Free HESI A2 Biology practice for HESI A2 Biology Version 2 (HESI A2). Answer 25 nursing exam-style questions with rationales, exam mode, and progress tracking
Aerobic respiration occurs in the presence of what necessary molecule?
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Explanation:
Oxygen is essential for aerobic respiration as it acts as the final electron acceptor in the electron transport chain, producing ATP
The cellular membrane consists of a bilayer of which substances?
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Explanation:
The cellular membrane is primarily composed of a phospholipid bilayer, forming the structure that regulates entry and exit.
Which cellular appendage enables cells to move through their environments?
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Explanation:
"Flagellum" is a whip-like appendage that allows certain cells to move through their environment.
Which disease is caused by a bacterium?
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Explanation:
Strep throat is caused by the bacterium Streptococcus pyogenes. Unlike mumps, which is a viral infection, AIDS caused by the HIV virus, and the common cold usually caused by rhinoviruses, strep throat is specifically a bacterial infection that can be treated with antibiotics.
What cellular appendage enables cells to move through their environments?
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Explanation:
The flagellum is a whip-like appendage found in certain cells like sperm cells and some bacteria, enabling them to move through their environments. It plays a crucial role in locomotion by allowing cells to swim or propel themselves in liquids, aiding in their movement and navigation.
What process do sex cells undergo to reproduce?
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Explanation:
Sex cells, also known as gametes, undergo the process of meiosis to reproduce. Meiosis is a specialized type of cell division that reduces the chromosome number by half, resulting in the formation of four genetically diverse haploid cells from a diploid cell. This reduction is essential for sexual reproduction to ensure genetic diversity in the offspring.
How does the concentration of solutes in a hypertonic solution compare to the cell's?
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Explanation:
In a hypertonic solution, the concentration of solutes is higher compared to the cell's interior. This causes water to move out of the cell to balance the solute concentrations, resulting in the cell shrinking. Therefore, the correct answer is that the solute concentration is higher in a hypertonic solution than inside the cell.
What is the typical result of mitosis in humans?
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Explanation:
During mitosis, a cell divides to produce two identical daughter cells that are genetically identical to the parent cell. These daughter cells are diploid, meaning they contain the full set of chromosomes. Therefore, the typical result of mitosis in humans is the formation of two diploid cells (Choice A). Choices B, C, and D are incorrect as mitosis results in the production of diploid cells, not haploid cells, and typically, it results in two daughter cells, not four.
How does water affect the temperature of a living thing?
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Explanation:
Water has a high specific heat capacity, meaning it can absorb and release a large amount of heat with minimal temperature change. This property allows water to regulate and stabilize the temperature of living things by absorbing excess heat or providing warmth when releasing stored heat. Therefore, choice B, 'Water helps keep temperature stable,' is the correct answer.
Which of the following is not a product of the Krebs cycle?
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Explanation:
The correct answer is B, 'oxygen.' The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that produce energy-rich molecules like ATP, carbon dioxide, and energy carriers such as NADH and FADH2. Oxygen is not a direct product of the Krebs cycle but is essential for the electron transport chain, which follows the Krebs cycle and is where oxygen is used as the final electron acceptor.
What type of bond connects sugar and phosphate in DNA?
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Explanation:
The correct answer is covalent (Choice C). In DNA, the bond connecting the sugar and phosphate groups is a phosphodiester bond, which is a type of covalent bond. Covalent bonds involve the sharing of electrons between atoms, forming strong and stable connections. Hydrogen bonds are important in DNA structure but are not the primary bond connecting sugar and phosphate. Ionic bonds involve the transfer of electrons between atoms, which is not the case in sugar-phosphate bonds. 'Overt' is not a term used to describe the bond between sugar and phosphate in DNA.
What is the second part of an organism's scientific name?
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Explanation:
The correct answer is A: species. In binomial nomenclature, an organism's scientific name consists of two parts: the genus name (first part) and the species name (second part). The second part, the species name, is essential for precisely identifying a specific organism within the genus. Therefore, when determining an organism's scientific name, the second part is the species.
How are lipids different from other organic molecules?
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Explanation:
Lipids are different from other organic molecules because they are not water-soluble, unlike carbohydrates and proteins. This property is due to their hydrophobic nature, which makes them insoluble in water but soluble in nonpolar solvents. Lipids play essential roles in energy storage, insulation, and cell membrane structure, making them distinct from other organic molecules. The statement 'They are indivisible' (Choice A) is not accurate as lipids can be broken down into fatty acids and glycerol. Choice C, 'They contain zinc,' is incorrect as lipids do not necessarily contain zinc. Choice D, 'They form long proteins,' is inaccurate as lipids do not form proteins; proteins are formed from amino acids.
Which of the following is not found within a bacterial cell?
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Explanation:
Mitochondria are organelles found in eukaryotic cells, not in bacterial cells. Bacterial cells lack membrane-bound organelles like mitochondria. Choices B, C, and D are all components that can be found within a bacterial cell. DNA is the genetic material that carries the instructions for cell function, vesicles are involved in transport and storage of substances, and ribosomes are responsible for protein synthesis in bacterial cells.
Which cell organelle functions to transport materials from the endoplasmic reticulum throughout the cell?
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Explanation:
The correct answer is B, Golgi apparatus. The Golgi apparatus plays a crucial role in modifying, sorting, and packaging proteins and lipids that it receives from the endoplasmic reticulum. After processing these materials, the Golgi apparatus transports them to other parts of the cell or outside the cell. It acts as a distribution center within the cell, ensuring that different molecules reach their correct destinations for various cellular functions.
Which of the following organelles is responsible for producing cell energy?
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Explanation:
The correct answer is A: Mitochondrion and chloroplast. Mitochondria are known as the powerhouse of the cell as they produce the majority of a cell's energy in the form of ATP (adenosine triphosphate) through aerobic respiration. Chloroplasts, found in plant cells, are responsible for photosynthesis, a process that converts light energy into chemical energy in the form of glucose. Therefore, both mitochondria and chloroplasts play crucial roles in energy production in cells.
Which cell component is responsible for protection, communication, and regulating the passage of substances into and out of the cell?
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Explanation:
The cell membrane is responsible for protecting the cell, facilitating communication with other cells, and regulating the passage of substances into and out of the cell. It acts as a barrier that controls the movement of molecules, ions, and other substances, maintaining the cell's internal environment and enabling cellular interactions with the external environment. The nucleus contains genetic material and is not primarily involved in protection, communication, or regulating the passage of substances. The endoplasmic reticulum is involved in protein synthesis and lipid metabolism. The cytoplasm is a gel-like substance that fills the cell and is not directly responsible for protection, communication, or regulating substance passage.
Which of the following is a protein?
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Explanation:
Hemoglobin is the correct answer as it is a protein. Proteins are large, complex molecules composed of amino acids that are essential for various structural and functional roles in the body. Hemoglobin, specifically, is a protein found in red blood cells and is responsible for carrying oxygen from the lungs to different parts of the body, highlighting its crucial role in oxygen transportation.
Which of the following structures is not directly involved in translation?
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Explanation:
Translation is the process of protein synthesis where mRNA is decoded to produce a specific polypeptide chain. tRNA brings amino acids to the ribosome, and the ribosome is the site where translation occurs. DNA is not directly involved in translation; instead, it serves as the genetic material that stores the instructions for protein synthesis but does not play a direct role in the protein synthesis machinery.
Which of the following is necessary for cell diffusion?
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Explanation:
Water is necessary for cell diffusion because it serves as the medium through which particles move across cell membranes. Diffusion is the passive movement of particles from an area of higher concentration to an area of lower concentration, and water plays a crucial role in facilitating this process by dissolving molecules and allowing them to move freely. Membranes provide the barrier for diffusion to occur, ATP is not directly involved in the process of diffusion, and a gradient is the difference in concentration that drives diffusion but is not a necessary component for diffusion itself.
How many different types of nucleotides are there in DNA?
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Explanation:
The correct answer is C: four. DNA is composed of four different types of nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). These nucleotides pair specifically (A with T and C with G) to form the double-stranded DNA structure.
Which of the following cell types lacks a nucleus?
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Explanation:
The correct answer is red blood cell (choice B). Red blood cells, also known as erythrocytes, lack a nucleus at maturity in humans. The absence of a nucleus allows these cells to carry oxygen more efficiently by maximizing space for hemoglobin, the oxygen-carrying protein. Platelets (choice A), white blood cells (choice C), and phagocytes (choice D) all have nuclei. Platelets are involved in blood clotting, white blood cells are part of the immune system, and phagocytes specialize in engulfing and digesting cellular debris and pathogens.
Which hormone is produced by the pineal gland?
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Explanation:
The correct answer is melatonin (Choice C). The pineal gland is responsible for producing melatonin, a hormone that regulates sleep-wake cycles. Insulin (Choice A) is produced by the pancreas and regulates blood sugar levels. Testosterone (Choice B) is primarily produced by the testes in males and in smaller amounts by the ovaries in females. Epinephrine (Choice D) is produced by the adrenal glands and is involved in the body's fight-or-flight response.
Which organelle is responsible for organizing protein synthesis?
Select the best answer.
Explanation:
The organelle responsible for organizing protein synthesis is the ribosome. Ribosomes are the cellular structures where proteins are synthesized or produced. They can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum. Mitochondria are known as the powerhouse of the cell, responsible for generating energy through cellular respiration. The nucleus is the control center of the cell, housing the genetic material and controlling cell activities. Vacuoles are responsible for storing various substances within the cell and maintaining turgor pressure.
During which phase is the chromosome number reduced from diploid to haploid?
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Explanation:
The correct answer is meiosis I. Meiosis is a specialized cell division process that occurs in sexually reproducing organisms to produce gametes (sperm and egg). In meiosis I, the chromosome number is reduced from diploid (2n) to haploid (n) by separating homologous chromosomes. This reduction in chromosome number is crucial for maintaining the correct chromosome count in sexually reproducing organisms and ensuring genetic diversity in offspring.
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