The disease caused by the deficiency of vitamin B₁₂ and folate leads to: MCQ with Answer and Explanation

Explanation:
Nitrification is a two-step process in the nitrogen cycle where ammonia is oxidized to nitrates. First, ammonia (NH3) is converted to nitrites (NO2-) by bacteria like Nitrosomonas. Then, nitrites are converted to nitrates (NO3-) by bacteria like Nitrobacter. Nitrates are the primary form of nitrogen absorbed by plants. Denitrification is the reverse process, converting nitrates back to nitrogen gas.

Explanation:
Ciliated pseudostratified columnar epithelium (with goblet cells) lines the trachea and bronchi; the cilia beat in coordinated waves to move mucus and trapped particles out of the airways. Squamous epithelium is flat (alveoli), cuboidal in kidney tubules, transitional in urinary bladder.

Explanation:
Transitional epithelium (urothelium) is stratified, with cells that can change shape from cuboidal to squamous when the bladder distends. It lines the renal pelvis, ureters, bladder, and part of the urethra. Squamous is flat, cuboidal cube-shaped, columnar tall.