why is dna important for metabolic activities of the cell

HESI A2

HESI A2 Practice Test Biology

1. Why is DNA important for metabolic activities of the cell?

A. It controls the synthesis of enzymes.
B. It stabilizes the cell wall.
C. It initiates cell division.
D. It prevents diffusion of nutrients.

Correct answer: A

Rationale: 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.

2. Three students measured the mass of a product of combustion. They recorded measurements of 14 g, 16 g, and 17 g. If the known mass of the product is 30 g, how would you describe the students’ measurements?

A. Accurate
B. Precise
C. Both accurate and precise
D. Neither accurate nor precise

Correct answer: B

Rationale: The students' measurements are precise because they are consistently close to each other. However, they are not accurate because all the measurements deviate from the known mass of the product (30 g). Accuracy refers to how close a measurement is to the true or accepted value, while precision refers to the level of agreement among repeated measurements. Since the students' measurements are consistent but do not align with the true value, they can be considered precise but not accurate. Choice A is incorrect because accuracy relates to the proximity of the measurements to the true value, which is not the case here. Choice C is incorrect because although the measurements are precise, they are not accurate. Choice D is incorrect because the measurements are precise as they show good agreement with each other, even though they are not accurate.

3. Which of the following is an example of human error in an experiment?

A. an imperfectly calibrated scale
B. contaminating a sterile sample by breathing on it
C. a draft in the laboratory slightly changing the temperature of a liquid
D. failure to account for wind speed when measuring distance traveled

Correct answer: B

Rationale: 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.

4. The cell membrane consists of a bilayer of phospholipids with proteins, cholesterol, and glycoproteins. What does this bilayer create?

A. Impermeable
B. Permeable
C. Selectively permeable
D. Selectively impermeable

Correct answer: C

Rationale: The correct answer is 'Selectively permeable.' The cell membrane's bilayer structure allows it to be selectively permeable, meaning it can control the passage of substances. This property enables the membrane to regulate the entry and exit of specific molecules, ions, and other substances. Choice A, 'Impermeable,' is incorrect as the cell membrane is not completely impermeable and does allow certain substances to pass through. Choice B, 'Permeable,' is also incorrect as it does not address the selective nature of the membrane. Choice D, 'Selectively impermeable,' is a contradictory term and does not accurately describe the cell membrane's function.

5. What is the term for the breakdown of glycogen into glucose subunits?

A. Hydrolysis
B. Reduction
C. Metabolism
D. Transpiration

Correct answer: A

Rationale: 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.