In botany, a stoma is a pore, found in the leaf and stem epidermis that is used for gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells which are responsible for regulating the size of the opening. Hope that helps you out. best way I can put it for ya!
Answer: RNA is a more stable molecule than DNA
Explanation: DNA (deoxyribonucleic acid) is much stable than RNA (ribonucleic acid) for many reasons; Frist of all its because of the double strand of the DNA versus the single-stranded RNA. This is thanks to the Hydrogen bonding between bases since those bondings release free energy that allows the molecule to be provided by more thermodynamic stability.
Also the lack of 2′ OH groups makes DNA more stable since the OH groups are very reactive by themselves. In the DNA sugar molecule there is not a spare OH group that could start reacting on its own. So this is why DNA is immune to chemical reactions, while RNA (having an extra OH group) is more chemically "promiscuous".
Answer:
The important point is that the surface area to the volume ratio gets smaller as the cell gets larger. Thus, if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume.
