The 10% law of energy transfer in a food chain was proposed by: MCQ with Answer and Explanation

Explanation:
Selman Waksman and colleagues isolated streptomycin from Streptomyces griseus in 1943, the first effective treatment for tuberculosis. Fleming discovered penicillin, Pasteur developed vaccines, Koch identified TB bacterium.

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:
In 1953, Stanley Miller and Harold Urey conducted an experiment to test the Oparin-Haldane hypothesis of chemical evolution. They simulated the reducing atmosphere of primitive Earth, which they believed lacked free oxygen. The gas mixture used was methane (CH4), ammonia (NH3), hydrogen (H2), and water vapor (H2O). By applying electrical sparks (simulating lightning), they successfully synthesized amino acids and other organic compounds.