I think mRNA is produced in the nucleus
The cell membrane is said to be selectively permeable is because it allows a select few things to go through while stopping the passage of other stuff.
I believe a pot of water that is being heated by a electric burner. This is because the warmer water moves to the top and the cooler water moves down to the bottom of the pot. This causes a circular motion. The next example of convection heat is a hot air ballon rising and falling in the atmosphere. A radiator is also because the hot air is drawn out the top and the cooler air is drawn to the bottom.
<span>Essentially, cohesion and adhesion are the "stickiness" that water molecules have for each other and for other substances. You can see this in the picture to the right. The water drop is composed of water molecules that like to stick together, an example of the property of cohesion.</span>