Between the sides of the DNA double helix and teeth of the DNA double helix.

they float because they are less dense than the water itself

something denser than water, like a rock, will sink to the bottom

relative humidity, temperature and dew point -- are bound together in the mathematical relationship below. relative humidity changes when temperatures change. because warm air can hold more water vapor than cool air, relative humidity falls when the temperature rises if no moisture is added to the air. so i would say a

more words for this could be abiotic and biotic

abiotic: living organisms within an ecosystem

biotic: non-living organisms within an ecosystem