The chemoreceptors of the tongue respond to monosaccharides (sugars), metal ions (salty tastes), alkaloids, and acids. which type of receptor do you think is the most sensitive? why?

The alkaloids refer to the toxin generated by the plants. They give greater sensitivity and are bitter in taste. The tongue comprises unique receptors for bitter taste at its back. When one taste something toxic or bad then the neurons of tongue transmit signals to the brain and the brain provides reaction that whether it is bad or good for the body to consume. The substances, which are bitter instigate the generation of IP3 from the taste cells. This further enhances the intracellular calcium levels that results in the discharging of the synaptic transmitter and the stimulation of the gustatory nerve fibers.

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.