HESI A2
Biology HESI A2 2024
1. During which phase of cell division do the chromosomes replicate?
- A. Prophase
- B. Interphase
- C. Anaphase
- D. Telophase
Correct answer: B
Rationale: Chromosomes replicate during the interphase of the cell cycle. Interphase is the phase where the cell prepares for division by undergoing various activities such as growth, DNA replication, and protein synthesis. During DNA replication in interphase, each chromosome in the cell is duplicated to form two sister chromatids, which are then separated during cell division. Prophase is the phase where the chromosomes condense, and the nuclear envelope breaks down. Anaphase is the phase where sister chromatids are pulled apart towards opposite poles of the cell. Telophase is the phase where the nuclear envelope reforms, and chromosomes begin to decondense.
2. What is the perimeter of a square with a side length of 5 meters?
- A. 15 meters
- B. 20 meters
- C. 25 meters
- D. 30 meters
Correct answer: B
Rationale: The formula to calculate the perimeter of a square is P = 4s, where P is the perimeter and s is the length of a side. Given that the side length is 5 meters, the perimeter is 4 * 5 = 20 meters. Therefore, the correct answer is B. Choices A (15 meters), C (25 meters), and D (30 meters) are incorrect as they do not correctly apply the formula to calculate the perimeter of a square.
3. How does increasing the concentration of reactants affect a chemical reaction?
- A. Decreases the reaction rate
- B. Increases the reaction rate
- C. Stops the reaction
- D. Has no effect
Correct answer: B
Rationale: Increasing the concentration of reactants leads to more reactant particles being available, which, in turn, increases the likelihood of successful collisions between particles. This higher frequency of collisions results in a higher reaction rate. Therefore, option B, 'Increases the reaction rate,' is the correct answer. Choice A, 'Decreases the reaction rate,' is incorrect because higher reactant concentration usually speeds up the reaction. Choice C, 'Stops the reaction,' is incorrect as increasing concentration promotes more collisions, enhancing the reaction. Choice D, 'Has no effect,' is incorrect because changing reactant concentration directly impacts the reaction rate in most cases.
4. Which type of blood cell is primarily responsible for fighting infections?
- A. Red blood cells
- B. White blood cells
- C. Platelets
- D. Plasma
Correct answer: B
Rationale: White blood cells, also known as leukocytes, play a crucial role in the immune system by primarily combating infections. These cells can identify and destroy pathogens, such as bacteria and viruses, helping the body defend against illnesses and maintain overall health. Red blood cells are responsible for oxygen transport, platelets aid in blood clotting, and plasma carries various components throughout the circulatory system, but none of these functions involve fighting infections like white blood cells do.
5. What is the boiling point of water in °C?
- A. 90°C
- B. 100°C
- C. 95°C
- D. 80°C
Correct answer: B
Rationale: The correct answer is 100°C. The boiling point of water in Celsius is 100°C, which is standard at sea level. This is the temperature at which water changes from a liquid to a gas phase under standard atmospheric pressure. Choice A (90°C), Choice C (95°C), and Choice D (80°C) are incorrect because they do not represent the standard boiling point of water at sea level.
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