HESI A2 Biology Exams — HESI A2 Biology Practice Questions
1. Which is an example of the correct organizational hierarchy for a wolf?
Answer: B
DNA, blood cell, muscle tissue, heart, circulatory system, wolf
This sequence illustrates the correct organizational hierarchy for a wolf, progressing from the molecular level of DNA to the organism level represented by the wolf itself.
A) Muscle tissue, blood cell, DNA, organ, circulatory system, wolf
This option incorrectly orders the components, starting with muscle tissue rather than the foundational level of DNA. Additionally, it places organ and circulatory system after these components, disrupting the proper hierarchy.
B) DNA, blood cell, muscle tissue, heart, circulatory system, wolf
This choice correctly follows the organizational hierarchy, starting from DNA, which forms the basis of biological structure, followed by blood cells, muscle tissue, the heart, and the circulatory system, culminating at the organism level with the wolf.
C) Circulatory system, DNA, muscle tissue, blood cell, heart, wolf
This option is also incorrect as it begins with the circulatory system, which is a higher organizational level than DNA. The sequence disrupts the logical progression from molecular to systemic levels.
D) Blood cell, organ, circulatory system, muscle tissue, DNA, wolf
This choice fails to follow the appropriate hierarchy, as it starts with blood cells and incorrectly places DNA at a higher level than muscle tissue. The arrangement does not reflect the proper biological organization.
Conclusion
Option B is the only answer that accurately represents the hierarchical order of biological organization, beginning with DNA and culminating in the wolf as an organism. The other options misplace fundamental biological units or disrupt the logical progression, demonstrating a misunderstanding of the organizational structure in biological systems.
2. Why doesn't an antibiotic work for treating the flu symptoms in a patient?
Answer: B
An antibiotic is not effective against the flu virus.
Antibiotics target bacterial infections and have no effect on viral infections such as the flu. Therefore, using antibiotics to treat flu symptoms is ineffective because the flu is caused by a virus.
A) The antibiotic is for a different type of infection.
This option is incorrect because, while antibiotics are indeed designed to treat bacterial infections, the fundamental issue is that they do not work on viral infections like the flu. Thus, the specificity of the antibiotic is not the primary reason for its ineffectiveness against flu symptoms.
B) The antibiotic is not effective against the flu virus.
This statement accurately reflects the situation. Antibiotics are designed to combat bacterial pathogens and do not have any action against viruses, making them ineffective for treating flu symptoms, which are caused by the influenza virus.
C) The antibiotic is not administered in a sufficient dosage to combat the flu.
This option is misleading. The dosage of an antibiotic is irrelevant in this context since the primary issue is that antibiotics do not work against viral infections, regardless of the dosage. Therefore, this option does not correctly address why antibiotics are ineffective for flu.
D) None of the above
This option is incorrect as Option B provides a valid explanation for the ineffectiveness of antibiotics against flu symptoms. Therefore, stating that none of the provided options are correct does not hold true.
Conclusion
The correct answer is B, as it directly explains that antibiotics are not effective against viral infections like the flu. Options A and C misunderstand the nature of antibiotics and their target pathogens, while D fails to acknowledge the validity of the correct response. This highlights the importance of understanding the distinction between bacterial and viral infections in medical treatment.
3. What part of a light microscope is used to hold the slide in place?
Answer: D
The stage clips are used to hold the slide in place in a light microscope.
Stage clips are essential components of a light microscope that secure the slide, ensuring it remains stable during observation.
A) Base
The base of a light microscope serves as its foundation, providing stability and support for the entire structure. However, it does not directly hold the slide in place, making it an incorrect choice for this question.
B) Arm
The arm of a light microscope connects the base to the optical components and provides a handle for carrying the microscope. While it plays a crucial role in the overall structure, it does not function to hold the slide, thus rendering this option incorrect.
C) Rack stop
The rack stop is a mechanism that limits the movement of the stage, preventing damage to the microscope and the slide. However, it does not hold the slide in place, making this option incorrect as well.
D) Stage clips
Stage clips are specifically designed to secure the slide on the stage of the microscope. They ensure that the specimen is held firmly in place during observation, making this option the correct answer.
Conclusion
In summary, stage clips are vital for holding the slide securely in a light microscope, allowing for clear observation of the specimen. The other options, while important components of the microscope, do not serve the function of securing the slide, thereby confirming that D is the only correct answer.
4. Which type of cells possess a cell membrane?
Answer: C
Both prokaryotic and eukaryotic cells possess a cell membrane.
Both prokaryotic and eukaryotic cells have a cell membrane that serves as a barrier, regulating the movement of substances in and out of the cell.
A) Prokaryotic cells only
This option is incorrect because while prokaryotic cells do have a cell membrane, they are not the only type of cells that possess this structure. Eukaryotic cells also have cell membranes, making this statement incomplete.
B) Eukaryotic cells only
This option is also incorrect as it suggests that only eukaryotic cells have a cell membrane. However, prokaryotic cells, such as bacteria, also possess cell membranes, making this answer insufficient.
C) Both prokaryotic and eukaryotic cells
This option is correct since it acknowledges that both prokaryotic and eukaryotic cells possess a cell membrane. This membrane is essential for maintaining cellular integrity and facilitating communication with the external environment.
D) None of the above
This option is incorrect because it asserts that no cells possess a cell membrane, which is false. Both prokaryotic and eukaryotic cells indeed have cell membranes, making this statement inaccurate.
Conclusion
The correct answer is C because it accurately reflects the fact that both prokaryotic and eukaryotic cells possess a cell membrane, which is crucial for cellular function. All other options fail to recognize the presence of cell membranes in one or both cell types, thus leading to incorrect conclusions.
Answer: A
Epithelial cells are polarized.
Epithelial cells exhibit polarity, meaning they have distinct structural and functional regions. This characteristic is essential for their role in absorption, secretion, and protection.
A) Polarized
This option is correct because epithelial cells possess an apical surface, which faces the lumen or external environment, and a basal surface, which is attached to the underlying connective tissue. This polarization is crucial for their functions, such as selective absorption and secretion.
B) Neutral
This option is incorrect as it does not accurately describe epithelial cells. While the term "neutral" could refer to a lack of charge or activity, it fails to address the distinct structural features and functional specialization that epithelial cells possess, particularly their polarity.
C) Larger than other cells
This option is incorrect since epithelial cells are not necessarily larger than other cell types. In fact, they can vary significantly in size and shape depending on their specific function and location within the body, but they are not universally larger than other cells.
D) None of the above
This option is also incorrect because it suggests that epithelial cells do not possess any of the characteristics listed. Since option A accurately describes epithelial cells as polarized, this option cannot be correct.
Conclusion
The correct answer is A, as epithelial cells are defined by their polarized nature, which is critical for their various roles in the body. Options B, C, and D fail to accurately represent the defining characteristics of epithelial cells, further reinforcing that polarization is a key aspect of their identity and function.
6. Which of the following options best represents complementary base pairing in DNA?
Answer: D
A and T
Complementary base pairing in DNA is represented by the pairing of adenine (A) with thymine (T). This specific pairing is crucial for the structure and function of DNA, ensuring accurate replication and transcription.
A) A and G
This option is incorrect as guanine (G) does not pair with adenine (A). In DNA, A pairs specifically with T, while G pairs with cytosine (C). Thus, A and G do not represent complementary base pairing.
B) A and C
Adenine (A) does not pair with cytosine (C) in DNA. Instead, A pairs with thymine (T), and C pairs with guanine (G). Therefore, A and C do not represent complementary base pairing.
C) A and A
This option is incorrect because adenine (A) cannot pair with another adenine (A) in DNA. Complementary base pairing requires specific pairs, which for A is thymine (T). Thus, A and A do not represent the proper pairing.
D) A and T
Adenine (A) pairs with thymine (T) in DNA, making this option correct. This pairing is essential for maintaining the double helix structure of DNA and for the fidelity of genetic information transfer.
Conclusion
The correct answer is D, as adenine (A) and thymine (T) represent the fundamental complementary base pairing in DNA. All other options fail to demonstrate correct pairings according to the rules of nucleotide pairing, highlighting the importance of A-T pairing in the stability and function of DNA.
7. Which of the following is always true about molecules?
Answer: C
Molecules move from high concentration to low concentration without using energy.
Molecules typically move from areas of high concentration to areas of low concentration through a process known as diffusion, which does not require energy.
A) They can travel through all cell membranes
This statement is incorrect because not all molecules can pass through cell membranes. The permeability of a membrane depends on the size, charge, and polarity of the molecules, as well as the specific properties of the membrane itself.
B) They move from low concentration to high concentration without using energy
This option is incorrect because molecules do not naturally move from low to high concentration without the input of energy. Such movement requires active transport mechanisms, which utilize energy to move molecules against their concentration gradient.
C) They move from high concentration to low concentration without using energy
This statement is correct and reflects the fundamental principle of diffusion. Molecules will spontaneously move down their concentration gradient until equilibrium is reached, and this process does not require energy input.
D) They cannot move
This statement is false as it contradicts the basic principles of molecular motion. Molecules are always in motion due to thermal energy, and they can naturally diffuse within their environment unless otherwise restricted.
Conclusion
The correct answer is C, as it accurately describes the natural tendency of molecules to move from areas of high concentration to low concentration without the need for energy. Options A, B, and D are incorrect because they misrepresent the behavior of molecules in relation to cell membranes and the principles of concentration gradients.
8. How many different types of nucleotides are there in DNA?
Answer: C
There are four different types of nucleotides in DNA.
DNA is composed of four distinct types of nucleotides, which are the building blocks that form the genetic code. These nucleotides include adenine (A), thymine (T), cytosine (C), and guanine (G).
A) one
This option is incorrect because DNA is not made up of a single type of nucleotide. A single nucleotide cannot provide the diversity needed for genetic coding, which requires multiple types to create the sequences that encode information.
B) two
This option is also incorrect as it suggests that only two types of nucleotides exist in DNA. While there are pairs of nucleotides (A with T and C with G), the total number of unique nucleotide types is four, not two.
C) four
This option is correct because DNA consists of four unique nucleotides: adenine, thymine, cytosine, and guanine. Each of these nucleotides plays a crucial role in the structure and function of DNA, allowing for the complex coding of genetic information.
D) eight
This option is incorrect as it overestimates the number of nucleotide types in DNA. While DNA molecules may contain millions of nucleotides, there are only four distinct types that combine in various sequences to form the genetic material.
Conclusion
The correct answer is four, as DNA is made up of four different types of nucleotides essential for genetic encoding. All other options fail because they either underestimate or misrepresent the basic components of DNA, which are critical for understanding its structure and function.
9. In the human life cycle, only sperm and eggs have which number of chromosomes?
Answer: D
Sperm and eggs have haploid chromosomes.
In the human life cycle, sperm and eggs contain haploid chromosomes, which means they have one set of chromosomes (23 in humans), half the number found in diploid cells.
A) Diploid
Diploid cells contain two sets of chromosomes, one from each parent, totaling 46 chromosomes in humans. This option is incorrect because sperm and eggs do not have diploid numbers; they are formed through meiosis, which reduces the chromosome number to haploid.
B) Polyploid
Polyploid cells have more than two sets of chromosomes. This option is not applicable to human sperm and eggs, as they do not possess multiple sets of chromosomes but rather a single set, making this choice incorrect.
C) Monoploid
Monoploid refers to cells with only one complete set of chromosomes, which is similar in definition to haploid. However, the term is less commonly used in the context of human gametes. While it could be argued that monoploid is technically correct, haploid is the more accurate and widely accepted term for describing the chromosome number in sperm and eggs.
D) Haploid
Haploid is the correct term for sperm and eggs, which contain a single set of chromosomes (23 chromosomes in humans). This is essential for sexual reproduction, as it allows for the restoration of the diploid number when sperm and egg fuse during fertilization.
Conclusion
The correct answer is haploid, as it accurately describes the chromosome composition of human sperm and eggs. All other options fail to correctly represent the number of chromosomes present in these gametes, which are crucial for maintaining genetic diversity and stability in the human life cycle.
10. Why doesn't an antibiotic work for treating flu symptoms in a patient?
Answer: B
An antibiotic is not effective in treating viral infections like the flu.
Antibiotics are designed to treat bacterial infections, and the flu is caused by a virus. Therefore, antibiotics do not work against the influenza virus, making this option the correct explanation.
A) The antibiotic is for a different type of infection, not the flu.
While it is true that antibiotics target bacterial infections, this option does not directly address the nature of the flu virus. The flu specifically is not treated by antibiotics because it is not a bacterial infection, which makes this option partially correct but less precise than the correct answer.
B) The antibiotic is not effective in treating viral infections like the flu.
This statement accurately reflects the fundamental reason antibiotics fail to treat flu symptoms. Since the flu is caused by a virus, antibiotics have no effect on viral infections, confirming this as the correct choice.
C) The antibiotic is not administered in a sufficient dosage to combat the flu.
This option suggests that dosage is a factor in antibiotic effectiveness against the flu. However, the issue lies not in the dosage but in the fact that antibiotics do not work against viral infections at all, rendering this choice incorrect.
D) None of the above
This choice implies that all previous statements are incorrect. However, since option B correctly identifies the reason antibiotics do not work for the flu, this option is inaccurate.
Conclusion
The correct answer, option B, clearly explains that antibiotics are ineffective against viral infections such as the flu. The other options either misinterpret the role of antibiotics or fail to address the viral nature of the flu, making them incorrect. Understanding the distinction between bacterial and viral infections is crucial for appropriate treatment decisions.