HESI A2 Biology Practice Test

Correct Answer: A

Rationale: The correct answer is A: A segment of DNA. Genes are segments of DNA that contain the instructions for building proteins and controlling various processes in an organism. DNA is the genetic material that carries hereditary information and is passed down from parents to offspring. Option B is incorrect because genes are not bead-like structures on chromosomes but are located within chromosomes. Option C is incorrect because genes are not protein molecules themselves but may code for proteins. Option D is incorrect because genes are not made up of RNA but rather DNA.

Correct Answer: A

Rationale: The correct order of the hierarchy in biological classification is Kingdom, Phylum, Class, Order, Family, Genus, and Species. This system is known as the Linnaean taxonomy. Kingdom is the broadest category, followed by Phylum which groups organisms based on major body features. Class further refines this classification, followed by Order, which organizes similar families. Family groups similar genera, and Genus is a group of closely related species. Finally, Species is the most specific category, representing individual organisms. This hierarchical structure allows for easy organization and categorization of living organisms based on shared characteristics. Choices B, C, and D are incorrect because they do not follow the correct order of the biological classification hierarchy.

Correct Answer: D

Rationale: The correct answer is D because all the statements mentioned in choices A, B, and C are true. A: The respiratory system consists of all organs involved in breathing, including the nose, pharynx, larynx, trachea, bronchi, and lungs. B: Organs included in the respiratory system are the nose, pharynx, larynx, trachea, bronchi, and lungs. C: The respiratory system conveys oxygen into our bodies and removes carbon dioxide from our bodies. Therefore, as all three statements are true, the correct answer is D - All of the Above. The other choices are incorrect because they do not encompass all the organs involved in the respiratory system or the functions it performs.

Correct Answer: A

Rationale: Epithelial cells are correct to be classified as polarized because they have distinct apical and basal surfaces. The apical surface faces the external environment or a body cavity, while the basal surface is anchored to the underlying connective tissue. This polarity is essential for the specialized functions of epithelial cells, such as absorption, secretion, and transportation. Therefore, choice A is the correct answer. Choices B and C are incorrect because epithelial cells are not neutral and are not necessarily larger than other cells. Choice D is incorrect because epithelial cells do have unique characteristics that differentiate them from other cell types.

Correct Answer: A

Rationale: The correct answer is A: Bacteria. Eukaryotic cells have a defined nucleus and membrane-bound organelles, which bacteria lack. Dogs, humans, and onions are all multicellular organisms that possess eukaryotic cells. Bacteria, being prokaryotic, do not have a distinct nucleus or membrane-bound organelles, leading to the conclusion that they do not have eukaryotic cells.