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: Emphysema caused by damage to alveoli from toxins and pollutants is likely to result in the body having difficulty performing which of the following actions?
A. Releasing histamine and acetylcholine
B. Exchanging oxygen and carbon dioxide
C. Absorbing food
D. Producing enzymes
Answer Explanation
Emphysema is a lung condition that is caused by damage to the alveoli, the tiny air sacs in the lungs where gas exchange occurs. When the alveoli are damaged, the body has difficulty exchanging oxygen and carbon dioxide. This can lead to shortness of breath and other respiratory problems. The other options are not directly related to the function of the alveoli or the effects of emphysema.
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Q #2: Which of the following is the function of a totipotent cell?
A. Develops into any kind of cell
B. Fights infectious diseases
C. Aids in the maturation of sex cells
D. Carries electrical impulses
Answer Explanation
The function of a totipotent cell is to develop into any kind of cell ¹. Totipotent cells have the capacity to produce all adult cell types and can enter the germ line, contributing genetic material to succeeding generations ?. They have the ability to self-replicate, producing daughter cells that are identical to the parent ?.
The other options are incorrect because they do not accurately describe the function of a totipotent cell. Fighting infectious diseases, aiding in the maturation of sex cells, and carrying electrical impulses are not functions performed by totipotent cells.
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Q #3: A researcher wants to gather data on the average wing strength of all birds found in the American Northwest. The researcher only has one small net, so all large birds were excluded from the study. The researcher's results were different than expected, but he believes his data include enough birds to estimate the strength of all birds. For which of the following reasons should this data be rejected?
A. Data contradict the control group
B. Data were different than expected
C. Data are biased by the methodology
D. Data cannot be displayed graphically
Answer Explanation
The correct answer is c. Data are biased by the methodology. The researcher's data should be rejected because they are biased by the methodology used to gather them. By only using a small net, the researcher excluded all large birds from the study. This means that the data do not accurately represent the average wing strength of all birds found in the American Northwest.
A. The data contradicting the control group is not a reason to reject the data in this case.
B. The data being different than expected is not a reason to reject the data in this case.
D. The data not being able to be displayed graphically is not a reason to reject the data in this case.
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Q #4: Which of the following describes a genetic mutation that results in uncontrolled division of a single cell within the body?
A. Cancer
B. Gene therapy
C. Stem cell
D. Translation
Answer Explanation
A genetic mutation that results in uncontrolled division of a single cell within the body describes cancer ¹. Cancer is a disease of uncontrolled cell division ¹. Its development and progression are usually linked to a series of changes in the activity of cell cycle regulators ¹. In most cases, these changes in activity are due to mutations in the genes that encode cell cycle regulator proteins ¹.
The other options are not correct because they do not accurately describe a genetic mutation that results in uncontrolled division of a single cell within the body. Gene therapy, stem cells, and translation are not processes that result in uncontrolled cell division.
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Q #5: Which of the following best describes the result of using a catalyst in a chemical reaction?
A. A more desirable product is often formed.
B. The reaction is completed in a shorter amount of time.
C. A greater amount of heat energy is released by the reaction.
D. The yield of product is increased.
Answer Explanation
The result of using a catalyst in a chemical reaction is that the reaction is completed in a shorter amount of time ¹. A catalyst is a chemical substance that affects the rate of a chemical reaction by altering the activation energy required for the reaction to proceed ¹. This process is called catalysis ¹. A catalyst provides an alternative pathway for the reaction, one that has a lower activation energy than the uncatalyzed pathway .
The other options are not correct because they do not accurately describe the result of using a catalyst in a chemical reaction. A more desirable product is not necessarily formed, a greater amount of heat energy is not necessarily released by the reaction, and the yield of product is not necessarily increased as a result of using a catalyst.
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Q #6: The covalent bonds between the monomers of an enzyme macromolecule are:
A. Ester bonds
B. Peptide bonds
C. Phosphodiester bonds
D. Glycosidic bonds
Answer Explanation
The correct answer is b. Peptide bonds. Enzymes are proteins, and proteins are made up of amino acid monomers linked together by peptide bonds. A peptide bond is a covalent bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid.
a. Ester bonds are covalent bonds that form between a carboxylic acid and an alcohol.
c. Phosphodiester bonds are covalent bonds that form between a phosphate group and two hydroxyl
groups.
d. Glycosidic bonds are covalent bonds that form between two monosaccharides.
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Q #7: Which of the following occurs in an oxidation reaction?
A. Removal of oxygen
B. Addition of carbon
C. Addition of neutrons
D. Removal of electrons
Answer Explanation
An oxidation reaction occurs when there is a removal of electrons ¹. Oxidation is the loss of electrons during a reaction by a molecule, atom or ion ¹. When oxidation occurs, the oxidation state of the chemical species increases ¹.
The other options are not correct because they do not accurately describe what occurs in an oxidation reaction. Removal of oxygen, addition of carbon, and addition of neutrons are not processes that occur in an oxidation reaction.
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Q #8: Which of the following correctly orders structures from simple to complex?
A. Cells, tissues, atoms, organs
B. Atoms, organs, tissues, cells
C. Atoms, cells, tissues, organs
D. Organs, tissues, cells, atoms
Answer Explanation
The correct answer is c. Atoms, cells, tissues, organs. This is the correct order of structures from simple to complex. Atoms are the smallest and simplest units of mater. Cells are made up of atoms and are the basic units of life.
Tissues are groups of similar cells that work together to perform a specific function. Organs are made up of different types of tissues and perform more complex functions.
A. Cells, tissues, atoms, organs is not the correct order from simple to complex.
B. Atoms, organs, tissues, cells is not the correct order from simple to complex.
D. Organs, tissues, cells, atoms is not the correct order from simple to complex.
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Q #9: Punnet Square An organism with an unknown genotype is crossed with another organism that shows the recessive trait (aa). The Punnet square below shows the results. Which of the following is the unknown genotype? Unknown Unkonwn a Aa aa a Aa aa
A. a
B. Aa
C. aa
D. AA
Answer Explanation
The unknown genotype is Aa. This can be inferred from the Punnet square, which shows that half of the offspring are Aa and half are aa. This indicates that the unknown parent must have one dominant allele (A) and one recessive allele (a), making its genotype Aa.
The other options are not correct because they do not match the results shown in the Punnet square. If the unknown genotype was aa or AA, all of the offspring would have the same genotype as their parent. If the unknown genotype was a, it would not be a valid genotype as it only has one allele.
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Q #10: Both digestion and absorption happen in which of the following parts of the digestive system?
A. Gallbladder
B. Esophagus
C. Stomach
D. Small intestine
Answer Explanation
Both digestion and absorption happen in the small intestine ¹. Digestion is the process by which food is broken down into small molecules that the body can absorb and use for energy, growth, and repair ¹. The final products of digestion are absorbed from the digestive tract, primarily in the small intestine ¹.
The other options are not correct because they do not accurately describe where both digestion and absorption happen in the digestive system. The gallbladder stores bile produced by the liver, but does not play a direct role in digestion or absorption. The esophagus transports food from the mouth to the stomach, but does not play a direct role in digestion or absorption. The stomach plays a role in digestion by churning food and mixing it with gastric juices, but most absorption occurs in the small intestine.
