How are the axons of commissural neurons directed to the floor plate of the spinal cord?
a. ephrins repel the axons
b. eph receptors attract the axons
c. netrins and wny inhibitors attract the axons
d. netrins and shh attract the axons

What re the two main phrases of the cell cycle.

2. if someone had the list of traits you provided in question 1, do you think he or she would be able to find you in a group of 1000 people? why or why not? if not, what other information encoded in your genes might distinguish you from the others in the group? what are other traits that are encoded for by dna?

Why do we perceive objects as retaining their brightness under different lighting levels?