A mechanism in which two substances move in opposite directions across the cell membrane is called
A) facilitated diffusion.
B) vesicular transport.
C) endocytosis.
D) countertransport.
E) osmosis.
D) countertransport.
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In craniosynostosis, the bones of the skull fuse together at the sutures prematurely, causing the brain to grow abnormally. Why would this cause abnormal brain growth?
A. The sutures are amphiarthrotic and slightly move during brain growth, so the plates of the skull can easily move to suit any direction of brain growth. Fusion at the sutures will prevent this free movement. B. The sutures are synarthrotic and do not move, only allowing expansion from within as the brain grows to fill the brain case. Fusion at the sutures will prevent this expansion. C. Because the sutures contain ligaments, blows to the skull can be absorbed by plate movement. Removal of the sutures will cause any slight blow to damage the brain. D. Sutures are large gaps between bones that are filled with synovial fluid. This synovial fluid allows for the brain to expand into the spaces. Ossification of the sutures would prevent the expansion of the brain.
Old discs shed from rods and cones are phagocytosed by
A) the outer segment. B) the inner segment. C) the pigment epithelium. D) the bipolar cells. E) the ganglion cells.
Chromosomes are shaped like the letter Z
Indicate whether the statement is true or false
The upper motor neurons that control skeletal muscles begin with a neurosoma in the ________.
A. motor association cortex of the cerebrum B. anterior horn of the spinal cord C. precentral gyrus of the cerebrum D. posterior horn of the spinal cord E. postcentral gyrus of the cerebrum