which muscle is responsible for breathing

HESI A2

Anatomy HESI A2 Practice Test

1. Which muscle is responsible for breathing?

A. Diaphragm
B. Intercostal muscles
C. Rectus abdominis
D. Pectoralis major

Correct answer: A

Rationale: The diaphragm is the primary muscle responsible for breathing. It is a large, dome-shaped muscle located at the base of the chest cavity. When it contracts, it flattens, increasing the volume of the chest cavity and causing inhalation. When it relaxes, it returns to its dome shape, decreasing the volume of the chest cavity and causing exhalation. The intercostal muscles, located between the ribs, assist the diaphragm in breathing by expanding and contracting the chest cavity. The rectus abdominis and pectoralis major are not directly involved in the process of breathing.

2. If someone is disseminating information, what are they doing?

A. Hiding it
B. Broadcasting it
C. Destroying it
D. Withholding it

Correct answer: B

Rationale: The correct answer is B: 'Broadcasting it.' Disseminating information means spreading or sharing it widely to reach a broader audience. Choice A, 'Hiding it,' is incorrect as disseminating involves making information known, not concealing it. Choice C, 'Destroying it,' is incorrect as disseminating means to distribute, not to eliminate. Choice D, 'Withholding it,' is incorrect because withholding information means keeping it back rather than sharing it openly.

3. ___________ is a symbiotic relationship in which one organism benefits and the other is not affected.

A. Mutualism
B. Parasitism
C. Commensalism
D. Competition

Correct answer: C

Rationale: The correct answer is 'Commensalism.' In commensalism, one organism benefits from the relationship while the other is neither helped nor harmed. This type of symbiotic relationship is characterized by one organism deriving a benefit, such as food or shelter, without impacting the other organism in any significant way. Choice A, 'Mutualism,' is a symbiotic relationship in which both organisms benefit. Choice B, 'Parasitism,' is a symbiotic relationship in which one organism benefits at the expense of the other. Choice D, 'Competition,' refers to a relationship in which organisms compete for limited resources, with both being affected in terms of access to resources.

4. What is another word for contemptuous?

A. Sympathetic
B. Exhausted
C. Scornful
D. Insensitive

Correct answer: C

Rationale: The word 'contemptuous' means showing disdain or scorn for something or someone. Therefore, the word 'scornful' is the most closely related synonym to 'contemptuous' in this list. 'Sympathetic' means showing compassion, 'exhausted' means very tired, and 'insensitive' means lacking empathy. These options do not convey the same meaning as 'contemptuous'.

5. Which element would you expect to be least reactive?

A. Li
B. Cr
C. Nd
D. Xe

Correct answer: D

Rationale: Xenon (Xe) is a noble gas located in Group 18 of the periodic table. Noble gases are known for their stable and unreactive nature due to having a full outer shell of electrons. Therefore, xenon would be expected to be the least reactive among the given elements. Choice A (Li) is a metal in Group 1 of the periodic table, which tends to be reactive, especially with water. Choice B (Cr) is a transition metal known for its reactivity in some forms. Choice C (Nd) is a rare earth element, which can exhibit varying reactivity depending on the compound or environment.