HESI A2
HESI A2 Practice Test Biology
1. During protein synthesis, what process uses an RNA strand to produce a complementary strand of DNA?
- A. Transcription
- B. Translation
- C. Transfer synthesis
- D. Codon synthesis
Correct answer: A
Rationale: The correct answer is 'Transcription.' During transcription, an RNA strand is used to produce a complementary strand of DNA. This process is essential for converting the genetic information stored in DNA into RNA. Choice B, 'Translation,' is incorrect as it involves the synthesis of proteins from mRNA. Choice C, 'Transfer synthesis,' is not a recognized term in molecular biology. Choice D, 'Codon synthesis,' is also incorrect as it does not refer to the process of using an RNA strand to produce a complementary DNA strand.
2. Which type of muscles are involved in peristalsis?
- A. Smooth muscles
- B. Cardiac muscles
- C. Skeletal muscles
- D. Epaxial muscles
Correct answer: A
Rationale: Peristalsis is a coordinated, wave-like muscular contraction that propels food and other materials through the digestive tract. Smooth muscles are responsible for this movement in the gastrointestinal tract, providing the involuntary contractions needed for peristalsis to occur. Skeletal muscles, cardiac muscles, and epaxial muscles are not directly involved in peristalsis. Cardiac muscles are found in the heart and are responsible for its contraction. Skeletal muscles are attached to bones and control voluntary movements. Epaxial muscles are located along the vertebral column and are involved in the movement and stabilization of the spine.
3. A paroxysm is a sudden spasm. Another word for this might be ___________.
- A. convulsion
- B. symptom
- C. efficacy
- D. embolism
Correct answer: A
Rationale: The correct answer is A: "convulsion." A paroxysm is defined as a sudden spasm or convulsion. The word "convulsion" specifically refers to a violent and involuntary contraction or spasm of muscles, which aligns perfectly with the description of a paroxysm. On the other hand, choices B, C, and D are incorrect. "Symptom" (B) refers to a manifestation of a condition rather than a physical spasm. "Efficacy" (C) relates to effectiveness or success, not a sudden spasm. "Embolism" (D) refers to the obstruction of a blood vessel, which is unrelated to the concept of a sudden spasm. Therefore, convulsion is the most suitable synonym for a paroxysm in this context.
4. Which best defines the molarity of an aqueous sugar solution?
- A. Grams of sugar per milliliter of solution
- B. Moles of sugar per milliliter of solution
- C. Grams of sugar per liter of solution
- D. Moles of sugar per liter of solution
Correct answer: D
Rationale: The molarity of a solution is defined as the number of moles of solute per liter of solvent. In the case of an aqueous sugar solution, the molarity would be expressed as moles of sugar per liter of solution. This is because molarity is a measurement of the concentration of a solute in a solution based on the number of moles present in a given volume of the solution. Therefore, the correct answer is D. Choices A, B, and C are incorrect because the molarity is specifically defined in terms of moles of solute per liter of solution, not in grams per milliliter or grams per liter. Molarity is a unit of concentration that relates the amount of solute to the volume of the solution, not the mass of the solute.
5. Which organelle is responsible for energy production in the cell?
- A. Nucleus
- B. Mitochondria
- C. Ribosomes
- D. Endoplasmic reticulum
Correct answer: B
Rationale: Mitochondria are the organelles responsible for energy production in the cell. They generate energy through cellular respiration, producing ATP, which is the primary energy currency of the cell. Known as the powerhouse of the cell, mitochondria play a vital role in meeting the energy demands of various cellular processes. The nucleus is responsible for storing genetic material, not energy production. Ribosomes are involved in protein synthesis, not energy production. The endoplasmic reticulum is involved in protein and lipid synthesis, as well as detoxification, but it is not primarily responsible for energy production.
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