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.

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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.

 
  Control Group Definition and Examples

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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.

 

Therefore, the Correct Answer is A.

More Questions on TEAS 7 Science Test 4

Question 1:

Which hormone is responsible for the development of female secondary sexual characteristics such as breast development, menstrual cycle, and widening of hips?

A. Progesterone

B. Testosterone

C. Estrogen

D. FSH

The Correct Answer is C.

The correct answer is choice C. Estrogen.

Estrogen is a steroid hormone responsible for the development of female secondary sexual characteristics such as breast development, menstrual cycle, and widening of hips.

Choice A, Progesterone, is not the correct answer because it is required to maintain pregnancy and delivery.

Choice B, Testosterone, is not the correct answer because it is a hormone produced by the testes which controls the development of male secondary sexual characteristics.

Choice D, FSH (Follicle Stimulating Hormone), is not the correct answer because it stimulates the growth of ovarian follicles in females and regulates spermatogenesis in males.


Question 2:

How do neurons communicate with each other?

A. Through electrical signals only

B. Through chemical signals only

C. Through electrical and chemical signals

D. Through mechanical signals only.

The Correct Answer is C.

Neurons communicate with each other through both electrical and chemical signals.

The electrical signal, or action potential, runs from the cell body area to the axon terminals, through a thin fiber called axon.

Neurons: How the Brain Communicates | Mental Health America

Neurons also communicate with one another at junctions called synapses.

At a synapse, one neuron sends a message to a target neuron—another cell.

Most synapses are chemical; these synapses communicate using chemical messengers.

Choice A is incorrect because neurons communicate not only through electrical signals but also through chemical signals.

Choice B is incorrect because neurons communicate not only through chemical signals but also through electrical signals.

Choice D is incorrect because neurons do not communicate through mechanical signals.


Question 3:

What is the normal flora?

A. A variety of microbial species found in certain areas of the human body.

B. A group of infectious parasites that cause diarrheal diseases.

C. The genetic material of bacteria housed within a true nucleus.

D. The protein coat surrounding the viral genome.

The Correct Answer is A.

The normal flora refers to the microbial community that colonizes on the skin and mucus membrane .

Normal flora can be found in many sites of the human body including the skin, respiratory tract, urinary tract, and the digestive tract.

Frontiers | Microbial Colonization From the Fetus to Early Childhood„A  Comprehensive Review

Choice B is incorrect because normal flora does not refer to a group of infectious parasites that cause diarrheal diseases .

Choice C is incorrect because normal flora does not refer to the genetic material of bacteria housed within a true nucleus .

Choice D is incorrect because normal flora does not refer to the protein coat surrounding the viral genome .


Question 4:

A patient with chronic kidney disease is at risk for developing which of the following electrolyte imbalances?

A. Decrease in the concentration of calcium in the glomerulus.

B. Increase in the concentration of potassium in the blood.

C. Decrease in the concentration of sodium in the blood.

D. Increase in the concentration of magnesium in the blood.

The Correct Answer is B.

The correct answer is choice B.

A patient with chronic kidney disease is at risk for developing an increase in the concentration of potassium in the blood.

The kidneys play a pivotal role in the regulation of electrolyte balance.

With progressive loss of kidney function, derangements in electrolytes inevitably occur and contribute to poor patient outcomes123.

Choice A is incorrect because calcium concentration is not regulated in the glomerulus.

Choice C is incorrect because chronic kidney disease can result in either an increase or decrease in sodium concentration in the blood.

Choice D is incorrect because chronic kidney disease does not necessarily result in an increase in magnesium concentration in the blood.


Question 5:

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.

The Correct Answer is A.

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.


Question 6:

How does the use of a catalyst affect the activation energy of a chemical reaction?

A. It increases the activation energy required for the reaction.

B. It decreases the activation energy required for the reaction.

C. It has no effect on the activation energy required for the reaction.

D. It increases the rate of reaction but has no effect on the activation energy.

The Correct Answer is B.

The correct answer is choice B.

It decreases the activation energy required for the reaction.

A catalyst provides a new reaction pathway in which a lower activation energy is offered.

This allows more reactant molecules to collide with enough energy to surmount the smaller energy barrier, increasing the rate of reaction 2.

Choice A, It increases the activation energy required for the reaction, is not the correct answer because it describes the opposite effect of a catalyst.

Choice C, It has no effect on the activation energy required for the reaction, is not the correct answer because a catalyst does have an effect on activation energy.

Choice D, It increases the rate of reaction but has no effect on the activation energy, is not the correct answer because a catalyst increases the rate of reaction by decreasing the activation energy.


Question 7:

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.

The Correct Answer is B.

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.

 
  Polymerase chain reaction - Wikipedia

 

 

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.


Question 8:

What is a primer in DNA sequencing?

A. A short piece of double-stranded DNA that binds to the template DNA and acts as a "starter" for the polymerase.

B. A short piece of double-stranded DNA that binds to the primer and acts as a "starter" for the template.

C. A short piece of single-stranded DNA that binds to the template DNA and acts as a "starter" for the polymerase.

D. A short piece of single-stranded DNA that binds to the polymerase and acts as a "starter" for the template.

The Correct Answer is C.

A primer is a short single-stranded DNA fragment used in certain laboratory techniques, such as the polymerase chain reaction (PCR).

In the PCR method, a pair of primers hybridizes with the sample DNA and defines the region that will be amplified.

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Choice A) A short piece of double-stranded DNA that binds to the template DNA and acts as a “starter” for the polymerase is incorrect because primers are single-stranded, not double-stranded.

Choice B) A short piece of double-stranded DNA that binds to the primer and acts as a “starter” for the template is incorrect because it does not make sense for a primer to bind to itself.

Choice D) A short piece of single-stranded DNA that binds to the polymerase and acts as a “starter” for the template is incorrect because primers bind to the template DNA, not to the polymerase.

Note: DNA primers are used instead of RNA primers in DNA sequencing and PCR because DNA is more stable, specific, and compatible with the enzymes and processes involved in these techniques.


Question 9:

In which type of tissue would you find a fibrous protein that provides strength and protection to the body, particularly in the skin, hair, and nails?

A. Keratin

B. Collagen

C. Elastin

D. Actin

The Correct Answer is A.

The correct answer is choice A. Keratin.

Keratin is a fibrous protein that provides strength and protection to the body, particularly in the skin, hair, and nails.

 
  Keratin Overview, Structure & Function | What is Keratin? - Video & Lesson  Transcript | Study.com

 

 

 

It is found in epithelial tissue, which covers the body’s surface and lines its internal organs and cavities.

Choice B.

 

Collagen is incorrect because collagen is a fibrous protein that provides strength and support to connective tissues such as tendons, ligaments, and cartilage.

Choice C.

Elastin is incorrect because elastin is a protein that provides elasticity to tissues such as skin and blood vessels.

Choice D.

Actin is incorrect because actin is a protein that plays a role in muscle contraction and cell movement.


Question 10:

A nurse is reviewing the results of a patient’s DNA sequencing test, which was performed to diagnose a genetic disorder.

The nurse notices that the patient has a mutation in one of the bases of the DNA. Which of the following is the correct term for this type of mutation?

A. Deletion

B. Insertion

C. Substitution

D. Inversion

The Correct Answer is C.

The correct answer is choice C. Substitution.

A substitution mutation is a type of point mutation where one base in the DNA sequence is replaced by another base.

 

 
  Types of mutations - Understanding Evolution

 

 

Choice A is incorrect because a deletion mutation occurs when one or more bases are removed from the DNA sequence.

Choice B is incorrect because an insertion mutation occurs when one or more bases are added to the DNA sequence.

Choice D is incorrect because an inversion mutation occurs when a segment of DNA is reversed within the chromosome.