HESI A2
HESI A2 Biology Practice Test
1. The sum of all chemical reactions that occur in an organism is:
- A. product
- B. respiration
- C. metabolism
- D. synthesis
Correct answer: C
Rationale: Metabolism is the sum of all chemical reactions that occur within an organism to maintain life. It involves all the processes that break down molecules to release energy (catabolism) and build new molecules to support growth and maintenance (anabolism). Respiration refers specifically to the process of generating energy from the breakdown of glucose molecules. Synthesis is the creation of complex molecules from simpler ones. Therefore, metabolism is the most comprehensive term that encompasses all these processes within an organism.
2. Cells that line the inner or outer surfaces of organs or body cavities are often linked together by intimate physical connections. These connections are referred to as ______.
- A. Separate desmosomes
- B. Ronofilaments
- C. Tight junctions
- D. Fascia adherens
Correct answer: C
Rationale: The correct answer is C: Tight junctions. Tight junctions, also known as zonula occludens, are the intimate physical connections between cells that line the inner or outer surfaces of organs or body cavities. These junctions form a virtually impermeable barrier to fluid, creating a tight seal between the cells. This helps in maintaining the integrity and function of the tissue as well as regulating the movement of substances across the cell layer. Choice A, Separate desmosomes, are cell structures that provide strong adhesion between cells but do not create a barrier to fluid. Choice B, Ronofilaments, is not a term used to describe the connections between cells. Choice D, Fascia adherens, are another type of cell junction involved in cell adhesion, but they are different from tight junctions in terms of their structure and function.
3. The force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere is the ______.
- A. Atmospheric pressure
- B. Barometric density
- C. Aneroid pressure
- D. Barometric pressure
Correct answer: A
Rationale: Atmospheric pressure is the correct term for the force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere. It is commonly measured in units such as pascals, millibars, or inches of mercury. Barometric density and aneroid pressure are not accurate descriptions for this phenomenon. Barometric density refers to the density of the atmosphere at a particular location, while aneroid pressure is linked to a type of barometer but not a comprehensive term for the force exerted by the weight of air.
4. What is the main function of the cell membrane?
- A. Energy production
- B. Communication
- C. Protein synthesis
- D. Waste removal
Correct answer: B
Rationale: The main function of the cell membrane is communication. It acts as a barrier that regulates the passage of substances in and out of the cell, maintaining cellular homeostasis. Choices A, C, and D are incorrect because energy production occurs in the mitochondria, protein synthesis takes place in the ribosomes, and waste removal is primarily handled by the lysosomes and other organelles within the cell.
5. Which gives the order of four taxonomic categories from least to most specific?
- A. Kingdom, phylum, class, order
- B. Kingdom, phylum, order, class
- C. Kingdom, order, phylum, class
- D. Kingdom, class, order, phylum
Correct answer: A
Rationale: The correct order of the four taxonomic categories from least to most specific is Kingdom, phylum, class, and order. This sequence adheres to the hierarchical system of classification where organisms are grouped based on shared characteristics, becoming more specific as you move from Kingdom to order. Choice B is incorrect as the order of 'order' and 'class' is swapped. Choice C is incorrect as 'order' precedes 'phylum' instead of following it. Choice D is incorrect as 'class' should come before 'order'.
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