HESI A2
HESI A2 Biology Practice Test 2024
1. What is the fundamental unit of life?
- A. Atom
- B. Cell
- C. Tissue
- D. Organ
Correct answer: B
Rationale: The correct answer is 'B: Cell.' Cells are indeed the fundamental unit of life as they are responsible for all living functions, including growth, reproduction, and maintaining homeostasis. While atoms are the basic building blocks of matter, cells are the smallest structural and functional unit of living organisms. Choices C and D, tissue and organ respectively, are composed of multiple cells working together and are not considered the basic unit of life.
2. Which animal has an open transport system?
- A. Grasshopper
- B. Earthworm
- C. Dolphin
- D. Chicken
Correct answer: B
Rationale: The correct answer is B: Earthworm. Earthworms have an open circulatory system, meaning their blood and interstitial fluid are not enclosed in blood vessels. Instead, the blood flows freely within the body cavity, allowing for direct exchange of nutrients and waste products with surrounding tissues. This lack of a closed transport system is a characteristic feature of earthworms. Choices A, C, and D are incorrect because grasshoppers, dolphins, and chickens have closed circulatory systems where the blood is enclosed within blood vessels, unlike earthworms.
3. Which one of the following best describes the function of a cell membrane?
- A. It controls the substances entering and leaving the cell.
- B. It maintains the cell's shape.
- C. It controls the substances entering the cell.
- D. It supports the cell's structures.
Correct answer: A
Rationale: The correct answer is A. The function of a cell membrane is to control the substances entering and leaving the cell. The cell membrane is selectively permeable, allowing it to regulate the movement of ions and molecules in and out of the cell to maintain internal balance and proper function. Choice B is incorrect because while the cell membrane does provide some structural support, its primary function is not to maintain the cell's shape. Choice C is incorrect because the cell membrane controls both the substances entering and leaving the cell, not just those entering. Choice D is incorrect as the primary function of the cell membrane is not to support the cell's structures but to regulate the movement of substances.
4. Which of the following types of hormones can diffuse through the cell membrane to bind to receptors inside the cell and stimulate a chemical response to a target cell?
- A. fat-soluble hormones
- B. amino acid derivatives
- C. hydrophilic hormones
- D. water-soluble hormones
Correct answer: A
Rationale: The correct answer is A: fat-soluble hormones. Fat-soluble hormones are able to diffuse through the cell membrane to bind to receptors inside the cell. This is because they are lipophilic, allowing them to cross the lipid bilayer easily. Once inside the cell, fat-soluble hormones can directly affect gene expression or cell function. Choice B, amino acid derivatives, and choice C, hydrophilic hormones, are not able to diffuse through the cell membrane as they are not lipophilic. Therefore, they cannot bind to receptors inside the cell. Choice D, water-soluble hormones, also cannot diffuse through the cell membrane as it is hydrophilic, making it unable to reach receptors inside the cell.
5. What is the primary function of the endoplasmic reticulum in a cell?
- A. Energy production
- B. Protein synthesis
- C. Waste removal
- D. Transport of materials
Correct answer: D
Rationale: The endoplasmic reticulum's primary function is the transport of materials within the cell. It acts as a network of membranes to assist in the transportation of proteins and other substances throughout the cell. Choice A, 'Energy production,' is incorrect because the endoplasmic reticulum is not directly involved in energy production. Choice B, 'Protein synthesis,' is incorrect as protein synthesis mainly occurs in ribosomes, although the endoplasmic reticulum is involved in modifying and transporting proteins. Choice C, 'Waste removal,' is also incorrect as waste removal is primarily handled by other organelles like lysosomes and peroxisomes.
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