Unlike most animals, humans engage in sexual intercourse for pleasure as much or more than for the ...

 It is possible, but intercourse would be more difficult and possibly painful for one or both partners. In men, arousal generally leads to changes in blood flow within the penis that ultimately result in erection of the penis. If an erection failed to occur, smooth muscle contraction would still be necessary to allow sperm release into the vagina. Similarly, women do not need to be aroused to engage in intercourse or for fertilization to occur. However, arousal leads to the release of lubricants in the vagina and surrounding areas that decrease friction during movement of the penis.

Exactly what I needed for my quiz