Old cultures of bacteria that have lost their ability to cause disease are said to be
A. pathogenic.
B. impotent.
C. attenuated.
D. virulent.
Answer: C
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Water has an unusually high boiling point for its molecular weight because water molecules ____
a. are very dense b. get much heavier as they are heated c. are held to each other by hydrogen bonds d. are held together by covalent bonds e. form hydration layers
Which of the following best describes the endosymbiotic theory?
a. Aerobic respiration is more efficient than anaerobic respiration. b. Prokaryotes evolved to live side by side with eukaryotes. c. Eukaryotes are the result of one prokaryotic cell engulfing another. d. Mitochondria can only live inside a eukaryotic cell.
We use the scientific method every day. Imagine that your car doesn't start one morning before school. Which of these is a reasonable hypothesis regarding the problem?
A) If I put gas in my car, it will start. B) I'm going to be late. C) I should add a quart of oil. D) I should check whether the lights were left on and drained the battery. E) I should change the battery or the starter.
What is not a method used by ectotherms to affect body temperature?
A. Countercurrent heat exchange B. Shivering C. Basking in the sun D. Increasing metabolic rate E. Dilation or contraction of blood vessels in skin