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
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.
Therefore, the Correct Answer is C.
More Questions on TEAS 7 Science
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Q #1: Which of the following is a component of the integumentary system that secretes pheromones?
A. Fossa ovalis
B. Seminiferous tubule
C. Dermal papilla
D. Apocrine gland
Answer Explanation
The apocrine gland is a component of the integumentary system that secretes pheromones. Pheromones are chemical signals that are released by an individual and can affect the behavior or physiology of other individuals of the same species.
The other options are not components of the integumentary system that secrete pheromones. The fossa ovalis is a depression in the interatrial septum of the heart, the seminiferous tubule is a structure in the testes where sperm are produced, and the dermal papilla is a structure at the base of a hair follicle that provides nutrients to the hair.
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Q #2: Which of the following ions binds to the troponin complex, initiating the contraction of a muscle?
A. Sodium
B. Potassium
C. Calcium
D. Phosphorus
Answer Explanation
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.
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Q #3: Which of the following layers of skin lack blood vessels?
A. Papillary
B. Epidermis
C. Reticular
D. Hypodermis
Answer Explanation
The layer of skin that lacks blood vessels is the epidermis. The epidermis is the thin outer layer of the skin and does not have any blood vessels within it. It is composed of keratinized, stratified squamous epithelium and is made of four or five layers of epithelial cells, depending on its location in the body.
The other options are not correct because they do contain blood vessels. The papillary layer is part of the dermis, which contains blood vessels. The reticular layer is also part of the dermis and contains blood vessels . The hypodermis is a layer below the dermis and also contains blood vessels.
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Q #4: 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 #5: A study found two processes, Process A and Process B, to be correlated. Which of the following is true for these processes?
A. The study indicates that Process A causes Process B.
B. The study cannot indicate whether Process A and B have a positive relationship.
C. The study does not indicate a causal relationship between the processes.
D. The study cannot indicate whether Process A and B have a negative relationship.
Answer Explanation
The correct answer is c.
The study does not indicate a causal relationship between the processes. A correlation between two processes means that there is a statistical relationship between them, but it does not necessarily imply causation. In other words, just because two processes are correlated does not mean that one causes the other.
b.The study does not indicate that Process A causes Process B.
b.The study can indicate whether Process A and B have a positive relationship if the correlation is positive.
d. The study can indicate whether Process A and B have a negative relationship if the correlation is negative.
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Q #6: 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.
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Q #7: 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 #8: 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
Answer Explanation
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.
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Q #9: Which of the following classes of biological molecules includes enzymes?
A. Lipids
B. Vitamins
C. Carbohydrates
D. Proteins
Answer Explanation
Enzymes are a type of protein that catalyze chemical reactions in the body. Proteins are one of the four main classes of biological molecules, along with lipids, carbohydrates, and nucleic acids.
The other options are not classes of biological molecules that include enzymes. Lipids are a class of molecules that includes fats and oils, vitamins are organic compounds that are essential for normal growth and nutrition, and carbohydrates are a class of molecules that includes sugars and starches.
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Q #10: 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.
