HESI A2
HESI A2 Biology Practice Test
1. A child is sick. They have a body temperature that exceeds 37ºC. The body senses this and begins to sweat in order to lower the temperature. What is this an example of?
- A. Positive feedback loop
- B. Negative feedback loop
- C. Both
- D. None of the above
Correct answer: B
Rationale: This is an example of a negative feedback loop. In a negative feedback loop, the body's response (sweating) works to counteract the initial stimulus of a high body temperature by cooling the body down. The goal is to return the body to homeostasis, maintaining a stable internal environment. Positive feedback loops amplify the initial stimulus rather than counteracting it, which is not the case here. Therefore, choices A and C are incorrect. Choice D is also incorrect as the situation described fits the characteristics of a negative feedback loop.
2. Which form of fermentation is used to produce beer?
- A. Lactic acid fermentation
- B. Acetic acid fermentation
- C. Propionic acid fermentation
- D. Ethyl alcohol fermentation
Correct answer: D
Rationale: The correct answer is D, Ethyl alcohol fermentation. During beer production, yeast metabolizes sugars in the wort to produce ethanol (ethyl alcohol) and carbon dioxide, which are responsible for the alcohol content and carbonation in beer. Choices A, B, and C are incorrect because lactic acid fermentation produces lactic acid, acetic acid fermentation produces acetic acid, and propionic acid fermentation produces propionic acid, none of which are used in the production of beer.
3. What is the most important component of the cell, contributing to protection, communication, and the passage of substances?
- A. Cytoplasm
- B. Cell Membrane
- C. Cytoskeleton
- D. Vacuole
Correct answer: B
Rationale: The cell membrane is the correct answer. It is the most important component of the cell as it provides protection, facilitates communication, and regulates the passage of substances in and out of the cell. The cytoplasm (Choice A) is the gel-like substance within the cell that holds organelles, but it is not primarily responsible for the functions mentioned in the question. The cytoskeleton (Choice C) provides structural support to the cell but is not directly involved in protection, communication, or substance passage. Vacuoles (Choice D) are responsible for storage and maintaining turgor pressure but do not play a primary role in the functions specified in the question.
4. A cell that does not contain membrane-bound organelles or a defined nucleus would be classified as:
- A. eukaryotic
- B. embryonic
- C. prokaryotic
- D. symbiotic
Correct answer: C
Rationale: A cell that does not contain membrane-bound organelles or a defined nucleus is classified as prokaryotic. Prokaryotic cells lack a true nucleus, and their genetic material is typically found in a region called the nucleoid. Examples of prokaryotic organisms include bacteria and archaea. Eukaryotic cells, on the other hand, contain membrane-bound organelles and a true nucleus, distinguishing them from prokaryotic cells. Embryonic and symbiotic classifications are not directly related to the presence of organelles or a nucleus in cells.
5. What is the fundamental unit of life?
- A. Atom
- B. Cell
- C. Tissue
- D. Organ
Correct answer: B
Rationale: The correct answer is 'B: Cell.' Cells are indeed the fundamental unit of life as they are responsible for all living functions, including growth, reproduction, and maintaining homeostasis. While atoms are the basic building blocks of matter, cells are the smallest structural and functional unit of living organisms. Choices C and D, tissue and organ respectively, are composed of multiple cells working together and are not considered the basic unit of life.
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