Answer:
Yes. Cells have 'cell receptors' that are used to receive messengers like hormones to communicate. Cell receptors have specific shapes that fit the shape of the messenger that they want to receive. Organs like the pancreas send our these messengers to the cells to order them to do different functions.
Can you be more specific with the question. Are you talking about DNA coding with complementary bases?
I believe there has to be enough activation energy for a reaction to occur in the first place, if that is what you are referencing
Answer:
The pressure differences on either side of the valve.
Explanation:
The heart valves open and close passively because of pressure differences on either side of the valve. When pressure is greater behind the valve, the leaflets are blown open and the blood flows through the valve. However, when pressure is greater in front of the valve, the leaflets snap shut and blood flow is stopped.
Hope this helps!
have a blessed day
What sample are you talking about?