Many studies on genetic variation in humans have been done with the perception of taste. The chemical phenylthiocarbamide (PTC) has been used extensively in these studies
Although many individuals cannot taste PTC, many individuals find the taste of PTC to be ________. A) umami
B) salty
C) sour
D) bitter
E) sweet
D
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Which of the following statements is true regarding the experiment described in the text to investigate plant communication via volatile chemicals?
A. The investigators found that volatile chemicals released from damaged plant tissues attract predators but do not affect neighboring plants. B. The experimental plants were exposed to air that had passed through a chamber containing plants with simulated herbivore damage. C. The investigators were testing the hypothesis that volatile chemicals released from plants attract herbivore predators. D. The investigators found that only the damaged plants contained elevated levels of defensive compounds in their leaves when compared with control plants. E. The investigators disproved the hypothesis that some plants "eavesdrop" on their neighbors' defense responses.
Multicellular organisms likely arose around ____ million years ago
a. 900
b. 600 c. 300 d. 100 e. 10
Pigment can be found in several layers of the epidermis. In which layers would you expect to find the cells that produce melanin?
a. stratum granulosum b. stratum lucidum c. stratum basale d. stratum spinosum
Linus Pauling proposed the one gene – one enzyme hypothesis. Indicate whether the statement is true or false