which of the following describes the primary function of the pyloric sphincter

ATI TEAS 7

TEAS 7 Science Practice Test

1. What is the primary function of the pyloric sphincter?

A. to regulate the movement of food material from the stomach to the duodenum
B. to neutralize stomach acid
C. to prevent digested food materials and stomach acid from entering the esophagus
D. to begin the process of chemical digestion

Correct answer: A

Rationale: The primary function of the pyloric sphincter is to regulate the flow of partially digested food material (chyme) from the stomach into the small intestine, specifically the duodenum. This control is essential for proper digestion and absorption of nutrients in the small intestine. Choices B, C, and D are incorrect. Choice B is incorrect because neutralizing stomach acid is primarily the function of the stomach lining and antacid mechanisms. Choice C is incorrect because preventing the backflow of digested food materials and stomach acid into the esophagus is mainly the role of the lower esophageal sphincter. Choice D is incorrect because the chemical digestion process primarily starts in the stomach through the action of gastric juices, not the pyloric sphincter.

2. What is the energy required to break a chemical bond called?

A. Kinetic energy
B. Potential energy
C. Activation energy
D. Bond energy

Correct answer: C

Rationale: Activation energy is the energy required to break a chemical bond and initiate a chemical reaction. It is the minimum amount of energy needed to start a chemical reaction by breaking bonds in the reactant molecules. Kinetic energy (option A) is the energy of motion and is not directly related to breaking chemical bonds. Potential energy (option B) is stored energy that can be converted into other forms of energy but is not specifically about breaking chemical bonds. Bond energy (option D) refers to the energy required to break a particular chemical bond in a molecule and is not the general term for the energy needed to break any chemical bond. Activation energy is crucial in determining the rate of a chemical reaction as it affects the probability of reactant molecules colliding with sufficient energy to surpass the energy barrier and form products.

3. When a person pushes a box across the floor, which of the following forces is NOT doing work?

A. The person's pushing force
B. The normal force from the floor
C. The gravitational force on the box
D. The frictional force between the box and the floor

Correct answer: B

Rationale: The normal force from the floor is perpendicular to the direction of motion of the box, so it does not contribute to the work being done. Work is only done by forces acting in the direction of motion of an object. In this case, the normal force is acting at a right angle to the motion, hence it does not perform any work on the box. The person's pushing force, the gravitational force, and the frictional force are all acting in the direction of motion of the box, so they contribute to the work being done in moving the box across the floor.

4. Which of the following units is equivalent to a joule?

A. Newton-meter (N·m)
B. Watt (W)
C. Kilogram (kg)
D. Ampere (A)

Correct answer: A

Rationale: A joule is the SI unit of energy and work, defined as the work done by a force of one newton acting over a distance of one meter. Therefore, a joule is equivalent to a newton-meter (N·m), which represents the product of force (newton) and distance (meter). This unit reflects the energy transferred when a force of one newton moves an object one meter. Choice B, Watt (W), is the unit of power and is not equivalent to a joule. Choice C, Kilogram (kg), is a unit of mass. Choice D, Ampere (A), is the unit of electric current.

5. Which term describes the ability of a substance to conduct electricity?

A. Reactivity
B. Density
C. Conductivity
D. Viscosity

Correct answer: C

Rationale: Conductivity is the correct term used to describe the ability of a substance to conduct electricity. Reactivity is the measure of a substance's tendency to undergo chemical reactions. Density refers to the mass per unit volume of a substance, while viscosity is a measure of a fluid's resistance to flow. In the context of conducting electricity, conductivity is the most appropriate term as it directly relates to the substance's electrical conductive properties.