1. natural selection acts on existing traits because you can not evolve into something you didn't have
2. original structures evolve to accomplish new function in order to survive
Answer: Ribose nucleotides and the nitrogenous bases
Explanation: RNA consists of ribose nucleotides (nitrogenous bases appended to a ribose sugar) attached by phosphodiester bonds, forming strands of varying lengths. The nitrogenous bases in RNA are adenine, guanine, cytosine, and uracil, which replaces thymine in DNA.
I hope this helps you!! :)
The fluid inside of the Extracellular Matrix is Extracellular Fluid. Extracellular Fluid is also called ECF. ECF is mostly tissue fluid. It is also made up of a large amount of intravascular fluid. The remaining smaller amount of ECF is transcellular fluid.
hope i could help :)