In the late 1870s, Charles Darwin and his son, Francis, discovered that if the tip of the grass was covered, phototropism did not occur, even though the rest of the grass was exposed to light. However, if the rest of the plant was covered and only the tip exposed to light, the grass bent a few centimeters below the tip. Which of the following was sensing the light?
A. auxin-detecting cells in the tip of the grass
B. auxin-producing cells in the tip of the grass
C. auxin-producing cells a few centimeters below the tip of the grass
D. auxin-detecting cells a few centimeters below the tip of the grass
B. auxin-producing cells in the tip of the grass
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Molecules assisted by carrier proteins may cross a selectively permeable membrane by
A) facilitated diffusion. B) active transport. C) osmosis. D) simple diffusion. E) endocytosis.
The structure at the tip of the red arrow is the ______ ______ of this enzyme.
Fill in the blank(s) with the appropriate word(s).
All of the following are correct about the indirect ELISA, except
A.) it can detect antibodies in a serum sample. B.) it is the common screening test for antibodies to Helicobacter. C.) color development indicates that antibody was not present in the patient's serum. D.) it is the common screening test for antibodies to Hepatitis A. E.) a known antigen is adsorbed to the surface of a well.
In a neutral atom, the number of protons are equal to the number of:
A. ions B. electrons C. the atomic mass D. neutrons