A red blood cell contains a large nucleus; it is thicker near the center and thin around the rim of the cell:
False
True.
The Correct Answer is A
Red blood cells do not contain a large nucleus; in fact, they do not contain a nucleus at all when they are mature.
This is an adaptation that allows them to carry more hemoglobin, the protein that binds oxygen, and to squeeze through narrow capillaries.
Choice B is wrong because it contradicts the fact that red blood cells are enucleated (lacking a nucleus) in humans and most mammals.
Some vertebrates, such as birds and fish, have nucleated red blood cells, but they are not thick near the center and thin around the rim of the cell.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The correct answer is choice A. True.
Blood flow through a capillary is controlled by a precapillary sphincter, which opens or closes due to the requirements of the cells supplied by the capillary.
This allows blood to bypass the capillaries when they are not needed and to increase blood flow when they are needed.
Choice B. False is wrong because it contradicts the true statement in choice A. A precapillary sphincter is a ring of smooth muscle that surrounds the entrance of a capillary and regulates blood flow into it.
It is influenced by local factors such as oxygen, carbon dioxide, pH, and temperature.
Correct Answer is C
Explanation
A newborn is protected against certain digestive and respiratory infections by IgA received via the mother’s milk.
IgA is the main antibody found in breast milk, and it coats and seals the baby’s respiratory and intestinal tract to prevent germs from entering the body and bloodstream.
Choice A is wrong because the blood does not contain IgA, which is the main antibody that protects mucosal membranes.
Choice B is wrong because the placenta does not transfer IgA to the fetus, but only some other antibodies such as IgG.
Choice D is wrong because the intestine does not produce IgA in newborns, as they are born with low levels of IgA.
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