What is the principal substance that causes
phototropism in stems or leaves?
a. auxin
b. gibberellin
c. abscisic acid
d. ethylene
e. all of these
A
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Which one of the following is the outer layer of gray matter found in the cerebrum?
A. cerebral cortex B. central sulcus C. limbic system D. temporal lobe
In the Meselson-Stahl experiment, bacterial DNA was labeled completely with heavy nitrogen (15N) and then grown
in the presence of light nitrogen (14N). When only mixed DNA was observed after ONE generation of growth in 14N, what was the conclusion?
a. DNA replication is semiconservative b. DNA replication is conservative c. DNA replication is dispersive d. DNA replication is either semiconservative or dispersive e. DNA replication is either semiconservative or conservative
As you and a friend are entering a chemistry laboratory at your university, you see a sign that states: DANGER-RADIOACTIVE ISOTOPES IN USE. Your friend is an accounting major and has not had any science courses yet. She asks you what a radioactive isotope is and you respond correctly with
A. radioactive isotopes are atoms that are stable and as a result only emit energy if they are exposed to higher temperatures. B. radioactive isotopes are atoms that are unstable and as a result emit energy in a process called radioactive decay. C. radioactive isotopes are atoms that are stable and as a result emit energy in a process called radioactive decay. D. radioactive isotopes are atoms that are unstable but unless actively disturbed by some chemical process will remain intact and pose no problems.
Suppose you have estimated the following regression: Refrigerator Salesi = ?0 + ?1Pricei + Ui. However, when presenting your results, someone in the audience claims your estimate is biased because your sample only contains sales figures for refrigerators that are priced over $300. Their point is:
A. correct. You have a selected sample on the X variable, so your estimate is biased. B. incorrect. You have a selected sample on Y variable, but this does not bias your estimate. C. correct. You have a selected sample on the Y variable, so your estimate is biased. D. incorrect. You have a selected sample on X variable, but this does not bias your estimate.