________ play important roles in maintaining the blood-brain barrier.
A. nodes of Renvier
B. oligodendrocytes
C. microglia
D. astrocytes
Answer: D. astrocytes
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You are a forester charged with increasing productivity in a South American forest newly planted with pines from Oregon
You believe that the southern forest lacks the fungal diversity needed by the North American pines, and that this lack of fungi is affecting the pines' productivity, but you have no evidence to support your ideas. To count how many fungal species were present in the Oregon forest, which methodology would you choose? A) Count all the plant species and multiply by six, as David Hawksworth did when determining the ratio of fungal to plant species in England. B) Collect all the fruiting structures (mushrooms, morels, etc.) found above ground. C) Do direct sequencing on representative soil samples from across the forest. D) Expose the trees to radiolabeled carbon dioxide and then collect the soil samples with the greatest radioactivity and do direct sequencing.
The ____ regulates the movement of food into the stomach and the ____ regulates the passage of food into the small
intestine.
a. epiglottis; gastroesophageal sphincter b. epiglottis; pyloric sphincter c. gastroesophageal sphincter; epiglottis d. gastroesophageal sphincter; pyloric sphincter e. pyloric sphincter; anal sphincter
Oxygen released by ____ accumulated in early Earth's atmosphere and produced the ozone layer
a. early eukaryotes b. cyanobacteria c. archaeans d. protocells e. aerobic bacteria
How does the spread of viruses differ between plants and animals?
A. Viruses must penetrate through cell walls of plant cells and not animal cells. B. Viruses spread faster in plants than animals because of photosynthesis. C. Viruses do not spread to plants, only animals. D. Viruses spread more slowly in plants than animals because of photosynthesis.