Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall
They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season. Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species? A) They must have strong postzygotic isolating mechanisms to spend winter in such close proximity.
B) They must have strong prezygotic isolating mechanisms to spend winter in such close proximity.
C) Their winter habitat has no bearing on their degree of reproductive isolation.
D) Reinforcement must be occurring when they winter together.
C
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Most likely, immunology got its start in 1890 when these scientists discovered antibodies while developing a diphtheria antitoxin.
A) Edward Jenner and Louis Pasteur B) Elie Metchnikoff and Robert Koch C) Emil Behring and Kitasato Shibasaburo D) Jonas Salk and Albert Sabin
Some bacteria in the deep oceans use iron as an
energy source to make carbohydrates from carbon dioxide. These bacteria would be classified as
a. chemoautotrophs. b. chemoheterotrophs. c. photoautotrophs. d. photoheterotrophs. e. decomposers
An artificial pacemaker supplements the actions of
a. sympathetic neurons. b. the atrioventricular node. c. the medulla oblongata. d. the sinoatrial node. e. the heart muscle itself
You ask the butcher to grind a sirloin roast to be used for hamburger. You family likes hamburgers rare, so you undercook the meat. Unfortunately, within 2 days they develop the symptoms of gastrointestinal disease: diarrhea, bloating, and vomiting. Which of the following statements best describes what happened?
A. The meat grinder was contaminated, and bacteria were transferred and distributed throughout the meat. B. The meat became contaminated by bacteria from other foods in your refrigerator. C. The meat became contaminated by bacteria on the barbeque grill, coating both sides of the hamburger patties. D. The animal was sick before slaughter, and the sirloin was contaminated.