What structures allow water to move laterally and vertically through xylem cells?
a. sieve elements
b. companion cells
c. sclereids in the cell walls
d. pits in the cell walls
e. perforated sieve plates
ANSWER: d
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In humans, which receptor is used primarily to detect light?
A. photoreceptor B. proprioceptor C. chemoreceptor D. mechanoreceptor E. electroreceptor
Matching I. Even though there may be more than one
correct letter response to some numbered items, discriminate and “juggle” so that you have the one BEST response for each blank. 1. ___ effector 2. ___ excitatory postsynaptic potential 3. ___ ganglion 4. ___ integrator 5. ___ Inhibitory Postsynaptic Potential 6. ___ interneuron 7. ___ muscle spindle 8. ___ myelin sheath 9. ___ neuroglia 10. ___ receptor 11. ___ recovery period 12. ___ response 13. ___ sodium-potassium pump 14. ___ stimulus 15. ___ neurotransmitter molecule A. cells that nurture and support neurons B. a hyperpolarizing event C. a neuron cannot propagate an action potential at this time D. ACh or GABA E. interneuron in brain or spinal cord F. establishes basis of resting membrane potential G. sheathed muscle cells that contain receptors H. input I. integrator cell between sensory and motor J. modified dendrite of a sensory neuron K. a depolarizing event L. output M. muscle or gland N. produced by a Schwann cell O. cluster of cell bodies outside the CNS
During protein synthesis, ribosomes:a
attach to the mRNA molecule and travel along its length to produce a polypeptide. b. attach to the DNA molecule and travel along its length to produce an mRNA molecule. c. translate mRNA into tRNA. d. transcribe DNA into mRNA. e. translate tRNA into protein.
By examining fossil evidence, paleontologists believe that mammals evolved from ancestors of modern
A) arthropods. B) amphibians. C) sharks. D) lobefins. E) reptiles.