Which endocrine gland is known as the 'master gland'? MCQ with Answer and Explanation

Explanation:
Rhizobium is a symbiotic nitrogen-fixing bacterium that forms root nodules in the roots of leguminous plants (like peas, beans, clover). Inside these nodules, the bacterium converts atmospheric nitrogen (N2) into ammonia (NH3), which the plant can use. In return, the plant provides the bacteria with carbohydrates and a protected environment. It significantly reduces the need for chemical nitrogen fertilizers.

Explanation:
Entomology is the study of insects. Ichthyology is fish, herpetology reptiles and amphibians, ornithology birds. Insects are the most diverse group of animals.

Explanation:
Alexander Fleming discovered penicillin in 1928 from the mold Penicillium notatum (later renamed P. chrysogenum). Aspergillus niger is used for citric acid production, Saccharomyces is yeast, Rhizopus is a bread mold. Penicillin was the first true antibiotic and its mass production during WWII saved countless lives. It inhibits bacterial cell wall synthesis.