HESI RN
Biology Practice Test
1. In the hierarchical organizational system, which of these is the most restrictive category?
- A. Genus
- B. Class
- C. Kingdom
- D. Species
Correct answer: D
Rationale: In the biological classification hierarchy, species is the most specific level, defining individual organisms that can interbreed. While genus, class, and kingdom are also categories in the hierarchy, they are broader and encompass a wider range of organisms compared to species. Genus groups together similar species, class groups similar orders, and kingdom is the broadest category grouping together similar phyla.
2. Which of the following molecules contains the code required for replication?
- A. Deoxyribonucleic acid (DNA)
- B. Transfer RNA (tRNA)
- C. Messenger RNA (mRNA)
- D. Ribonucleic acid (RNA)
Correct answer: A
Rationale: The correct answer is A: Deoxyribonucleic acid (DNA). DNA contains the genetic information essential for replication, ensuring the accurate transmission of genetic material from one generation to the next. Choice B, Transfer RNA (tRNA), is involved in protein synthesis, not replication. Choice C, Messenger RNA (mRNA), carries genetic information from DNA to the ribosome but does not contain the code for replication. Choice D, Ribonucleic acid (RNA), is a broader category that includes both mRNA and tRNA, but the specific molecule containing the code required for replication is DNA.
3. What are the nitrogenous bases of DNA?
- A. Adenine, cytosine, guanine, and thymine
- B. Adenine, guanine, and uracil
- C. Adenine, guanine, and thymine
- D. Adenine, cytosine, guanine, and uracil
Correct answer: A
Rationale: The correct answer is A: Adenine, cytosine, guanine, and thymine. These are the four nitrogenous bases found in DNA. Adenine pairs with thymine, and cytosine pairs with guanine, forming the complementary base pairs in the double helix structure of DNA. Choice B is incorrect because uracil is a nitrogenous base found in RNA, not DNA. Choice C is incorrect as it is missing cytosine, one of the four bases in DNA. Choice D is incorrect because uracil is not a nitrogenous base in DNA, and it also lacks thymine, which is essential for DNA structure.
4. Which of the following is not true of mitosis?
- A. Mitosis produces daughter cells
- B. Mitosis has five main stages
- C. Mitosis can only be done by haploids
- D. Following mitosis, daughter cells are identical to parent cells
Correct answer: C
Rationale: The correct answer is C. Mitosis occurs in diploid cells and involves stages that result in the production of two identical daughter cells. Haploids do not undergo mitosis, as mitosis is a process specific to diploid cells. Choice A is true as mitosis does produce daughter cells. Choice B is incorrect as mitosis typically consists of four main stages: prophase, metaphase, anaphase, and telophase. Choice D is true, as one of the main outcomes of mitosis is the production of daughter cells that are genetically identical to the parent cell.
5. The bilayer of the cellular membrane consists of phospholipids with all except which of the following scattered throughout?
- A. Nucleic acids
- B. Cholesterol
- C. Proteins
- D. Glycoproteins
Correct answer: A
Rationale: The cellular membrane is composed of a phospholipid bilayer with cholesterol, proteins, and glycoproteins distributed throughout. Nucleic acids are not found within the cellular membrane. Cholesterol helps maintain membrane fluidity, while proteins and glycoproteins play important roles in cell signaling, transport, and structural support.
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