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. 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.
Therefore, the Correct Answer is B.
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: Experiments cannot validate hypotheses, only falsify them. The statement above can be restated in which of the following ways?
A. a. Until disproved, an explanation for an observation is valid.
B. b. Certain concepts cannot be subjected to direct experimentation.
C. c. A hypothesis that has not been falsified remains provisional.
D. d. Proving a hypothesis exempts it from further testing
Answer Explanation
The statement "Experiments cannot validate hypotheses, only falsify them" can be restated as "A hypothesis that has not been falsified remains provisional." This means that a hypothesis is considered valid until it is disproved by experimental evidence. However, even if a hypothesis has not been falsified, it is still considered provisional and subject to further testing and scrutiny.
a."Until disproved, an explanation for an observation is valid" is similar to the correct answer but does not capture the provisional nature of a hypothesis.
b."Certain concepts cannot be subjected to direct experimentation" is not a restatement of the original statement.
d. "Proving a hypothesis exempts it from further testing" is incorrect because no hypothesis can be definitively proven and all hypotheses are subject to further testing and scrutiny.
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Q #3: Which of the following actions allows for repolarization of a neuron?
A. The inhibition of sodium and potassium pumps, stopping all ion movement into the neuron
B. The opening of sodium channels, allowing sodium to enter the neuron
C. The closing of both sodium and potassium channels to restrict movement of ions into and out of the neuron
D. The opening of potassium channels allowing potassium to leave the neuron
Answer Explanation
D. The opening of potassium channels allowing potassium to leave the neuron
The correct answer is d. The opening of potassium channels allowing potassium to leave the neuron. Repolarization of a neuron occurs after an action potential, when the neuron's membrane potential returns to its resting state. This is achieved by the opening of potassium channels, which allows potassium ions to flow out of the neuron. This movement of positively charged ions out of the neuron helps to restore the negative membrane potential.
A. The inhibition of sodium and potassium pumps would not allow for repolarization because these pumps are necessary for maintaining the resting membrane potential.
B. The opening of sodium channels would cause depolarization, not repolarization.
C. The closing of both sodium and potassium channels would restrict ion movement, but it would not allow for repolarization.
