What happens when the resting potential reaches threshold voltage?
A) Voltage-gated sodium channels close.
B) Voltage-gated sodium channels open.
C) The sodium-potassium pump is turned on.
D) Resting potassium channels close.
E) Voltage-gated potassium channels open.
B
You might also like to view...
A muscle contraction that results from a single action potential is known as:
A. a twitch. B. tetanus. C. isometric contraction. D. threshold potential.
Consider the transplantation of tissue from a donor to a recipient who has a different HLA type but the same ABO blood type. Why will the recipient be likely to reject a kidney from the donor, but will not reject the blood from the donor?
A. There are no Class II MHC molecules on the red blood cells in the donor blood. B. There are no Class I MHC molecules on the kidney tissue from the donor. C. There are no Class I MHC molecules on the red blood cells in the donor blood. D. There are no ABO antigens on the kidney tissue.
Which of the following is NOT an enzyme?
A) Lactose B) Amylase C) Catalase D) Protease E) Isomerase
Forelimbs form at the junction of the neck and thoracic vertebrae, the position of which is controlled by HoxC-6 genes. Several kinds of vertebrates from different classes are limbless, including limbless lizards, and amphibians known as caecilians. All descended from limbed forms. On the basis of recent research in genetics, what would you conclude about the functioning of their HoxC-6 genes?
A. Their HoxC-6 gene has mutated and serves a different function than in limbed vertebrates. B. The site of expression of their HoxC-6 genes may have moved anteriorly until the level of expression has eliminated the neck region. C. The site of expression of their HoxC-6 genes would be the same as that of limbed vertebrates but is simply turned off early in development. D. The effect of the HoxC-6 gene is masked by another gene that is dominant to it.