rna is made from dna through a process called

HESI A2

Biology HESI A2 Practice Exam

1. RNA is made from DNA through a process called ___________.

A. transcription
B. synthesis
C. translation
D. replication

Correct answer: A

Rationale: RNA is made from DNA through a process called transcription. During transcription, an enzyme called RNA polymerase reads the DNA template and synthesizes a complementary RNA molecule. This process is essential for gene expression and allows the information encoded in DNA to be converted into functional RNA molecules. Choice B, 'synthesis,' is incorrect as it is a general term and does not specifically describe the process of RNA formation from DNA. Choice C, 'translation,' is incorrect as it refers to the process where the mRNA is used to assemble amino acids during protein synthesis, not the conversion of DNA to RNA. Choice D, 'replication,' is incorrect as it is the process of making an identical copy of DNA, not converting DNA into RNA.

2. What is the role of ribosomes in the cell?

A. Break down cellular waste
B. Organize cellular division
C. Synthesize proteins
D. Provide cellular structure

Correct answer: C

Rationale: The correct answer is C: Synthesize proteins. Ribosomes are responsible for protein synthesis by linking amino acids together. Choice A is incorrect because ribosomes do not break down cellular waste. Choice B is incorrect as ribosomes do not organize cellular division. Choice D is incorrect because ribosomes do not provide cellular structure.

3. Which component is not found in the nucleotide of DNA?

A. Simple sugar
B. Nitrogen base
C. Phosphate group
D. Citric acid

Correct answer: D

Rationale: 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.

4. What event occurs during telophase?

A. The nuclear envelope disappears.
B. Organelles double in number.
C. Chromosomes separate.
D. Two nuclei are formed.

Correct answer: D

Rationale: During telophase, the final stage of mitosis, the separated chromosomes reach opposite poles of the cell. At this stage, a new nuclear envelope forms around each set of chromosomes, creating two distinct nuclei. This marks the completion of cell division. Choices A, B, and C are incorrect because the disappearance of the nuclear envelope typically occurs during prophase, organelles do not double in number during telophase, and chromosomes separate during anaphase, not telophase.

5. Which of the following is true of the Krebs cycle?

A. It is a redox reaction involving proteins produced during glycolysis
B. It is a redox reaction involving sugars produced during glycolysis
C. Protons are passed along a gradient to produce ATP
D. It is also known as the glycolic acid cycle

Correct answer: B

Rationale: 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.