HESI RN
Biology Practice Test
1. Which of the following organelles is the site of cellular respiration?
- A. Nucleus
- B. Mitochondria
- C. Lysosomes
- D. Ribosomes
Correct answer: B
Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouse of the cell because they generate most of the cell's supply of ATP through cellular respiration. The other organelles listed, such as the nucleus (choice A), lysosomes (choice C), and ribosomes (choice D), do not play a direct role in cellular respiration. The nucleus contains genetic material, lysosomes are involved in digestion and waste removal, and ribosomes are responsible for protein synthesis.
2. During which stage of mitosis do the chromosomes gather on either side of the separating cell?
- A. Metaphase
- B. Telophase
- C. Anaphase
- D. Prophase
Correct answer: B
Rationale: The correct answer is B, Telophase. During telophase, the chromosomes gather at opposite poles of the cell as the nuclear envelopes start to form around them, indicating the end of cell division. Choices A, C, and D are incorrect because during metaphase, the chromosomes align in the middle of the cell; in anaphase, the chromosomes separate and move towards opposite poles; and in prophase, the chromosomes condense and the nuclear envelope breaks down, respectively.
3. Which of the following is the term used to represent alternative versions of a gene?
- A. Alleles
- B. Binary fission
- C. Heterozygous
- D. Homozygous
Correct answer: A
Rationale: The correct answer is A: Alleles. Alleles are different versions of a gene that can exist at a specific locus on a chromosome. This term specifically refers to the different forms of a gene that can exist. Choices B, C, and D are incorrect because they do not represent alternative versions of a gene. Binary fission is a form of asexual reproduction in single-celled organisms, while heterozygous and homozygous refer to the genetic makeup of an individual rather than alternative versions of a gene.
4. Which of the following serves as the information processing and administrative center of the cell?
- A. Golgi apparatus
- B. Cytoplasm
- C. Nucleus
- D. Lysosomes
Correct answer: C
Rationale: The correct answer is C, the nucleus. The nucleus is indeed the information processing and administrative center of the cell as it contains the genetic material (DNA) and is responsible for controlling cellular activities. The Golgi apparatus (Choice A) is involved in processing and packaging proteins, the cytoplasm (Choice B) is the fluid that fills the cell and provides a medium for organelles to be suspended, and lysosomes (Choice D) are responsible for digesting waste materials and foreign invaders. Therefore, the nucleus is the most appropriate choice for the given function.
5. What is the composition of the cellular membrane?
- A. A bilayer of phospholipid molecules
- B. A single layer of phospholipid molecules
- C. Proteins that act as transport highways
- D. Carbohydrates
Correct answer: A
Rationale: The cellular membrane is primarily composed of a phospholipid bilayer, which consists of two layers of phospholipid molecules. These molecules have a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tail, creating a barrier that separates the internal cellular environment from the external surroundings. While proteins are embedded within this bilayer and act as transport channels, receptors, and structural support, carbohydrates are found on the outer surface of the membrane for cell recognition and signaling purposes. Therefore, the correct answer is a bilayer of phospholipid molecules.
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