A controlled experiment is one in which ________
A) there are at least two groups, one differing from the other by two or more variables
B) the experiment is repeated many times to ensure that the results are accurate
C) the experiment proceeds at a slow pace to guarantee that the scientist can carefully observe all reactions and process all experimental data
D) there are at least two groups, one of which does not receive the experimental treatment
D
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Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
What will be an ideal response?
Answer the following statements true (T) or false (F)
1. When Schmidt-Nielsen and his colleagues followed a "pulse" of air through the respiratory system of an ostrich, it took two full cycles of inhalation and exhalation for this pulse to pass through and be exhaled. 2. Chemoreceptors for oxygen normally play the most important role in regulating breathing rate. 3. Smaller mammals typically have higher ventilation rates than large mammals. 4. The shape of the oxygen-hemoglobin dissociation curve is a straight line. 5. Asthma attacks result from contraction of the muscles surrounding the bronchioles.
Research recently revealed that many plant stress hormones have high potential to be developed as anti-cancer agents. In fact, they were shown to induce cell death and inhibit proliferation and migration of several cancer cell types. Which group of compounds in plants is produced in times of mechanical injury stress such as when a tomato plant is being chewed by a caterpillar?
a. oligosaccharins b. gibberellins c. jasmonates d. abscisic acids
The letter B” in the above figure represents its
a. shell. b. mantle. c. gills. d. siphon. e. none of these.