Free HESI A2 Biology practice for HESI A2 Biology Version 6 (HESI A2). Answer 24 nursing exam-style questions with rationales, exam mode, and progress tracking
Which of the following statements is false regarding cell structures?
Select the best answer.
Explanation:
The statement in option B is false because animal cells do not use chloroplasts to gain energy. Chloroplasts are found in plant cells and are responsible for photosynthesis, a process where plants convert light energy into chemical energy. Animal cells rely on mitochondria to produce energy through cellular respiration. Options A and C are true statements as lysosomes are responsible for breaking down old cells in animal cells, and plant cells have a cell wall to provide structural support.
Which of the following is always true about molecules?
Select the best answer.
Explanation:
The correct answer is C: 'They move from high concentration to low concentration without using energy.' This statement aligns with the concept of passive transport, where molecules naturally move from areas of higher concentration to lower concentration to reach equilibrium. This process does not require energy input. Option A is incorrect because not all molecules can freely pass through all cell membranes due to factors like size and charge. Option B describes active transport, which involves the movement of molecules against their concentration gradient, requiring energy. Option D is incorrect as molecules are in constant motion.
Which type of passive transport uses proteins that change shape to move a target molecule through the membrane?
Select the best answer.
Explanation:
Carrier proteins are involved in facilitated diffusion, a type of passive transport where molecules move across the cell membrane with the help of specific carrier proteins that change shape to transport the molecules across. Channel proteins, on the other hand, form pores or channels to allow specific molecules to pass through the membrane via passive transport. Diffusion, while a passive transport process, does not involve proteins changing shape to facilitate the movement of molecules.
Phenotype refers to the.................... of an individual.
Select the best answer.
Explanation:
Phenotype refers to the observable physical characteristics of an individual, such as hair color, eye color, and height. It is the result of the interaction between an individual's genetic makeup (genotype) and environmental influences. Therefore, the correct answer is B, 'Actual physical appearance.' The term 'genetic makeup' (Choice A) refers to genotype, which is the actual set of genes an individual carries. 'Recessive alleles' (Choice C) are specific forms of genes that are masked by dominant alleles in heterozygous individuals and do not directly define the phenotype. 'None of the above' (Choice D) is incorrect as phenotype does refer to something among the given choices, which is the actual physical appearance.
When the genotype consists of a dominant and a recessive allele, the phenotype will be like the....................allele.
Select the best answer.
Explanation:
When an individual possesses a genotype with both a dominant and a recessive allele, the dominant allele will dictate the phenotype. Dominant alleles are expressed over recessive alleles in heterozygous individuals, leading to the phenotype resembling the dominant allele's characteristics.
In a population of dogs, fur color is determined by two alleles: black (B) and tan (b). The black allele shows complete dominance. If a dog has tan fur, what is its genotype?
Select the best answer.
Explanation:
When a dog has tan fur, it indicates that it has two recessive alleles for tan fur, which is represented as bb. Since black (B) is dominant over tan (b), the genotype of a dog with tan fur must be bb.
Based on the information provided, what would be the phenotype if the offspring is Bb?
Select the best answer.
Explanation:
In genetics, when the offspring is Bb, it represents a heterozygous genotype with 'B' denoting black color. In this scenario, 'black' would be the phenotype displayed by the offspring. The dominant allele 'B' for black color would mask the recessive allele 'b,' resulting in the expression of the black phenotype.
Which of the following is the best example of a hypothesis?
Select the best answer.
Explanation:
A hypothesis is a testable statement that predicts the outcome of an experiment based on observations or research. Option D is the best example of a hypothesis as it presents a clear cause-and-effect relationship that can be tested through an experiment. Options A, B, and C do not provide a clear prediction or testable statement, making them weaker examples of hypotheses. In contrast, option D clearly states the expected outcome of exposing a plant to red light, allowing for a specific experiment to test this hypothesis.
Tonicity refers to the movement of:
Select the best answer.
Explanation:
Tonicity is a term used to describe the relative concentration of solutes inside and outside of a cell. When a solution is hypertonic, it has a higher concentration of solutes outside the cell, causing water to move out of the cell. When a solution is hypotonic, it has a lower concentration of solutes outside the cell, causing water to move into the cell. Therefore, tonicity primarily affects the movement of water across a cell membrane.
What will happen to a hard-boiled egg if placed in a beaker of saltwater?
Select the best answer.
Explanation:
When a hard-boiled egg is placed in a beaker of saltwater, a hypertonic solution, water will move out of the egg through osmosis. The saltwater's higher solute concentration causes water to leave the egg in an attempt to balance the concentrations, resulting in the egg losing water and shrinking, leading to it shriveling.
In the example provided in question 23, which type of solution is the egg placed in?
Select the best answer.
Explanation:
When an egg is placed in a hypertonic solution, there is a higher concentration of solutes outside the egg compared to inside. This concentration gradient causes water to move out of the egg through osmosis, leading to the egg shrinking or shriveling due to the loss of water. Therefore, the correct answer is 'Hypertonic.'
Which of the following is true of the Krebs cycle?
Select the best answer.
Explanation:
The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that generate energy through the oxidation of acetyl-CoA derived from sugars produced during glycolysis. It is not primarily a reaction involving proteins or protons being passed along gradients to produce ATP. The cycle is distinct from the glycolic acid cycle, which is a separate metabolic pathway. Therefore, the correct answer is B.
Do enzymes catalyze reactions?
Select the best answer.
Explanation:
Enzymes function as biological catalysts, which means they speed up chemical reactions without being consumed in the process. The correct term that describes what enzymes do to reactions is 'catalyze.' Enzymes do not inhibit or stop reactions; instead, they facilitate and accelerate them by lowering the activation energy required for the reaction to occur.
Which of the following statements about enzymes is not true?
Select the best answer.
Explanation:
Enzymes function to catalyze reactions by lowering the activation energy required for the reaction to occur. Therefore, the statement that enzymes raise the activation energy needed is incorrect. Enzymes have an active site where substrates bind and undergo catalysis. Enzymes are typically proteins that act as biological catalysts.
What is a characteristic of epithelial cells?
Select the best answer.
Explanation:
Epithelial cells are polarized, meaning they have distinct apical and basal surfaces with different functions. This polarity is important for their specialized roles in absorption, secretion, and protection. Therefore, the correct answer is A: 'Polarized.' Choices B and C are incorrect as epithelial cells are not neutral and are not necessarily larger than other cells. Choice D is incorrect as epithelial cells do have specific characteristics.
A child is sick. They have a body temperature that exceeds 37Å—C. The body senses this and begins to sweat in order to lower the temperature. What is this an example of?
Select the best answer.
Explanation:
This scenario describes a negative feedback loop. In negative feedback, the body's response works to reverse the initial stimulus, in this case, sweating to lower the elevated body temperature. This mechanism helps maintain homeostasis by regulating the body's temperature back to the normal range.
Why is homeostasis necessary?
Select the best answer.
Explanation:
Homeostasis is essential for maintaining the internal balance and stability of the body. It regulates various factors, such as temperature, pH levels, and glucose levels, to ensure optimal physiological function. Therefore, all the choices (temperature, pH, and glucose levels) are correct as they are all essential components of homeostasis, working together to keep the body's internal environment stable and functioning properly.
A scientist needs 12 mL of a solution. They have a bottle with 0.12 L in it. Do they have enough?
Select the best answer.
Explanation:
To convert 0.12 L to mL, you multiply by 1000 (since 1 L = 1000 mL). Therefore, 0.12 L = 120 mL. Since the scientist needs only 12 mL, the bottle contains more than enough solution, making choice B the correct answer.
Which of the following statements is false?
Select the best answer.
Explanation:
The correct statement is B. Animal cells do not use chloroplasts to gain energy; instead, they rely on mitochondria for energy production through cellular respiration. Lysosomes in animal cells are responsible for breaking down old cells and cellular waste. Plant cells have a cell wall to provide structural support and protection. Therefore, option B is false, as animal cells do not utilize chloroplasts for energy.
Phenotype refers to the....................of an individual.
Select the best answer.
Explanation:
Phenotype refers to the observable characteristics or traits of an individual, such as physical appearance, behavior, and other observable features. While the genotype represents the genetic makeup of an individual, the phenotype is what is actually expressed or seen. Recessive alleles are specific forms of genes that can be present in the genotype but may not always be expressed in the phenotype.
In a population of dogs, fur color is controlled by two alleles: black (B) and tan (b). The black allele shows complete dominance. If a dog has a tan fur phenotype, what is its genotype?
Select the best answer.
Explanation:
If a dog displays a tan fur phenotype, it indicates that the dog possesses two tan alleles, represented by the genotype bb. In this case, the dog cannot have any black alleles (B) since the black allele demonstrates complete dominance over the tan allele. Therefore, the correct genotype for a dog with a tan fur phenotype is bb.
Using the information provided in question #44, what would be the phenotype if the offspring is Bb?
Select the best answer.
Explanation:
In genetics, when discussing the phenotype of an offspring with a genotype of Bb, the dominant trait 'Black' would be expressed. In this case, the dominant allele 'B' leads to the expression of the black color, overriding the recessive allele 'b,' which would signify tan. Therefore, the correct answer is A, 'Black.' The dominant allele 'B' in the genotype Bb expresses the black color, as it is dominant over the recessive allele 'b.' Hence, the phenotype of the offspring with the genotype Bb would be 'Black.'
If a hard-boiled egg is placed in a beaker of saltwater, what will happen to the egg?
Select the best answer.
Explanation:
When a hard-boiled egg is placed in a beaker of saltwater, the egg will shrivel because water will move out of the egg due to osmosis. Osmosis is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. In this case, the saltwater has a higher solute concentration than the egg, causing water to move out of the egg, leading to shrinkage or shriveling.
In the scenario presented in question #49, what type of solution is the egg immersed in?
Select the best answer.
Explanation:
When an egg is placed in a hypertonic solution, water moves out of the egg into the surrounding solution due to the higher concentration of solutes outside the egg. This results in the egg shrinking or shriveling up as water leaves it, indicating a hypertonic environment.
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