Multiple ________ send combined messages to a bipolar cell, whereas a single ________ may link directly to a single bipolar cell.

____ are two possible causes for the higher rates of infertility in countries found in Africa

a. Malnutrition and sexually transmitted infections b. Warmer climate and higher levels of libido c. Religious attitude on sexuality and encouragement of larger families d. Poor sanitation and dietary habits

In which of the following types of research is the researcher most concerned with the representativeness of the sample used?

a. naturalistic observation b. archival analysis c. survey research d. experiments