HESI A2
Biology HESI A2 Practice Test
1. In the scientific process, which of the following is a statement or explanation of certain events or happenings?
- A. hypothesis
- B. observation
- C. experiment
- D. conclusion
Correct answer: A
Rationale: A hypothesis is a statement or explanation of certain events or phenomena based on observations and prior knowledge. It is a testable prediction that guides the scientific investigation process. By formulating a hypothesis, scientists can make predictions and design experiments to gather data and test the validity of the hypothesis. Observations (choice B) involve gathering information through the senses. Experiments (choice C) are procedures carried out to support or refute a hypothesis. Conclusions (choice D) are deductions made based on the results of experiments and observations, but they are not the initial statement or explanation of events or happenings.
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. Which of the following is not true about antibiotics?
- A. They can interfere with the bacteria's ability to survive
- B. They can affect how bacteria multiply
- C. They can cause more bacteria to grow
- D. They only work on bacteria
Correct answer: C
Rationale: The correct answer is C. Antibiotics do not cause more bacteria to grow. They work by interfering with the bacteria's ability to survive, affecting how they multiply, or killing the bacteria cells. Antibiotics specifically target bacteria, so they do not promote the growth of more bacteria. Choices A, B, and D are true statements about antibiotics as they accurately describe how antibiotics work and their specific action on bacteria.
4. What happens to messenger RNA when it reaches the cytoplasm?
- A. It attaches to a ribosome.
- B. It unzips, exposing nitrogen bases.
- C. It pairs with the DNA bases.
- D. It pulls free of the DNA strand.
Correct answer: A
Rationale: Messenger RNA (mRNA) carries genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm. When mRNA reaches the cytoplasm, it attaches to a ribosome. The ribosome functions as the site for protein synthesis through translation, where the genetic code carried by mRNA is read and translated into a specific sequence of amino acids. Choices B, C, and D are incorrect because mRNA does not unzip, expose nitrogen bases, pair with DNA bases, or pull free of the DNA strand in the cytoplasm. The primary function of mRNA in the cytoplasm is to serve as a template for protein synthesis by binding to ribosomes.
5. What helps the cell maintain its shape and allows it to adapt?
- A. Microfilaments
- B. Cytoplasm
- C. Cytoskeleton
- D. Centrioles
Correct answer: C
Rationale: The cytoskeleton is the correct answer. It provides structural support to the cell, helps maintain its shape, and enables it to adapt to different environments. Microfilaments are part of the cytoskeleton, but they alone do not encompass the entire cytoskeleton's functions. Cytoplasm is the fluid inside the cell where organelles are suspended and is not directly responsible for maintaining cell shape. Centrioles are involved in cell division and do not primarily contribute to maintaining the cell's shape and adaptation.
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