Which of the following does not influence the time necessary for a nerve impulse to be transmitted?
a. length of the axon
b. presence or absence of a myelin sheath
c. diameter of the axon
d. presence or absence of nodes
e. whether or not the impulse begins in the cns

e. whether or not the impulse begins in the CNS

Explanation:

Nerve impulse is action potential movement through the axon. Nerve impulse propagation has its velocity (speed at which nerve impulse travels down the axon) which depends on many factors. For example, myelination increases the conduction velocity. Also, the larger the diameter of an axon, the higher the velocity is. Nodes of Ranvier present on the axons, and myelin sheath between the nodes act as a good electrical insulator which also increases the velocity.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."

what school and grade?