Which component of a muscle does the calcium ion combine with to allow a contraction to occur?
A) myosin head B) T tubule C) actin D) troponin
Answer: D
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The Calvin cycle of a plant exposed to light during the day that is suddenly put in the dark
A. cannot run, as it requires light energy directly. B. can still run as long as there is ATP, CO2, and NADPH present. C. runs in a different place in the plant. D. uses a different source of carbon.
Fungi spores are haploid; what distinguishes haploid spores?
A. Haploid spores have a double set of chromosomes, half the number of chromosomes of diploid organisms. B. Like diploid organisms, haploid spores have a single set of chromosomes. C. Haploid spores have a single set of chromosomes, half the number of chromosomes of diploid organisms. D. Like diploid organisms, haploid spores have a double set of chromosomes.
What is the main idea behind the model of a molecular clock?
a. that neutral mutations accumulate at a steady rate b. that certain traits are under the pressure of natural selection c. that segments of DNA can be compared with segments of RNA d. that phenotypes, not genotypes, are affected by natural selection
The protozoan that causes malaria is an intracellular parasite of red blood cells (RBCs). An adaptive immune response to this parasite is problematic because
A. red blood cells do not produce MHC and, therefore, do not display the fact that they have been infected by presenting antigen. B. the parasite damages leukocytes along with RBCs. C. RBCs normally produce cytokines necessary for adaptive immune response, which this infection prevents. D. complement cannot effectively destroy RBCs. E. RBCs never enter lymphoid tissue.