Dengue fever is transmitted by the bite of an infected: MCQ with Answer and Explanation

Explanation:
The alveoli are the terminal, microscopic, thin-walled, highly vascularized air sacs in the lungs. They are the primary and actual sites of gas exchange, where oxygen diffuses from the inhaled air into the blood, and carbon dioxide diffuses from the blood into the alveolar air to be exhaled. Their large surface area and thin walls facilitate this diffusion.

Explanation:
A synapse is the junction where a nerve impulse is transmitted from one neuron to another. The synaptic cleft is the microscopic, fluid-filled gap between the presynaptic neuron (axon terminal) and the postsynaptic neuron (dendrite or cell body). Neurotransmitters are released into this cleft to carry the signal across to the next cell.

Explanation:
Viruses are non-living outside a host cell and cannot carry out metabolism or reproduce independently. They hijack the host cell's machinery to replicate. Hence they are obligate intracellular parasites. The reason correctly explains the assertion. Even though some debate exists on whether viruses are living, the statement that they are obligate parasites and lack metabolic machinery is accurate.