The process that moves food through the esophagus by rhythmic contractions is: MCQ with Answer and Explanation

Explanation:
Bones store minerals (1) and contain marrow for hematopoiesis (2). Ligaments connect bone to bone; tendons connect muscle to bone. So 3 is incorrect.

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:
Producers (green plants, algae, cyanobacteria) form the first trophic level, converting solar energy into biomass. Consumers depend on them.