HESI A2
HESI A2 Practice Test Biology
1. Which of the following is necessary for cell diffusion?
- A. water
- B. membrane
- C. ATP
- D. gradient
Correct answer: D
Rationale: The correct answer is 'gradient.' In cell diffusion, substances move from an area of high concentration to an area of low concentration, driven by the concentration gradient. This process does not require water, membrane, or ATP specifically. Water can aid in the movement of substances, but it is not necessary for diffusion itself. The membrane is involved in regulating diffusion but is not a requirement for the process. ATP is not directly involved in simple diffusion processes; instead, it is more related to active transport mechanisms. Therefore, the concentration gradient is essential for cell diffusion to occur.
2. Two organisms live in a relationship from which both benefit. What is this called?
- A. Mutualism
- B. Parasitism
- C. Commensalism
- D. Competition
Correct answer: A
Rationale: Mutualism is a type of symbiotic relationship between two organisms in which both parties benefit from the association. It is a mutually beneficial interaction where both organisms gain something valuable, such as food, protection, or some other resource. This contrasts with parasitism, where one organism benefits at the expense of the other, commensalism, where one organism benefits while the other is unaffected, and competition, where both organisms are negatively affected by their interaction.
3. Athletes are often concerned with the question of what they need in their diets to increase muscle mass and strength. What biologic molecule would you recommend that would accomplish this?
- A. carbohydrates
- B. proteins
- C. lipids
- D. nucleic acids
Correct answer: B
Rationale: Proteins are essential for building and repairing muscle tissue. They contain amino acids, which are the building blocks of muscles. Athletes looking to increase muscle mass and strength should focus on consuming adequate amounts of high-quality proteins in their diets. Carbohydrates provide energy for workouts, lipids are important for overall health but do not directly contribute to muscle building, and nucleic acids are involved in genetic activities rather than muscle growth.
4. Which is not a product of the Krebs cycle?
- A. ATP
- B. Carbon dioxide
- C. Glucose
- D. NADH
Correct answer: C
Rationale: Glucose is not a direct product of the Krebs cycle. Glucose is a starting molecule that undergoes glycolysis outside the mitochondria to produce pyruvate, which then enters the mitochondrial matrix to participate in the Krebs cycle. The Krebs cycle primarily generates ATP, carbon dioxide, and NADH as products. Choices A, B, and D are all products of the Krebs cycle, making them incorrect answers.
5. 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.
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