HESI A2
HESI A2 Practice Test Biology
1. What is the first step in the conversion of glucose to pyruvate?
- A. Glycolysis
- B. Krebs cycle
- C. Electron transport chain
- D. Aerobic respiration
Correct answer: A
Rationale: The correct answer is Glycolysis. Glycolysis is the initial step in the conversion of glucose to pyruvate. During glycolysis, glucose is broken down into pyruvate through a series of enzymatic reactions. Choice B, the Krebs cycle, occurs after glycolysis in aerobic cellular respiration. Choice C, the Electron transport chain, is the final step in aerobic respiration where the majority of ATP is produced. Choice D, Aerobic respiration, is a broader term that encompasses glycolysis, the Krebs cycle, and the electron transport chain, but it is not the specific first step in the conversion of glucose to pyruvate.
2. What are the three main events of the haploid cell cycle?
- A. DNA replication, mitosis, and cytokinesis
- B. DNA replication, meiosis, and cytokinesis
- C. DNA replication, cytokinesis, and degradation
- D. Mitosis, meiosis, and apoptosis
Correct answer: A
Rationale: In the haploid cell cycle, the three main events are DNA replication, where the cell's genetic material is duplicated; mitosis, which is the division of the nucleus to ensure each daughter cell receives a complete set of chromosomes; and cytokinesis, the division of the cell cytoplasm to separate the two daughter cells. Meiosis is not part of the haploid cell cycle as it occurs in diploid cells to produce haploid gametes. Apoptosis is a process of programmed cell death and is not a routine event in the cell cycle. Therefore, the correct answer is A. Choices B, C, and D are incorrect as meiosis and apoptosis are not part of the haploid cell cycle, and degradation is not a typical event in the cell cycle.
3. What molecule is primarily responsible for providing energy to the cell?
- A. ATP
- B. DNA
- C. ADP
- D. Glycogen
Correct answer: A
Rationale: Correct! ATP (Adenosine Triphosphate) is the main molecule that stores and provides energy for cellular activities. ATP is known as the energy currency of the cell, where energy released from the breakdown of nutrients is stored in the high-energy phosphate bonds of ATP. Choices B, C, and D are incorrect because DNA carries genetic information, ADP is the precursor of ATP, and glycogen is a polysaccharide used for energy storage, not direct energy provision.
4. Why can animal cells use a contractile ring but plant cells cannot?
- A. Plant cells can use both methods to divide
- B. Animal cells divide faster, requiring them to pinch apart
- C. Plant cells are too rigid to use a contractile ring
- D. N/A
Correct answer: C
Rationale: Plant cells have a rigid cell wall surrounding them, which prevents them from using a contractile ring for cell division. The rigid cell wall requires plant cells to form a cell plate during cell division instead of pinching apart like animal cells with a contractile ring. Choice A is incorrect because plant cells cannot use a contractile ring due to their rigid cell wall. Choice B is incorrect as the speed of cell division is not the primary reason for the difference in cell division mechanisms between plant and animal cells. Choice D is not applicable as plant cells indeed have a specific limitation in using a contractile ring for cell division.
5. Which organelle organizes protein synthesis?
- A. mitochondrion
- B. nucleus
- C. ribosome
- D. vacuole
Correct answer: C
Rationale: Ribosomes are the organelles responsible for organizing protein synthesis. They are the protein factories of the cell, where amino acids are linked together to form proteins. Mitochondria are known as the powerhouse of the cell, responsible for energy production. The nucleus contains the cell's genetic material but does not directly organize protein synthesis. Vacuoles are responsible for storage and maintaining the cell's turgidity.
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