All isotopes of an element have a different number of ____
a. electrons
b. protons
c. neutrons
d. orbital shells
e. atoms
ANSWER: c
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Humans cannot survive at sea by drinking salt water. However, marine vertebrates such as sea turtles and various sea birds can survive by drinking salt water. What do they have that humans do not?
A. kidneys that are extremely good at producing a concentrated urine. B. body fluid concentrations that are similar to or greater than those of seawater. C. the ability to secrete salts and wastes into their intestinal contents like an insect. D. They use ammonia as their primary nitrogenous waste. E. salt glands.
Match the following items with the correct phrases.
_______1. Testes _______2. Throat _______3. Brain _______4. Kidney _______5. Spinal cord A) Encephalitis B) Myelitis C) Nephritis D) Orchitis E) Pharyngitis
The nitrogen-limitation hypothesis states that organisms select food in terms of the nitrogen content of the tissue. Why might this be true?
A. Because many consumers need large amounts of nitrogen; for example, animal tissue contains about 10 times as much nitrogen as plant tissue. B. Because most organisms are able to "fix" nitrogen more efficiently than plants. C. Because foods with lower nitrogen content are easier for consumers to digest, leading most organisms to seek out low nitrogen foods. D. Because high nitrogen levels are a key part of plant chemical defenses, resulting in organisms avoiding high nitrogen plants. E. Because plant tissues contain, on average, 10 times the level of nitrogen needed by most consumers.
In a national park in Zambia, the percentage of tuskless female elephants increased from 10% in 1969 to 38% in 1989. What was the direct cause of this increase?
A) illegal poaching by ivory hunters B) fierce competition between male and female elephants for limited food resources C) periodontal disease D) The cause of this increase is unknown.