Nitrogen.
Plants cannot use atmospheric nitrogen directly. Nitrogen from the air must be converted into the different form so plants can absorb it. Thus plants need nitrogen-fixing bacteria to convert atmospheric nitrogen into ammonium, which is available for plants to absorb it.
The control center and director of cell activities is the nucleus. The nucleus, which holds all of the DNA, is found at the center of the cell.
It's called a conduit.
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They can be used to contain cellular waste and to isolate materials that may be harmful to the cell.
Answer:
Similarities: both are chemical messengers, both can have (but don't necessarily have) similar structures (made from amino acids), both can be produced by the central nervous system (hypothalamus produces some hormones), certain molecules can act as both hormones and neurotransmitters (example: norepinephrine).
Differences: neurotransmitters are released by neurons across a synaptic gap, have very short distances to travel, and act very quickly on the neighboring cell. Hormones are released by glands and often have to travel longer distances, which means that they are slower-acting. Also, hormones are typically used for regulation (negative feedback) while neurotransmitters are used for stimulation of a neighboring cell.
Explanation: