Answer:
the paired bases( nitrogenous bases )
Lets consider the water drop as being part of the water in a lake. The water droplet evaporates and changes from a liquid state to a vapor state by gaining energy and travels up to the upper atmosphere. In the atmosphere the water droplet once again condenses in the clouds and is stored until it can be precipitated on to the land again in the form of rain or other forms of precipitation.
For centuries, many scientists hypothesized that birds were reptiles due to similarities in their anatomy, but there was no hard fossil evidence to support it. But in 1860, archaeologists discovered a fossil of a highly detailed Archaropteryx lithographica (a bird-like dinosaur), which filled the void of the “transitional species” that scientists needed to link birds and reptiles. Since then, many fossils of feathered dinosaurs have been found.
The reason they don't tan is because their melanocytes are inactive.
Hope this helps<3
