HESI A2
HESI A2 Biology Practice Test
1. Which of the following are components of the endocrine system?
- A. The pituitary gland
- B. The thyroid gland
- C. The adrenal glands
- D. All of the Above
Correct answer: D
Rationale: The endocrine system comprises a network of glands that produce and release hormones to regulate bodily functions. The pituitary gland, thyroid gland, and adrenal glands are essential components of this system. The pituitary gland secretes various hormones that control other glands and some body functions. The thyroid gland regulates metabolism, growth, and energy levels by producing thyroid hormones. The adrenal glands produce hormones involved in stress response, metabolism, and immune function. Therefore, all of the above glands are integral parts of the endocrine system, making choice D the correct answer.
2. What are plasma membranes mostly made of?
- A. Proteins
- B. Carbohydrates
- C. Lipids
- D. Nucleotides
Correct answer: C
Rationale: The correct answer is C: Lipids. Plasma membranes are primarily composed of lipids, specifically phospholipids, which form a lipid bilayer. While proteins are also an essential component of plasma membranes, they are not the primary constituent. Carbohydrates are present on the outer surface of the membrane but are not the main structural component. Nucleotides are the building blocks of nucleic acids like DNA and RNA and are not the main constituents of plasma membranes.
3. Which of the following is not found within a bacterial cell?
- A. mitochondria
- B. DNA
- C. vesicles
- D. ribosome
Correct answer: A
Rationale: The correct answer is A: mitochondria. Mitochondria are not found in bacterial cells. Bacterial cells lack membrane-bound organelles like mitochondria, which are commonly found in eukaryotic cells. Choices B, C, and D are all components that can be found within a bacterial cell. Bacterial cells contain DNA as their genetic material, vesicles for various cellular functions, and ribosomes for protein synthesis. Therefore, the presence of mitochondria is the distinguishing factor that is not found in bacterial cells, making option A the correct answer.
4. In a phospholipid molecule, the head:
- A. Is hydrophilic
- B. Is hydrophobic
- C. Is on the inner side of the layer
- D. Both A and C
Correct answer: D
Rationale: The head of a phospholipid is hydrophilic (water-loving) and is located on the outer side of the lipid bilayer, interacting with water molecules. This arrangement positions the hydrophobic tails inward, away from water. Therefore, the correct answer is D. Choice A is incorrect because the head is hydrophilic, not hydrophobic. Choice B is incorrect as the head is on the outer side, not the inner side of the layer.
5. What is DNA made of?
- A. Proteins
- B. Nucleotides
- C. Lipids
- D. Carbohydrates
Correct answer: B
Rationale: DNA is made up of nucleotides, which are the building blocks of genetic material. Choice A (Proteins) is incorrect because while proteins play a crucial role in the body, they are not the building blocks of DNA. Choice C (Lipids) and Choice D (Carbohydrates) are also incorrect as they are not the primary components of DNA.
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