During the initiation of nitrogen-fixation nodules, how do the Rhizobium bacteria enter into the cortex of the root?
A. through the plasmadesmata of the root hairs
B. via the apoplastic pathway
C. using proton pumps
D. through a membrane tube called an infection thread
E. by repeated cell divisions
D. through a membrane tube called an infection thread
In the process of root nodule formation, the root hair grows and curls around the bacteria. The bacteria then initiate an infection thread which in an entryway for the bacteria into the root.
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Chemical energy is most often released by ________.
A. adding phosphate groups to a molecule B. creating a bond between two molecules C. breaking a bond within a molecule D. reorganizing molecules with each other
The human immune system consists of
A) about 10,000 cells that increase rapidly to trillions when an infection takes hold. B) the heart and blood vessels and the blood cells within the vessels. C) about 2 trillion cells, their secretions, and the organs where they are produced and stored. D) all of the bacteria and viruses that are normally present in our bodies plus our blood cells.
Ivan Valiela's hypothesis that the growth of salt marsh grass is limited by nitrogen availability was:
a. disproved by the growth of larger and taller grass in his control (nitrogen-fertilized) plots. b. disproved by the growth of larger and taller grass in his experimental (nitrogen-fertilized) plots. c. supported by the growth of larger and taller grass in his experimental (nitrogen-fertilized) plots. d. supported by the growth of larger and taller grass in his control (nitrogen-fertilized) plots. e. unsupported by a poor experimental design.
What is the purpose of using bacteria to study the function of myoglobin?
a. Bacterial myoglobin is similar to mammal myoglobin. b. Bacteria genes are easier to clone than mammal genes. c. Bacteria can express a myoglobin gene and myoglobin molecules can be produced in quantity. d. Bacterial reproduction rates. e. Rates of evolutionary change in bacteria.