HESI A2
HESI A2 Math Practice Exam
1. The physician ordered 3,000 units of heparin; 5,000 U/mL is on hand. How many milliliters will you give?
- A. 0.5 ml
- B. 0.6 ml
- C. 0.75 ml
- D. 0.8 ml
Correct answer: B
Rationale: To calculate the volume of heparin needed, use the formula: Volume of Heparin = (Ordered Units / Concentration of Heparin). Substituting the values, Volume = (3,000 units / 5,000 U/mL) = 0.6 ml. Therefore, the correct answer is 0.6 ml. Choice A (0.5 ml) is incorrect as it results from an incorrect calculation. Choices C (0.75 ml) and D (0.8 ml) are also incorrect calculations based on the wrong formula application or mathematical errors.
2. How many chromosomes do sperm and egg produce in meiosis?
- A. 23
- B. 46
- C. 25
- D. 50
Correct answer: A
Rationale: During meiosis, sperm and egg cells produce half the number of chromosomes found in somatic cells. Each contributes 23 chromosomes, which combine to form a zygote with a total of 46 chromosomes. Choice B (46) is incorrect because this is the number of chromosomes produced in mitosis, not meiosis. Choices C (25) and D (50) are also incorrect as they do not align with the chromosome count in sex cells during meiosis.
3. A bicycle and a car are both traveling at a rate of 5 m/s. Which statement is true?
- A. The bicycle has more kinetic energy than the car.
- B. The bicycle has less kinetic energy than the car.
- C. Both vehicles have the same amount of kinetic energy.
- D. Only the car has kinetic energy.
Correct answer: B
Rationale: Kinetic energy is determined by both the mass and the velocity of an object. While both the bicycle and the car are moving at the same velocity (5 m/s), the car has significantly more mass than the bicycle. As a result, the car has more kinetic energy than the bicycle, even though their speeds are identical. Therefore, choice B is correct. Choices A, C, and D are incorrect because they do not consider the influence of mass on kinetic energy. Choice A is incorrect as the car has more kinetic energy due to its greater mass. Choice C is incorrect because the vehicles have different masses. Choice D is incorrect as both the bicycle and the car possess kinetic energy.
4. Huntington’s disease is carried on the dominant allele. In a situation where two heterozygous parents have the disease, what percentage of their offspring are predicted to be disease-free?
- A. 0%
- B. 25%
- C. 50%
- D. 100%
Correct answer: B
Rationale: In this scenario, both parents are heterozygous for Huntington's disease, meaning each carries one dominant allele (representing the disease) and one recessive allele (representing no disease). When they have offspring, there is a 25% chance that each child will inherit two recessive alleles, making them disease-free. The Punnett square for two heterozygous parents (Hh x Hh) yields a 25% probability of offspring being homozygous recessive (hh) and therefore disease-free. Choice A (0%) is incorrect because there is a possibility of disease-free offspring. Choice C (50%) is incorrect as it represents the likelihood of being a carrier. Choice D (100%) is incorrect as all offspring will not be disease-free in this scenario.
5. Why are boats more buoyant in salt water than in fresh water?
- A. Salt decreases the mass of the boats.
- B. Salt increases the volume of the water.
- C. Salt affects the density of the boats.
- D. Salt increases the density of the water.
Correct answer: D
Rationale: Salt increases the density of water, making saltwater more buoyant than freshwater. The higher density of saltwater provides more lift to a boat, enabling it to float more easily compared to in freshwater. Choice A is incorrect because salt does not affect the mass of the boats. Choice B is incorrect as salt does not increase the volume of water. Choice C is incorrect since salt affects the density of water, not the boats themselves. Therefore, the correct answer is that salt increases the density of the water, resulting in boats being more buoyant in salt water than in fresh water.
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