The enzyme that breaks down starch into sugar in the mouth is: MCQ with Answer and Explanation

Explanation:
The brain is the central and most complex organ of the nervous system, processing sensory information, controlling motor functions, and regulating higher cognitive processes. The heart is a muscular organ that acts as the central pump of the circulatory system, propelling blood through the network of blood vessels to deliver oxygen and nutrients. The lungs are a pair of spongy, air-filled organs that are the primary components of the respiratory system, facilitating the vital exchange of oxygen and carbon dioxide. All statements are correct.

Explanation:
Sedimentary rocks, such as limestone, shale, and sandstone, form in layers from accumulated sediments and preserve remains of organisms as fossils. Igneous rocks from volcanic activity and metamorphic rocks formed under high temperature/pressure rarely contain fossils. The fossil record provides evidence for evolution, showing gradual changes in species over geological time. Fossils include bones, shells, imprints, and amber inclusions.

Explanation:
Azolla is an aquatic fern that harbors the nitrogen-fixing cyanobacterium Anabaena azollae in its leaf cavities. It is extensively used as a biofertilizer in rice paddies, adding organic nitrogen. Rhizobium fixes nitrogen in legume roots, Azotobacter is free-living in soil, mycorrhiza is a fungal association enhancing phosphorus uptake. Azolla multiplies rapidly and improves soil fertility.