Answer:
It is called the S-A node, or rather sinus node.
Answer:
the answer is B.)black hole
Explanation:
The defining characteristic of the intertidal zone is that it is submerged with water during high tide and exposed to the air during low tide. The zone can take many forms, from sandy beaches to rocky cliffs. It is common for the intertidal zone to change frequently, since it is constantly battered by crashing waves.
Hope this helped.
Cell membrane allows some material to pass through it while on the same time it blocks other material from entering through it
