Free Biology practice for HESI A2 Practice Test Biology (HESI A2). Answer 38 nursing exam-style questions with rationales, exam mode, and progress tracking on N
Why is DNA important for metabolic activities of the cell?
Select the best answer.
Explanation:
The correct answer is A. DNA plays a crucial role in metabolic activities by controlling the synthesis of enzymes. Enzymes are the biological catalysts that regulate and facilitate metabolic reactions within the cell. Choice B is incorrect because DNA is not involved in stabilizing the cell wall; that role is usually associated with other components like the cell membrane. Choice C is incorrect as cell division is primarily regulated by different processes and molecules, not directly by DNA. Choice D is incorrect because DNA is not related to preventing the diffusion of nutrients; instead, it is involved in coding for proteins that aid in various cellular functions.
Which gives the order of four taxonomic categories from least to most specific?
Select the best answer.
Explanation:
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'.
Which component is not found in the nucleotide of DNA?
Select the best answer.
Explanation:
Citric acid is not found in the nucleotide of DNA. A DNA nucleotide is composed of a simple sugar (deoxyribose), a nitrogen base (adenine, thymine, cytosine, or guanine), and a phosphate group. Citric acid is not part of DNA nucleotides; instead, it is involved in the citric acid cycle of cellular respiration. Choices A, B, and C are essential components of DNA nucleotides, making them incorrect answers.
Which bacteria are spherical in shape?
Select the best answer.
Explanation:
The correct answer is D, Cocci. Bacteria that are spherical in shape are known as cocci. They can be found in various arrangements such as clusters, chains, or pairs. Examples of cocci bacteria include Staphylococcus aureus and Streptococcus pneumoniae. Choice A, Clostridia, consists of rod-shaped bacteria. Choice B, Bacilli, refers to rod-shaped bacteria as well. Choice C, Spirilla, are spiral-shaped bacteria, not spherical.
What is the most important component of the cell, contributing to protection, communication, and the passage of substances?
Select the best answer.
Explanation:
The cell membrane is the correct answer. It is the most important component of the cell as it provides protection, facilitates communication, and regulates the passage of substances in and out of the cell. The cytoplasm (Choice A) is the gel-like substance within the cell that holds organelles, but it is not primarily responsible for the functions mentioned in the question. The cytoskeleton (Choice C) provides structural support to the cell but is not directly involved in protection, communication, or substance passage. Vacuoles (Choice D) are responsible for storage and maintaining turgor pressure but do not play a primary role in the functions specified in the question.
Which of the following is true of the Krebs cycle?
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Explanation:
The Krebs cycle, also known as the citric acid cycle, involves a series of redox reactions that occur in the mitochondria. The cycle begins with the oxidation of acetyl CoA, which is derived from the breakdown of sugars produced during glycolysis. These sugars are broken down further in the Krebs cycle to produce ATP and reduce electron carriers such as NADH and FADH2. The cycle does not involve proteins produced during glycolysis. Protons are not passed along a gradient to produce ATP directly in the Krebs cycle; rather, they are used in the electron transport chain to generate ATP. The Krebs cycle is not known as the glycolic acid cycle; glycolysis is the metabolic pathway that produces pyruvate from glucose.
Which of the following is an example of human error in an experiment?
Select the best answer.
Explanation:
Contaminating a sterile sample by breathing on it is an example of human error in an experiment because it involves an action directly caused by the researcher that compromises the integrity of the sample. Breathing on a sterile sample introduces external contaminants that can affect the results. Choices A, C, and D involve factors not directly under the researcher's control or are technical errors that do not involve direct human actions.
What happens during anaphase?
Select the best answer.
Explanation:
During anaphase, the sister chromatids, joined at the centromere, separate and move towards opposite ends of the spindle apparatus. This movement ensures that each daughter cell receives an identical set of chromosomes. Choice B is incorrect as the disintegration of the nuclear membrane and nucleoli occurs during prophase. Choice C is incorrect as chromatids align at the center of the spindle during metaphase, not anaphase. Choice D is incorrect as the formation of the nuclear membrane and nucleoli occurs during telophase, not anaphase.
What is the binding membrane of an animal cell called?
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Explanation:
The correct answer is D: Plasma membrane. The plasma membrane surrounds the cell and acts as an interface between the living interior of the cell and the nonliving exterior. It plays a vital role in maintaining the cell's integrity, regulating the passage of substances in and out of the cell, and facilitating communication with other cells. Choices A, B, and C are incorrect because the term 'plasma membrane' specifically refers to the binding membrane of an animal cell, distinguishing it from other types of membranes or coatings found in cells.
Which is true of the term Phenotype?
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Explanation:
The term "phenotype" refers to the observable characteristics or traits of an organism, which are determined by a combination of genotype (genetic makeup), epigenetic factors (modifications to gene expression), and environmental factors (external influences and experiences). Genotype, epigenetic factors, and environmental factors all play a role in determining an individual's phenotype, making option D the correct statement. Options A, B, and C are incorrect because the phenotype is not the genetic code, the phenotype does not determine the genotype, and it is the genotype that influences the phenotype, not the other way around.
Which of the following shows how information is transformed to make a protein?
Select the best answer.
Explanation:
The correct sequence of events for protein synthesis is that DNA is transcribed into RNA, which is then translated into a protein. This process is known as the central dogma of molecular biology. In this sequence, DNA serves as the template for RNA synthesis (transcription), and the RNA serves as the template for protein synthesis (translation). Choice B is incorrect as genes are segments of DNA that code for proteins, and chromosomes are structures that contain DNA. Choice C is incorrect as ATP is an energy molecule and amino acids are the building blocks of proteins, but they are not directly involved in the synthesis process. Choice D is incorrect because RNA is first transcribed from DNA and then used as a template to produce proteins.
Where is the slide typically placed on a microscope?
Select the best answer.
Explanation:
The slide is typically placed on the stage of a microscope. The stage is the platform where the slide containing the specimen is positioned for viewing. The eyepiece is where you look through to view the specimen, the focus knob is used to sharpen the image, and the objective lens is responsible for magnification. Therefore, the correct answer is the stage.
Cytosine and thymine are known as:
Select the best answer.
Explanation:
Cytosine and thymine are known as pyrimidines because they have a single carbon ring structure. Purines, on the other hand, have a double-ring structure. Choice A ('Purines') is incorrect because purines have a double-ring structure, unlike cytosine and thymine. Choice C ('Both') is incorrect as it implies they are both purines and pyrimidines, which is not true. Choice D ('None of the above') is incorrect because cytosine and thymine are indeed pyrimidines.
Why do high-salt content foods not require refrigeration to prevent spoilage?
Select the best answer.
Explanation:
Osmosis is the natural process that prevents high-salt content foods from spoiling without the need for refrigeration. Osmosis involves the movement of water across a semi-permeable membrane from an area of lower solute concentration (water) to an area of higher solute concentration (salt). In high-salt content foods, the salt acts as a preservative by drawing moisture out of bacteria or other microorganisms, making it difficult for them to survive and spoil the food. This process helps in preserving the food and preventing spoilage even without refrigeration. Choices B, C, and D are incorrect because they do not involve the specific mechanism of water movement in response to the salt concentration in high-salt content foods.
What is the function of water in photosynthesis?
Select the best answer.
Explanation:
The correct answer is C: 'Supply electrons in the light reactions.' In photosynthesis, water is split during the light reactions of photosynthesis, releasing electrons that are used in the formation of ATP and NADPH, crucial for the synthesis of glucose. Choice A is incorrect because water does not combine with carbon dioxide in photosynthesis. Choice B is incorrect as water does not absorb light energy directly. Choice D is incorrect because the transportation of hydrogen ions mainly occurs in the electron transport chain, which is part of the light reactions, not the dark reactions.
Why is the nucleus important in a cell?
Select the best answer.
Explanation:
The nucleus is important in a cell because it stores the DNA, which contains the genetic information necessary for the cell's function and replication. This genetic material controls the cell's activities and characteristics. Choices B, C, and D are incorrect because supporting the cell, making proteins, and producing energy are functions typically associated with other cell organelles like the cytoskeleton, ribosomes, and mitochondria, respectively.
Which organelle is responsible for making proteins?
Select the best answer.
Explanation:
Ribosomes are the organelles responsible for protein synthesis within the cell. They are the sites where amino acids are linked together to form proteins based on the instructions carried by mRNA (messenger RNA). Ribosomes can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum, and they play a crucial role in translating genetic information into proteins. Chloroplasts are responsible for photosynthesis, lysosomes are involved in digestion and waste removal, and mitochondria are known as the powerhouse of the cell responsible for energy production through cellular respiration. Therefore, the ribosome is the correct organelle responsible for making proteins.
What is the purpose of the mitochondria?
Select the best answer.
Explanation:
The correct answer is B: Create energy. The primary purpose of the mitochondria is to generate energy for the cell. Mitochondria are known as the 'powerhouses' of the cell because they produce ATP (adenosine triphosphate), which is the energy currency used by cells to carry out various functions and processes. Choice A is incorrect as the mitochondria do not control the cell but rather produce energy. Choice C is incorrect as protein synthesis primarily occurs in the ribosomes. Choice D is incorrect as packaging waste for removal is a function associated with lysosomes, not mitochondria.
How do animal cells divide?
Select the best answer.
Explanation:
Animal cells divide through a contractile ring made of actin and myosin filaments. The ring contracts, pinching the cell membrane in the middle to form two daughter cells. Plant cells use a cell plate due to their rigid cell walls, making choices B and C incorrect. Choice D is incorrect as animal cells do use the contractile ring method for division.
Which structure controls the passage of substances into and out of the cell?
Select the best answer.
Explanation:
The correct answer is the Cell Membrane. The cell membrane acts as a barrier that controls the passage of substances into and out of the cell. It is selectively permeable, allowing only certain molecules to pass through. Vacuole (Choice A), Nuclear Membrane (Choice C), and Cytoplasm (Choice D) do not primarily regulate the passage of substances in and out of the cell. Vacuoles are responsible for storage, the nuclear membrane surrounds the nucleus providing protection, and the cytoplasm is the fluid where organelles are suspended.
What is the function of decomposition in the carbon cycle?
Select the best answer.
Explanation:
The correct answer is C: 'To release carbon dioxide.' Decomposition in the carbon cycle involves breaking down dead organic matter into simpler substances. During this process, carbon is released in the form of carbon dioxide back into the atmosphere. This release of carbon dioxide is essential for recycling carbon and making it available for use by living organisms. Choices A, B, and D are incorrect because decomposition does not produce light energy, convert carbon to fuel, or store food for consumers; its primary role is to recycle carbon through the release of carbon dioxide.
What is the main function of the cell membrane?
Select the best answer.
Explanation:
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.
Which type of passive transport uses proteins that change shape to move a target molecule through the membrane?
Select the best answer.
Explanation:
The correct answer is B: Carrier proteins. Carrier proteins are involved in facilitated diffusion, a type of passive transport where specific target molecules are moved across the membrane with the help of proteins that change shape. These carrier proteins bind to the target molecule on one side of the membrane, undergo a conformational change, and then release the molecule on the other side. This process is crucial for the selective transport of certain molecules that cannot pass through the membrane by simple diffusion. Choices A and C are incorrect because diffusion and channel proteins do not involve proteins that change shape to transport target molecules selectively. Choice D is incorrect as carrier proteins fit the description provided in the question.
What is the term for the breakdown of glycogen into glucose subunits?
Select the best answer.
Explanation:
Hydrolysis is the term used to describe the breakdown of large molecules into smaller units by adding water. In the case of glycogen being broken down into glucose subunits, this process involves the addition of water molecules to break the glycosidic bonds between glucose molecules, resulting in the release of individual glucose subunits. This process is crucial for providing cells with a source of energy when needed. Choice B, Reduction, refers to a chemical reaction involving a gain of electrons or a decrease in oxidation state, not the breakdown of glycogen into glucose subunits. Choice C, Metabolism, is a broad term encompassing all biochemical processes in an organism, including anabolism and catabolism, but does not specifically describe the breakdown of glycogen into glucose subunits. Choice D, Transpiration, is the process of water movement through a plant and is not related to the breakdown of glycogen into glucose subunits.
What is the term for the movement of ions and other molecular substances across cell membranes without the need for energy?
Select the best answer.
Explanation:
Passive transport refers to the movement of substances across cell membranes without the need for energy input. In contrast, active transport, choice A, requires energy to move substances against their concentration gradient. Diffusion, choice C, is a type of passive transport where substances move from an area of high concentration to low concentration. Osmosis, choice D, specifically refers to the movement of water molecules across a selectively permeable membrane.
What type of tissue is fat?
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Explanation:
Fat is a type of loose connective tissue known as adipose tissue. Adipose tissue primarily functions to store energy and provide cushioning and insulation for organs. While muscle tissue is responsible for movement, nervous tissue transmits nerve impulses, and epithelial tissue covers and protects body surfaces, fat specifically falls under the category of connective tissue.
Beeswax is an example of what kind of molecule?
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Explanation:
Beeswax is primarily composed of esters of long-chain aliphatic alcohols and fatty acids, making it a type of lipid. Lipids are a diverse group of molecules that are hydrophobic in nature and have important functions in energy storage, signaling, and forming cellular membranes. Beeswax's chemical composition and properties categorize it as a lipid rather than a carbohydrate, protein, or nucleic acid. Carbohydrates are composed of sugars, proteins are made up of amino acids, and nucleic acids consist of nucleotides; none of which match the chemical composition of beeswax.
What is the primary function of the endoplasmic reticulum in a cell?
Select the best answer.
Explanation:
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.
Which of these is not an example of a lipid?
Select the best answer.
Explanation:
Honey is not an example of a lipid because lipids are fat-related molecules that are insoluble in water, while honey is a natural sweet substance made by bees and primarily consists of sugars such as glucose and fructose. Butter, wax, and canola oil are examples of lipids as they are all composed of fat-related molecules that do not dissolve in water.
___________ is a symbiotic relationship in which one organism benefits and the other is not affected.
Select the best answer.
Explanation:
The correct answer is 'Commensalism.' In commensalism, one organism benefits from the relationship while the other is neither helped nor harmed. This type of symbiotic relationship is characterized by one organism deriving a benefit, such as food or shelter, without impacting the other organism in any significant way. Choice A, 'Mutualism,' is a symbiotic relationship in which both organisms benefit. Choice B, 'Parasitism,' is a symbiotic relationship in which one organism benefits at the expense of the other. Choice D, 'Competition,' refers to a relationship in which organisms compete for limited resources, with both being affected in terms of access to resources.
Which of the following is not true about enzymes?
Select the best answer.
Explanation:
Enzymes lower the activation energy needed for a reaction to occur, not raise it. By lowering the activation energy, enzymes facilitate reactions, making them occur more easily and rapidly. Choice A is correct as enzymes indeed catalyze reactions. Choice C is correct as enzymes have specific active sites where substrates bind. Choice D is correct as enzymes are commonly proteins, although some RNA molecules also exhibit catalytic properties.
The two catabolic pathways that lead to cellular energy production are:
Select the best answer.
Explanation:
The correct answer is D: cellular respiration and fermentation. Cellular respiration involves the breakdown of glucose in the presence of oxygen to produce ATP, which is the primary source of energy for cells. Fermentation, on the other hand, occurs in the absence of oxygen and produces ATP through glycolysis followed by specific fermentation pathways. Choices A, B, and C are incorrect. Protein synthesis is a biosynthetic process, not a catabolic pathway for energy production. Glycolysis is a common step in both cellular respiration and fermentation, so it is not a pair of distinct catabolic pathways. Therefore, the most accurate pairing of catabolic pathways for cellular energy production is cellular respiration and fermentation.
A cell from heart muscle would more than likely contain an unusually high proportion of which of the following?
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Explanation:
A cell from heart muscle would more than likely contain an unusually high proportion of mitochondria because the heart muscle requires a significant amount of energy to function properly. Mitochondria are the powerhouse of the cell and are responsible for producing energy in the form of ATP through cellular respiration. Therefore, to meet the high energy demands of the heart muscle, it would need a higher concentration of mitochondria compared to other cell types. Choices A, C, and D are incorrect because while lysosomes, mRNA, and ribosomes are essential components of a cell, they do not play as direct a role in meeting the high energy demands of heart muscle as mitochondria do.
What is the effect of the Earth's rotation on the atmosphere and on all objects on the Earth's surface?
Select the best answer.
Explanation:
The Coriolis effect is the effect of the Earth's rotation on the atmosphere and on all objects on the Earth's surface. It causes moving objects and currents to be deflected to the right in the northern hemisphere and to the left in the southern hemisphere. This deflection is a result of the rotation of the Earth and plays a crucial role in influencing weather patterns and ocean currents around the globe. The other choices provided are incorrect. The Corona effect is related to the Sun's atmosphere, the Archimedes effect involves buoyancy in fluids, and the tidal effect is associated with the gravitational forces between the Earth, the Moon, and the Sun.
In an example of a male with hemophilia and a female carrier, what ratio of the offspring are predicted neither to carry nor to manifest the disease?
Select the best answer.
Explanation:
In this scenario, the male offspring will inherit the Y chromosome from the father and the X chromosome from the carrier mother. As a result, they will not have the hemophilia gene. The female offspring will inherit one X chromosome from the mother, which does not carry the hemophilia gene, and one X chromosome from the father, which does not exist due to the Y chromosome. Therefore, all female offspring will not carry or manifest hemophilia, resulting in a ratio of 2 females to 1 male. Choice A is incorrect because it does not account for the female offspring. Choices B and C are incorrect as they do not reflect the correct ratio based on the inheritance pattern of hemophilia.
Imagine that two parents both carry the recessive gene for cystic fibrosis. Any homozygous recessive offspring will manifest the disease. What percentage of the offspring is predicted to be carriers but not manifest the disease?
Select the best answer.
Explanation:
When both parents carry the recessive gene for cystic fibrosis (homozygous recessive), there is a 25% chance for each offspring to inherit two recessive alleles and, therefore, manifest the disease. There is also a 50% chance for each offspring to inherit one recessive allele and one dominant allele, making them carriers of the disease but not manifest it. Therefore, 25% of the offspring are predicted to be carriers but not manifest the disease. Choice A (0%) is incorrect because there is a portion of offspring that will be carriers. Choice C (50%) is incorrect as this percentage corresponds to carriers who will not manifest the disease. Choice D (100%) is incorrect as not all offspring will be carriers and not manifest the disease.
Two organisms live in a relationship from which both benefit. What is this called?
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Explanation:
Mutualism is a type of symbiotic relationship between two organisms in which both parties benefit from the association. It is a mutually beneficial interaction where both organisms gain something valuable, such as food, protection, or some other resource. This contrasts with parasitism, where one organism benefits at the expense of the other, commensalism, where one organism benefits while the other is unaffected, and competition, where both organisms are negatively affected by their interaction.
Tundra, savannas, grasslands, deserts, and rainforests are examples of what?
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Explanation:
Tundra, savannas, grasslands, deserts, and rainforests are examples of biomes. A biome is a large geographical area with similar climatic conditions and distinct flora and fauna. Each biome has its unique characteristics, such as temperature, precipitation levels, and types of vegetation, which define the ecosystem within that region. Biomasses refer to the total mass of living organisms in a given area, biospheres are the global ecological system integrating all living beings and their relationships, and biodiversity represents the variety of life forms in a specific habitat.
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