Why do the veins of the legs require valves in order to function?
What will be an ideal response?
Blood must return against the force of gravity and at low pressure. The muscles of the legs assist the return of blood by squeezing the veins. A valve prevents backflow, forcing the blood to proceed upward toward the heart.
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Metabolic fingerprinting could be used ____
a. to determine the structure of a metabolite b. to compare the metabolic differences between healthy and disease cells c. to decipher the mRNA sequence of a metabolic enzyme d. to identify the sequence of a metabolic gene e. for paternity testing
Synaptic integration means that ____
a. positive or excitatory stimuli produce an excitatory postsynaptic potential b. the positive and negative ions neutralize each other c. excitatory and inhibitory signals are summed in a receiving neuron d. the adjacent neurons interact so that excitatory and inhibitory stimuli cancel each other out e. excitatory signals take precedence over inhibitory signals
__________ is the conversion of grassland or woodland to desertlike conditions. Fill in the blank(s) with the appropriate word(s)
As temperatures continue to rise, the photosynthetic rate reaches a maximum related to
A) the temperature response of rubisco. B) the thickness of the boundary layer. C) soil temperature. D) oxygen availability.