What is the approximate ratio of on-center bipolar cells to off-center bipolar cells in the human retina?
a. 1:1
b. 2:1
c. 5:1
d. 10:1
Question 2
As ________, snakes help to maintain their body temperature by ________.
a. ectotherms; shivering and moving to a warm spot if it is too cold
b. endotherms; shivering and trying to find a warm spot if it is too cold
c. ectotherms; moving to a shady spot if it is too hot
d. endotherms; moving to a shady spot if it is too hot
