protein synthesis begins with a process known as transcription where does this process occur

HESI RN

Biology Practice Test

1. Protein synthesis begins with a process known as transcription. Where does this process occur?

A. In the cytoplasm
B. In the nuclear envelope
C. In the ribosome unit
D. In the nucleus

Correct answer: D

Rationale: The correct answer is D: In the nucleus. Transcription, the initial step of protein synthesis, takes place in the nucleus where DNA is transcribed into mRNA. This mRNA then leaves the nucleus and enters the cytoplasm where translation occurs on the ribosomes. Choices A, B, and C are incorrect because transcription specifically occurs in the nucleus, not in the cytoplasm, nuclear envelope, or ribosome unit.

2. At the beginning of meiosis, how many chromosomes does the diploid parent cell have?

A. 23
B. 24
C. 46
D. 54

Correct answer: C

Rationale: The correct answer is C: 46. At the start of meiosis, the diploid parent cell contains 46 chromosomes. During meiosis, the number of chromosomes is halved, resulting in each gamete having 23 chromosomes. Choice A (23) is incorrect because that is the number of chromosomes in a human gamete, not the parent cell. Choice B (24) and Choice D (54) are also incorrect as they do not reflect the correct number of chromosomes in a diploid parent cell at the beginning of meiosis.

3. In which step of cellular respiration is the most adenosine triphosphate (ATP) created?

A. Electron transport chain
B. Glycolysis
C. Citric acid cycle (the Krebs cycle)
D. All of these produce equal amounts of ATP

Correct answer: A

Rationale: The electron transport chain is the step in cellular respiration that generates the most ATP. During this step, up to 34 ATP molecules can be produced from a single glucose molecule. Choice B, Glycolysis, produces a smaller amount of ATP (2 ATP molecules per glucose), and choice C, Citric acid cycle, produces some ATP but not as much as the electron transport chain. Choice D is incorrect because different steps of cellular respiration produce varying amounts of ATP, with the electron transport chain being the most efficient in ATP generation.

4. Which of the following organelles is the site of cellular respiration?

A. Nucleus
B. Mitochondria
C. Lysosomes
D. Ribosomes

Correct answer: B

Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouse of the cell because they generate most of the cell's supply of ATP through cellular respiration. The other organelles listed, such as the nucleus (choice A), lysosomes (choice C), and ribosomes (choice D), do not play a direct role in cellular respiration. The nucleus contains genetic material, lysosomes are involved in digestion and waste removal, and ribosomes are responsible for protein synthesis.

5. What are the nitrogenous bases of DNA?

A. Adenine, cytosine, guanine, and thymine
B. Adenine, guanine, and uracil
C. Adenine, guanine, and thymine
D. Adenine, cytosine, guanine, and uracil

Correct answer: A

Rationale: The correct answer is A: Adenine, cytosine, guanine, and thymine. These are the four nitrogenous bases found in DNA. Adenine pairs with thymine, and cytosine pairs with guanine, forming the complementary base pairs in the double helix structure of DNA. Choice B is incorrect because uracil is a nitrogenous base found in RNA, not DNA. Choice C is incorrect as it is missing cytosine, one of the four bases in DNA. Choice D is incorrect because uracil is not a nitrogenous base in DNA, and it also lacks thymine, which is essential for DNA structure.