1) A paper towel is to its cardboard roll as the myelin sheath is to the________
ID: 50569 • Letter: 1
Question
1) A paper towel is to its cardboard roll as the myelin sheath is to the_______________ .
soma
dendrite
Schwann cell
axon
2) When the membrane of an axon is at resting potential, which of the following is true?
The exterior of the cell has a net negative charge and the interior has a net positive charge.
The exterior of the cell has a net negative charge and the interior is neutral.
The exterior of the cell has a net positive charge and the interior has a net negative charge
The exterior of the cell has a net positive charge and the interior is neutral.
3) A man standing in a park is talking to a friend 3 feet away and then turns to look at a dog 50 yards away. How does the eye adapt to allow him to clearly see these two different images?
The lens is moved backward
The lens is moved forward.
4) Pepsin is a digestive enzyme. It is made in an inactive form, pepsinogen, which is activated by the acidity of the stomach to self-cleave (cut itself) into a formed called the cleaved molecule. This cleaved molecule is active pepsin, which goes on to cleave more pepsinogen molecules, leading to a cascade of rapid pepsin activation (and many more active pepsin molecules). This pathway is an example of:
a feedforward regulation
a positive feedback loop
a negative feedback loop
conditioning
soma
dendrite
Schwann cell
axon
Explanation / Answer
1. axon , ---- axon is a part of nerve fibre which is covered with a myylein sheath , those are called myleinated neurons , it helps in insulation.
2. The exterior of the cell has a net positive charge and the interior has a net negative charge ---- the resting potential in nerve cell is -70mV , which means inside of the cell is at a negative potential relative to external medium
3. The ciliary muscles relax and the lens becomes more flat.------ ciliary muscles helps to change the size of the lens and thereby its focal length for a distant object to be seen , the curvature of the lens decreases thereby increasing its focal length.
ans 4 --- a positive feedback loop
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