Which of the following functions does the myelin sheath perform for a nerve cell?
A. Insulation
B. Regeneration
C. Sensory perception
D. Nutrition
The myelin sheath is a protective membrane that wraps around parts of certain nerve cells.
Its fatty-protein coating provides protective insulation for your nerve cell like the plastic insulation covering that encases the wires of an electrical cord ².
This allows the electrical impulses to travel quickly and efficiently between one nerve cell and the next. The other options are incorrect because they do not describe the functions of the myelin sheath.
Regeneration, sensory perception, and nutrition are not functions performed by the myelin sheath for a nerve cell.
Therefore, the Correct Answer is A.
More Questions on TEAS 7 Science
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Q #1: Which of the following summarizes a change that takes place as a solid turns to a liquid?
A. Particles have a decrease in mobility.
B. Particles become less ordered.
C. Particles move closer together.
D. Intermolecular forces between particles become stronger.
Answer Explanation
A change that takes place as a solid turns to a liquid is that particles become less ordered ¹. When a solid is heated, its particles gain energy and begin to vibrate more rapidly ². As the temperature increases, the particles gain enough energy to overcome the forces holding them in place and begin to move more freely
². This results in a loss of order as the solid melts and becomes a liquid.
The other options are not correct because they do not accurately describe a change that takes place as a solid turns to a liquid. Particles do not have a decrease in mobility, move closer together, or experience stronger intermolecular forces between them as a solid turns to a liquid.
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Q #2: Genetic information describing the characteristics of an organism is found in which of the following?
A. Nuclei
B. Membranes
C. Cilia
D. Ribosomes
Answer Explanation
The correct answer is a. Nuclei. Genetic information describing the characteristics of an organism is found in the nuclei of its cells. The nucleus contains the organism's DNA, which carries the genetic information that determines its traits.
b. Membranes are structures that surround and enclose cells and organelles, but they do not contain genetic information.
c. Cilia are hair-like structures that protrude from the surface of some cells and are involved in movement, but they do not contain genetic information.
d. Ribosomes are organelles that are involved in protein synthesis, but they do not contain genetic information.
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Q #3: Which of the following properties does soap, an emulsifier, have that make it useful for washing dirt off one’s hands with water?
A. Soap’s dual polar and nonpolar nature helps bond oil and water
B. Soap’s acidity causes grime to precipitate into the water
C. Soap’s enzymatic action helps to dissolve grime into small particles
D. Soap’s rough texture physically scours grime off surfaces
Answer Explanation
The correct answer is a. Soap’s dual polar and nonpolar nature helps bond oil and water. Soap is an emulsifier, which means that it has both polar and nonpolar regions. The polar regions of soap molecules are atracted to water, while the nonpolar regions are atracted to oil and grease. This allows soap to bond with both water and oil, helping to remove dirt and grime from surfaces.
B. Soap’s acidity does not cause grime to precipitate into the water.
C. Soap does not have enzymatic action that helps to dissolve grime into small particles.
D. Soap’s texture does not physically scour grime off surfaces.
