humans primarily by the bite of infected rat fleas (Xenopsylla cheopis). All three statements are correct.

Explanation:
Anthrax is a zoonotic disease caused by the spore-forming bacterium Bacillus anthracis. It can infect skin, lungs, and gastrointestinal tract. Streptococcus pyogenes causes strep throat, Salmonella typhi typhoid, Vibrio cholerae cholera. Anthrax spores can survive for decades in soil and have been used as a bioweapon.