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: Which of the following terms describes the relaxation of the chambers of the heart during the cardiac cycle?
A. Tachycardia
B. Diastole
C. Systole
D. Bradycardia
Answer Explanation
The relaxation of the chambers of the heart during the cardiac cycle is called diastole ¹. The cardiac cycle is a sequence of events that occurs when the heart beats ². It consists of two phases: systole, when the heart contracts and pumps blood into circulation, and diastole, when the heart relaxes and fills with blood ².
The other options are not correct because they do not accurately describe the relaxation of the chambers of the heart during the cardiac cycle. Tachycardia is a rapid heart rate, bradycardia is a slow heart rate, and systole is the contraction of the heart chambers.
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Q #2: Which of the following substances is responsible for donating H+ ions to act as a buffer when blood pH rises?
A. Oxygen
B. Carbon monoxide
C. Carbon dioxide
D. Carbonic acid
Answer Explanation
The correct answer is d. Carbonic acid. When blood pH rises, carbonic acid can donate H+ ions to act as a buffer and help maintain the pH within a normal range. Carbonic acid is formed when carbon dioxide dissolves in water and reacts with it.
A. Oxygen is not responsible for donating H+ ions to act as a buffer when blood pH rises.
B. Carbon monoxide is a toxic gas that does not play a role in buffering blood pH.
C. Carbon dioxide can dissolve in water to form carbonic acid, which can then donate H+ ions to act as a buffer.
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Q #3: 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 #4: 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 #5: The mitochondrial inner membrane carries out the same function in cellular respiration as the ________ membrane of chloroplasts in photosynthesis. Which of the following correctly completes the sentence above?
A. Thylakoid
B. Epithelial
C. Nuclear
D. Tonoplast
Answer Explanation
The thylakoid membrane of chloroplasts is where the light-dependent reactions of photosynthesis take place, while the mitochondrial inner membrane is where the electron transport chain and ATP synthesis occur during cellular respiration.
The tonoplast is the membrane that surrounds the central vacuole in plant cells. It is not involved in cellular respiration or photosynthesis.
The other options, epithelial and nuclear, are not related to these processes.
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Q #6: How many times stronger is the hydrogen-ion concentration of a pH 4 solution as compared with a pH 9 solution?
A. 0.00001
B. 5
C. 100,000
D. 50
Answer Explanation
The correct answer is c. 100,000. The pH scale is a logarithmic scale, which means that each change of one pH unit represents a tenfold change in the hydrogen-ion concentration. A pH 4 solution has a hydrogen-ion concentration that is 10^5 (or 100,000) times greater than that of a pH 9 solution.
a. 0.00001 is the hydrogen-ion concentration of a pH 9 solution as compared with a pH 4 solution.
b. 5 is the difference in pH units between a pH 4 solution and a pH 9 solution.
d. 50 is not the correct answer.
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Q #7: Which of the following immune system molecules creates holes in the cell membranes of their target cells in order to destroy the cell?
A. Perforins
B. Interferons
C. Cytokines
D. Lymphotoxins
Answer Explanation
Perforins are immune system molecules that create holes in the cell membranes of their target cells in order to destroy the cell. Perforins are proteins that are released by cytotoxic T cells and natural killer cells
They form pores in the target cell membrane, allowing water and ions to enter the cell and causing it to swell and burst.
The other options are not correct because they do not accurately describe the immune system molecules that create holes in the cell membranes of their target cells. Interferons, cytokines, and lymphotoxins do not create holes in cell membranes.
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Q #8: For which of the following reasons does a chloride ion have a negative charge?
A. It gained an electron
B. It lost an electron.
C. It lost a proton.
D. It gained a proton.
Answer Explanation
A chloride ion has a negative charge because it gained an electron. When an atom gains an electron, it becomes negatively charged because it now has more electrons than protons. In the case of a chloride ion, the neutral chlorine atom gains an electron to become a negatively charged chloride ion.
The other options are incorrect because they do not result in a negative charge. Losing an electron would result in a positive charge. Losing or gaining a proton would change the identity of the atom and is not related to the formation of a chloride ion.
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Q #9: An individual suffers severe blunt trauma to the thoracic cavity. Which of the following organs are at greatest risk from this injury?
A. Heart and lungs
B. Brain and spinal cord
C. Liver and stomach
D. Large and small intestines
Answer Explanation
The correct answer is a. Heart and lungs. The thoracic cavity contains the heart and lungs, which are at greatest risk from severe blunt trauma to this area.
a.The brain and spinal cord are not located in the thoracic cavity and are therefore not at greatest risk from blunt trauma to this area.
c.The liver and stomach are located in the abdominal cavity, which is below the thoracic cavity. While these organs may be affected by severe blunt trauma to the thoracic cavity, they are not at greatest risk.
d.The large and small intestines are also located in the abdominal cavity and are not at greatest risk from blunt trauma to the thoracic cavity.
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Q #10: 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.
