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. What is DNA made of?

A. Proteins
B. Nucleotides
C. Lipids
D. Carbohydrates

Correct answer: B

Rationale: DNA is made up of nucleotides, which are the building blocks of genetic material. Choice A (Proteins) is incorrect because while proteins play a crucial role in the body, they are not the building blocks of DNA. Choice C (Lipids) and Choice D (Carbohydrates) are also incorrect as they are not the primary components of DNA.

3. Which of the following are considered the most important molecules in biology?

A. Carbohydrates, lipids, protein, and nucleic acids
B. Carbohydrates, lipids, protein, and calcium
C. Carbohydrates, lipids, protein, and sulfur
D. Carbohydrates, lipids, protein, and iron

Correct answer: A

Rationale: The correct answer is A: Carbohydrates, lipids, protein, and nucleic acids are considered the most important molecules in biology. Carbohydrates are essential for providing energy, lipids for storing energy and forming cell membranes, proteins for various structural and functional roles, and nucleic acids (DNA and RNA) for storing genetic information. Choices B, C, and D are incorrect because while carbohydrates, lipids, and proteins are crucial biomolecules, calcium, sulfur, and iron are not considered among the most important molecules in biology.

4. Which organelle is involved in the synthesis of proteins?

A. Endoplasmic Reticulum
B. Ribosomes
C. Lysosomes
D. Vacuoles

Correct answer: B

Rationale: Ribosomes are the organelles involved in the synthesis of proteins. They are the cellular machinery responsible for translating mRNA into proteins, making them essential for cell function and structure. The other organelles listed, such as the Endoplasmic Reticulum, Lysosomes, and Vacuoles, have different functions unrelated to protein synthesis. The Endoplasmic Reticulum plays a role in protein processing and transport, Lysosomes are involved in digestion and waste removal, and Vacuoles are responsible for storage and maintaining cell turgor pressure.

5. Which molecule is primarily responsible for storing energy in cells?

A. Glucose
B. ATP
C. Fatty acids
D. Starch

Correct answer: B

Rationale: ATP is the correct answer because it is the molecule responsible for storing and providing energy in cells. Glucose is a source of energy but not primarily for storage. Fatty acids are more involved in energy production through oxidation. Starch is a polysaccharide used for energy storage in plants.