The answer is Chronic<span> Stress</span>
Once they understood the structure of DNA a lot of things became more clear including how DNA was replicated.
So I think your answer is copies? meaning how it is copied (replicated).
The structure also led later on to how it was transcribed into mRNA (and eventually into proteins by ribosomes).
Blood vessels expand during hot weather and retract/ tighten in cold weather
The immune system works with the digestive tract to help protect you from infection by these potential invaders. Your immune system also depends upon cells to kill invading organisms, and chemicals that don't require the involvement of cells at all, but which are simply toxic to bacteria and viruses. Acid in the stomach does the same thing.
Answer: Permeable
Explanation: In the picture you can see that only the red ones can pass through.
