Answer:
A. 0.038 g.
Explanation:
- The decay of carbon-14 is a first order reaction.
- The rate constant of the reaction (k) in a first order reaction = ln (2)/half-life = 0.693/(5730 year) = 1.21 x 10⁻⁴ year⁻¹.
<u><em>The integration law of a first order reaction is:</em></u>
<em>kt = ln [Ao]/[A]</em>
k is the rate constant = 1.21 x 10⁻⁴ year⁻¹.
t is the time = 17,190 years.
[Ao] is the initial concentration of carbon-14 = 0.300 g.
[A] is the remaining concentration of carbon-14 = ??? g.
∵ kt = ln [Ao]/[A]
∴ (1.21 x 10⁻⁴ year⁻¹)(17,190 years) = ln (0.300 g)/[A]
2.08 = ln (0.300 g)/[A]
Taking exponential for both sides:
8.0 = (0.300 g)/[A]
<em>∴ [A] = 0.0375 g ≅ 0.038 g</em>
Answer: Extracellular [Ca2+]
Explanation:
The sensitivity and density of the alpha receptors serve to <em>enhance the response to the release of</em> <em>norepinephrine (NE)</em> . However, they do not exert a strong influence as the concentration of calcium ions on the amount of <em>norepinephrine (NE)</em> released by sympathic nerve terminals.
The release of neurotransmitters depends more on either an external or internal stimulus.This results in an action potential which on reaching a nerve terminal, results in the opening of Ca²⁺ channels in the neuronal membrane. Because the extracellular concentration of Ca²⁺ is greater than the intracellular Ca²⁺ concentration, Ca²⁺ flows into the nerve terminal. This triggers a series of events that cause the vesicles containing <em>norepinephrine (NE)</em> to fuse with the plasma membrane and release <em>norepinephrine (NE)</em> into the synapse. The higher the action potential, the higher the Ca²⁺ flow into the terminals resulting in higher amount of <em>norepinephrine (NE)</em> into the synapse, and vice versa.
Catechol-O-methyltransferase (COMT) is one of several enzymes that degrade catecholamines such as dopamine, epinephrine, and norepinephrine. It serves a regulatory purpose to lower the concentration of norepinephrine upon its release from nerve terminals.
The correct answer for this question is D. Define volume, no molecular motion, lowest kinetic energy.
