Which of the following functions does the myelin sheath perform for a nerve cell?
A. Insulation
B. Regeneration
C. Sensory perception
D. Nutrition
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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 Exam 3
Question 1:
Which of the following ions binds to the troponin complex, initiating the contraction of a muscle?
A. Sodium
B. Potassium
C. Calcium
D. Phosphorus
The Correct Answer is C.When a muscle cell is stimulated by a nerve impulse, calcium ions are released from the sarcoplasmic reticulum into the cytoplasm. The calcium ions bind to the troponin complex, which is a protein that regulates the interaction between actin and myosin filaments. The binding of calcium to troponin causes a conformational change that exposes the binding sites for myosin on the actin filaments. This allows the myosin heads to attach to the actin and pull the filaments past each other, resulting in muscle contraction.
Question 2:
In which of the following regions of the body are the tibia and fibula?
A. Coxal
B. Antecubital
C. Tarsal
D. Crural
The Correct Answer is D.The tibia and fibula are located in the crural region of the body, which is the lower leg between the knee and ankle. The coxal region refers to the hip area, the antecubital region is the front of the elbow, and the tarsal region is the ankle and foot.
Question 3:
Both digestion and absorption happen in which of the following parts of the digestive system?
A. Gallbladder
B. Esophagus
C. Stomach
D. Small intestine
The Correct Answer is D.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.
Question 4:
Use the table below to answer the question.
|
Object |
Mass (g) |
Time of fall (sec) |
|
1 |
5.0 |
2.0 |
|
2 |
5.0 |
1.0 |
|
3 |
30.0 |
0.5 |
|
4 |
35.0 |
1.5 |
Which of the following conclusions is supported by the data?
A. Objects A and B will fall at the same rate.
B. The greater the mass of an object, the faster it will fall.
C. The time of fall is independent of the mass of the object.
D. Air resistance could be greater for A than for B.
The Correct Answer is D.Question 5:
Which of the following tools can be used to measure the turbidity of a liquid by measuring the transmission of light through the sample?
A. Centrifuge
B. Spectrophotometer
C. Microdensitometer
D. Electrophorometer
The Correct Answer is B.The correct answer is b. Spectrophotometer. A spectrophotometer is a tool that can be used to measure the turbidity of a liquid by measuring the transmission of light through the sample. Turbidity is a measure of the cloudiness or haziness of a liquid caused by the presence of suspended particles. A spectrophotometer measures the amount of light that passes through the sample and compares it to the amount of light that passes through a reference sample to determine the turbidity.
a. A centrifuge is a tool used to separate components of a mixture based on their densities, not to measure
turbidity.
c. A microdensitometer is a tool used to measure the optical density of an image, not to measure turbidity.
d. An electrophorometer is a tool used to separate charged particles based on their size and charge, not to measure turbidity.
Question 6:
Hikers who found a human body at high altitude in the Italian Alps thought the man had died recently, but tests indicated he was shot with an arrow more than 5,300 years ago. Which of the following would be the best reason for prolonged preservation of the body?
A. The ultraviolet rays at such a high altitude caused all his molecules to be preserved.
B. The food that the person ate contained toxins that killed the bacteria that would have otherwise destroyed the body.
C. The body was frozen in the cold temperature of the Alps shortly after he died and remained frozen until it was found.
D. The arrow wound caused blood to flow out of the body which led the enzymes that would break down tissue to be cleared from the body.
The Correct Answer is C.The best reason for the prolonged preservation of the body is that it was frozen in the cold temperature of the Alps shortly after death and remained frozen until it was found. Freezing can preserve a body by slowing down or stopping the decomposition process.
The other options are not as likely to have caused prolonged preservation.
Ultraviolet rays can damage molecules rather than preserve them. Toxins in food would not necessarily kill all bacteria that could cause decomposition. Blood loss from an arrow wound would not necessarily clear all enzymes that could break down tissue.
Question 7:
The triple point of a substance is the temperature and pressure at which the substance exists as which of the following?
A. Simultaneously in sol, gel, and plasma phases
B. As a gel with solid and liquid trapped in gas
C. As a sol with gas and solid trapped in liquid
D. Simultaneously in solid, liquid, and gas phases
The Correct Answer is D.The triple point of a substance is the temperature and pressure at which the substance exists simultaneously in solid, liquid, and gas phases ¹. In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.
The other options are not correct because they do not accurately describe the triple point of a substance. Sol, gel, and plasma are not phases that coexist at the triple.
Question 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
The Correct Answer is C.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.
Question 9:
Which of the following substances is excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia?
A. Lysozymes
B. Urea
C. Water
D. Sebum
The Correct Answer is B.Urea is a waste product that is formed when proteins are broken down in the body. It is excreted by the kidneys in urine, but small amounts can also be excreted by sweat glands in sweat.
The other options are not substances that are excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia. Lysozymes are enzymes that break down bacterial cell walls, water is a component of sweat but is not specifically related to protein breakdown, and sebum is an oily substance produced by sebaceous glands to lubricate the skin.
Question 10:
Parasitic worm infestation is hypothesized to be damaging to the host. However, scientists have recently discovered that worm infestation can relieve the effects of certain autoimmune disorders. In which of the following ways should the hypothesis be modified, given the new findings?
A. Worm infestation prevents the body from immune malfunction.
B. Worm infestation reduces the severity of certain autoimmune disorders.
C. Lack of worm infestations is the cause of some autoimmune disorders.
D. Worm infestations exacerbate the body's immune reaction.
The Correct Answer is B.Given the new findings that worm infestation can relieve the effects of certain autoimmune disorders, the hypothesis should be modified to state that worm infestation reduces the severity of certain autoimmune disorders.
This option best reflects the new information and suggests a potential benefit of worm infestation in relation to autoimmune disorders. The other options do not accurately reflect the new findings and do not provide a clear modification to the hypothesis.