HESI RN
Biology Practice Test
1. Which of the following statements is true if a molecule exhibits adhesion?
- A. Two molecules of the same substance have the ability to stay bonded to one another
- B. The molecule has the ability to bond to or attract other molecules
- C. A molecule has the ability to increase its heat when necessary
- D. The molecule has the ability to form hydrogen bonds
Correct answer: B
Rationale: The correct statement is that if a molecule exhibits adhesion, it has the ability to bond to or attract other molecules. Adhesion refers to the ability of a molecule to bind to or attract different types of molecules. Choice A is incorrect because adhesion is about bonding to different molecules, not the same substance. Choice C is incorrect as adhesion does not relate to the ability of a molecule to increase its heat. Choice D is incorrect because forming hydrogen bonds is a specific type of interaction and not a general characteristic of molecules exhibiting adhesion.
2. Which of the following is not found in a prokaryotic cell?
- A. Plasma membrane
- B. Cytoplasm
- C. Nucleus
- D. Ribosomes
Correct answer: C
Rationale: The correct answer is C, 'Nucleus.' Prokaryotic cells do not have a defined nucleus, unlike eukaryotic cells. The plasma membrane, cytoplasm, and ribosomes are all components found in prokaryotic cells. The plasma membrane surrounds the cell and regulates what enters and exits, the cytoplasm is the gel-like substance that fills the cell, and ribosomes are responsible for protein synthesis.
3. Which of the following is a lipid that is a membrane component and a precursor to significant hormones?
- A. Nucleic acids
- B. Proteins
- C. Carbohydrates
- D. Steroids
Correct answer: D
Rationale: The correct answer is D, Steroids. Steroids are a type of lipid that function as essential components of cell membranes and serve as precursors for significant hormones like estrogen and testosterone. Nucleic acids (choice A) are not lipids but are molecules like DNA and RNA that store genetic information. Proteins (choice B) and carbohydrates (choice C) are biomolecules but are not lipids and do not serve as precursors for hormones or membrane components.
4. The term pleiotropy is best defined as which of the following?
- A. A situation in which one gene remains unexpressed
- B. One gene influencing multiple, seemingly unrelated phenotypic traits
- C. Two genes affected by a single allele
- D. A condition in which multiple genes are missing
Correct answer: B
Rationale: Pleiotropy is best defined as one gene influencing multiple, seemingly unrelated phenotypic traits. This phenomenon showcases the multifunctionality of genes, where a single gene can have effects on various aspects of an organism's phenotype. Choices A, C, and D do not accurately capture the concept of pleiotropy. Option A refers to gene expression, not pleiotropy. Option C describes genetic interactions but not in the context of pleiotropy. Option D talks about missing genes, which is unrelated to the definition of pleiotropy.
5. What is the most significant contributor to cellular function?
- A. Proteins
- B. Phospholipids
- C. Carbohydrates
- D. Fatty acids
Correct answer: A
Rationale: The correct answer is A: Proteins. Proteins are the most significant contributor to cellular function as they play crucial roles in almost all biological processes. They act as enzymes that catalyze reactions, are involved in cell signaling pathways, and provide structural support to cells. Phospholipids (Choice B), while important for cell membrane structure, do not have the same diverse functions as proteins in cellular processes. Carbohydrates (Choice C) primarily serve as an energy source and structural components but are not as versatile in cellular functions as proteins. Fatty acids (Choice D) are essential components of cell membranes and energy storage molecules but do not have the same broad range of functions as proteins in cellular processes.
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