Surface water always flows downhill. The answer is A.downhill
The three main parts of RNA nucleotide are:
- A nitrogenous base
- A pentose sugar and
- One or more phosphate groups.
Some of the carbon atoms in the glucose exit the leaf as carbon dioxide during respiration while other carbon atoms are used to make important parts of the plant, such as additional leaves or wood. Carbon atoms that remain in leaves will either fall off (during plant senescence) or become a meal for an animal. Hope this helps
A signal cascade is a series of chemical reactions which are triggered by a stimulus acting on a receptor that is then transduced to the intracellular space through second messengers. Finally, effector molecules receive the signal causing a cellular reaction to the initial stimulus. A signal cascade is very useful because it facilitates and accelerates the communication between cells that could be in different parts of a living organism. This communication is vital for cell processes in complex multicellular organisms.