As summer comes to the tundra, what will
occur?
a. A long growing season will begin.
b. The surface layer will thaw and pools of
water will form.
c. The permafrost thaws out.
d. Birds will begin their southerly migration.
e. more than one of these
B
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The diagram shows a generalized cross section of the marine environment with various zones labeled with letters
Which zone has a condition of constant temperature? A) A B) B C) C D) D E) E
Which of the following is the skeletal muscle type associated with stamina and endurance?
A. smooth muscle B. fast twitch fibers C. slow twitch fibers D. isometric motor units
Methicillin-resistant Staphylococcus aureus (MRSA) can be a serious threat to human health. There is evidence that S. aureus infections are common in hospitals and that MRSA have become resistant to other antibiotics besides methicillin. This suggests that the rapid evolution of resistance in the bacteria poses a serious public-health challenge. Which of the following best explains the ability of MRSA to evade existing drug therapies?
(A) MRSA have very long generation times and very large population sizes. (B) MRSA develop new alleles by intentionally introducing specific mutations that will give them a selective advantage over other bacteria. (C) MRSA metabolize many drugs in their lysosomes and therefore evolve resistance at a high rate. (D) MRSA exchange genetic material with other antibiotic-resistant bacteria, which can spread resistance in the S. aureus population.
A solvent is usually a
A. gas B. solid C. liquid