Answer:
a. A nerve impulse occurs if the excitatory and inhibitory effects are equal.
Explanation:
A nerve impulse occurs when the summation of excitatory postsynaptic potential (EPSPs) from the presynaptic neurons is enough to reach the threshold level.
The excitatory effect of neurotransmitters causes depolarization of the postsynaptic membrane and brings it closer to the threshold to support nerve impulse.
On the other hand, the inhibitory graded potential causes hyperpolarization of the postsynaptic membrane and takes it closer to the resting stage. Hence, excitatory potential should be greater than the inhibitory potential to facilitate the nerve impulse.
The flowchart will be as follows:
Plant shoot is exposed on one side, but not the other side. Then, phototropins in the shoot tip will absorb the blue light. Auxin, a plant hormone, will be released asymmetrically at the tip of the shoot. The auxin released from the stimulus will bind to an auxin receptor and activate the proton pump (H+ pump) activity in the cell membrane making the cell wall more acidic. In an acidic environment, a group of proteins called expansins are activated functioning to connect cellulose microfibrils to each other. Water will then enter the cell and increase cell turgor and subsequently expand the cell leading ultimately to the unequal growth of the plant shoot.
The mouse, every other animal is on it's own as soon as it hatches.
Leukocytes
Hope that helped, Good luck! (:<span />