In a well-designed experiment, all variables apart from the treatment should be kept constant between what?.
A. Control group and treatment group.
B. Independent variable and dependent variable.
C. Experimental group and non-experimental group.
D. High level and low level of the independent variable.
In a well-designed experiment, all variables apart from the treatment should be kept constant between the control group and treatment group.
This means researchers can correctly measure the entire effect of the treatment without interference from confounding variables.
Choice B) Independent variable and dependent variable is incorrect because these are not groups but rather variables.
The independent variable is manipulated by the experimenters while the dependent variable is measured to see if it changes as a result of the manipulation.
Choice C) Experimental group and non-experimental group is incorrect because a non-experimental group is not a term used in experimental design.
The correct term for the group that does not receive the treatment is control group.
Choice D) High level and low level of the independent variable is incorrect because these are levels of the independent variable, not groups.
In an experiment, there can be multiple levels of the independent variable, but they are applied to different groups (e.g.
control group, treatment group).
Therefore, the Correct Answer is A.
More Questions on TEAS 7 Science
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Q #1: What is the purpose of using PCR (polymerase chain reaction) in the laboratory?
A. To separate DNA fragments by size.
B. To amplify specific regions of DNA.
C. To sequence DNA fragments.
D. To analyze protein expression levels.
Answer Explanation
The correct answer is choice B.
To amplify specific regions of DNA.
PCR (polymerase chain reaction) is a laboratory technique used to make many copies of a specific region of DNA.
The goal of PCR is to make enough of the target DNA region that it can be analyzed or used in some other way.
PCR has many research and practical applications, including DNA cloning, medical diagnostics, and forensic analysis of DNA.
Choice A is incorrect because PCR does not separate DNA fragments by size. Choice C is incorrect because PCR does not sequence DNA fragments.
Choice D is incorrect because PCR does not analyze protein expression levels.
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Q #2: Which of the following is a consequence of increased viscosity of a fluid?
A. Particles have a decrease in mobility.
B. The fluid will have a lower density.
C. The fluid will have a higher flow rate.
D. The fluid will have a higher pressure.
Answer Explanation
The correct answer is choice A.
An increase in viscosity of a fluid results in a decrease in mobility of particles.
Viscosity is the resistance of a fluid to a change in shape or movement of neighboring portions relative to one another.
It denotes opposition to flow and may be thought of as internal friction between the molecules.
Choice B is incorrect because an increase in viscosity does not affect the density of a fluid.
Choice C is incorrect because an increase in viscosity results in a decrease, not an increase, in flow rate.
Choice D is incorrect because an increase in viscosity does not affect the pressure of a fluid.
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Q #3: A nurse is conducting a research study to compare the effects of two different pain medications on postoperative patients. The nurse randomly assigns the patients to either receive medication A or medication B. Which of the following is the best way to ensure that the study is valid and reliable?
A. Use a large sample size and a standardized procedure for administering the medications.
B. Use a placebo group and a double-blind technique for giving the medications.
C. Use a matched-pairs design and a crossover technique for switching the medications.
D. Use a convenience sample and a pretest-posttest design for measuring the pain levels.
Answer Explanation
The correct answer is choice B.
Using a placebo group and a double-blind technique for giving the medications is the best way to ensure that the study is valid and reliable.
A placebo group helps control for the placebo effect, which can influence the results of a study.
A double-blind technique means that neither the patients nor the researchers know which medication is being given, reducing bias.
Choice A is not the best answer because while a large sample size and standardized procedure can increase reliability, they do not address validity.
Choice C is not the best answer because a matched-pairs design and crossover technique are useful for reducing variability but do not address validity.
Choice D is not the best answer because a convenience sample may not be representative and a pretest-posttest design does not control for extraneous variables.
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Q #4: Which organ in the human body is responsible for the removal of damaged red blood cells and the production of certain types of white blood cells?
A. Spleen
B. Kidneys
C. Pancreas
D. Thyroid gland
Answer Explanation
The correct answer is choice A.
The spleen is an organ in the human body that is responsible for the removal of damaged red blood cells and the production of certain types of white blood cells.
Choice B is incorrect because the kidneys are responsible for filtering waste from the blood and regulating electrolyte balance.
Choice C is incorrect because the pancreas produces hormones and enzymes that aid in digestion.
Choice D is incorrect because the thyroid gland produces hormones that regulate metabolism.
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Q #5: What is the largest vein in the human body that returns deoxygenated blood from the upper half of the body to the right atrium of the heart?
A. Superior vena cava.
B. Inferior vena cava.
C. Pulmonary vein.
D. Renal vein.
Answer Explanation
The correct answer is choice A.
The superior vena cava is the largest vein in the human body that returns deoxygenated blood from the upper half of the body to the right atrium of the heart.
Choice B is incorrect because the inferior vena cava returns deoxygenated blood from the lower half of the body to the right atrium of the heart.
Choice C is incorrect because the pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart.
Choice D is incorrect because the renal vein carries deoxygenated blood from the kidneys to the inferior vena cava.
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Q #6: What is a control group used for in scientific studies?
A. To establish causality by isolating the effect of an independent variable.
B. To establish the effect of a dependent variable on an independent variable.
C. To control the impact of extraneous variables on the dependent variable.
D. To control the impact of extraneous variables on the independent variable.
Answer Explanation
A control group is used in scientific studies to establish causality by isolating the effect of an independent variable.
The control group serves as a baseline or comparison group that does not receive the treatment or intervention being tested.
By comparing the results of the control group to the experimental group, researchers can determine if any observed changes are due to the independent variable or if they are due to chance or other factors.
Choice B is incorrect because a control group is not used to establish the effect of a dependent variable on an independent variable.
Choice C is incorrect because while a control group can help control for the impact of extraneous variables on the dependent variable, its primary purpose is to isolate the effect of the independent variable.
Choice D is incorrect because a control group is not used to control for the impact of extraneous variables on the independent variable.
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Q #7: What is the organelle that encapsulates the contents of the cell and plays a vital role in regulating the movement of substances in and out of the cell?.
A. Ribosome
B. Nucleus
C. Mitochondria
D. Plasma membrane.
Answer Explanation
The plasma membrane is the organelle that encapsulates the contents of the cell and plays a vital role in regulating the movement of substances in and out of the cell.
It is a selectively permeable barrier that separates the internal environment of the cell from the external environment.
Choice A is incorrect because ribosomes are organelles involved in protein synthesis, not in regulating the movement of substances in and out of the cell.
Choice B is incorrect because the nucleus is an organelle that contains the cell’s genetic material, not in regulating the movement of substances in and out of the cell.
Choice C is incorrect because mitochondria are organelles involved in energy production, not in regulating the movement of substances in and out of the cell.
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Q #8: What is hydrogen bonding?
A. The attraction between the relatively positive areas of one molecule and the relatively negative areas of another molecule.
B. The repulsion between the positive and negative charges of two molecules.
C. The attraction between two nonpolar molecules.
D. The attraction between two ionic molecules.
Answer Explanation
Hydrogen bonding is an interaction involving a hydrogen atom located between a pair of other atoms having a high affinity for electrons.
One atom of the pair (the donor), generally a fluorine, nitrogen, or oxygen atom, is covalently bonded to a hydrogen atom, whose electrons it shares unequally; its high electron affinity causes the hydrogen to take on a slight positive charge.
The other atom of the pair (the acceptor), also typically F, N, or O, has an unshared electron pair, which gives it a slight negative charge.
Mainly through electrostatic attraction, the donor atom effectively shares its hydrogen with the acceptor atom, forming a bond.
Choice B) The repulsion between the positive and negative charges of two molecules is incorrect because hydrogen bonding involves attraction, not repulsion.
Choice C) The attraction between two nonpolar molecules is incorrect because hydrogen bonding involves polar molecules.
Choice D) The attraction between two ionic molecules is incorrect because hydrogen bonding involves polar molecules and not ionic molecules.
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Q #9: Why is water sometimes called the "universal solvent"?.
A. Because water dissolves all solutes equally well.
B. Because water is a nonpolar solvent.
C. Because water is good at dissolving ions and polar molecules.
D. Because water is poor at dissolving nonpolar molecules.
Answer Explanation
Water is sometimes called the “universal solvent” because it dissolves more substances than any other liquid.
This is due to its polarity and ability to form hydrogen bonds, which allows it to dissolve ions and polar molecules.
Choice A) Because water dissolves all solutes equally well is incorrect because water does not dissolve all solutes equally well.
Choice B) Because water is a nonpolar solvent is incorrect because water is a polar solvent.
Choice D) Because water is poor at dissolving nonpolar molecules is incorrect because it does not explain why water is called the “universal solvent”.
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Q #10: Which of the following hormones is responsible for regulating the body's metabolism and energy levels?
A. Estrogen
B. Progestin
C. Thyroxine
D. Androgen
Answer Explanation
The correct answer is choice C. Thyroxine.
Thyroxine (T4) is a hormone produced by the thyroid gland that controls your body’s metabolism, the process in which your body transforms the food you eat into energy.
Choice A, Estrogen, is not the correct answer because it is a hormone responsible for the development of female secondary sexual characteristics.
Choice B, Progestin, is not the correct answer because it is a synthetic form of progesterone used in hormonal birth control and hormone replacement therapy.
Choice D, Androgen, is not the correct answer because it is a hormone responsible for the development of male secondary sexual characteristics.
