In mammals, The placenta is essential to the embryo for:

A. Nutrition, reproduction, and growth
B. Nutrition, respiration, and excretion
C. Locomotion, respiration, and excretion
D. Nutrition, reproduction, and excretion

Which of the following substances is not involved in the chemical reaction that pro- duces smog? a. sunlight b. particulate matter c. automotive exhaust d. ozone

Which of these organisms have the greatest amount of cell specialized

Next pretest: evolution select the correct answer in a laboratory population of flies, the female flies are gray and the males are yellowish gray. biologists observed that all the male flies had an equal chance for reproduction, but the male flies with the brightest colors were more likely to successfully reproduce. what phenomenon could explain such a change? a sexual selection b. disruptive selection c. stabilizing selection d. directional selection