HESI RN
Biology Test
1. Water is a polar molecule that can be:
- A. cohesive and corrosive
- B. cohesive and adhesive
- C. electrostatic and ionic
- D. repellent and attractive
Correct answer: B
Rationale: Water is a polar molecule due to an uneven distribution of electrons, allowing it to form hydrogen bonds. This property makes water both cohesive (attracted to itself) and adhesive (attracted to other substances). Choice A is incorrect because water is not corrosive; rather, it is a solvent. Choices C and D are incorrect as they do not describe the cohesive and adhesive properties of water.
2. The liver is an organ responsible for detoxifying the body of many harmful substances. You might expect the liver to contain a high amount of which of the following?
- A. Rough endoplasmic reticulum
- B. Smooth endoplasmic reticulum
- C. Mitochondria
- D. Lysosomes
Correct answer: B
Rationale: The correct answer is B: Smooth endoplasmic reticulum. The liver contains a high amount of smooth endoplasmic reticulum because it plays a significant role in detoxification processes, such as the synthesis of detoxifying enzymes and lipids. Choice A (Rough endoplasmic reticulum) is incorrect because the rough endoplasmic reticulum is more involved in protein synthesis and processing. Choice C (Mitochondria) is incorrect as mitochondria are primarily responsible for energy production. Choice D (Lysosomes) is incorrect because lysosomes are organelles involved in intracellular digestion and waste removal, not specifically related to detoxification.
3. 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.
4. What do prokaryotic cells lack in comparison to eukaryotic cells?
- A. A defined nucleus and a series of membrane-bound organelles
- B. A defined nucleus and no membrane-bound organelles
- C. No defined nucleus and a series of membrane-bound organelles
- D. No defined nucleus and no membrane-bound organelles
Correct answer: D
Rationale: Prokaryotic cells are characterized by the absence of a defined nucleus and membrane-bound organelles. Choice A is incorrect because prokaryotic cells lack membrane-bound organelles. Choice B is incorrect because prokaryotic cells lack both a defined nucleus and membrane-bound organelles. Choice C is incorrect as prokaryotic cells have no defined nucleus. Therefore, the correct answer is D.
5. 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.
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