Consider the Calvin-Benson cycle and the noncyclic photosynthetic pathway. Why is the cyclic pathway so
important?
What will be an ideal response?
ANSWER: The Calvin-Benson cycle uses 18 ATP and 12 NADPH to produce one molecule of glucose.
However, the noncyclic photosynthetic pathway produces ATP and NADPH at a one-to-one
ratio. As a result there would be insufficient ATP. However, the cyclic pathway produces
only ATP, thus allowing light-dependent reactions to continue when the noncyclic pathway
stops.
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The alternate complement pathway plays an important role in
A. innate immunity. B. specific immunity. C. acquired immunity. D. both innate immunity and specific immunity.
Which of the following is (are) true concerning
tetanus? a. The pathogen spreads through the air. b. The pathogen is ingested through tainted canned food. c. The pathogen is a virus. d. Blood or nerves deliver the toxin to the spinal cord and brain. e. All of these are true.
A large number of copies of any DNA segment can be obtained by:
a. introducing foreign DNA into a microorganism so that it can be replicated. b. stimulating increased transcription of the appropriate sequence of mRNA. c. stimulating increased translation of the appropriate DNA molecule. d. inducing the production of DNA from proteins. e. stimulating reverse transcription of tRNA
The outside of a neuron is positively charged at resting potential. Why do K+ ions leave the cell when K+ channels open during an action potential?
A. Negatively charged proteins leave the cell at the onset of the action potential. B. The diffusion gradient is the only factor that affects ion movement. C. K+ ions are actively pumped out by the sodium-potassium pump acting in reverse. D. Voltage-gated K+ channels open when membrane potential reaches +50 mV during the depolarization phase. The diffusion gradient and electrical force cooperate to drive K+ ions out of the cell.