tonicity refers to the movement of

HESI A2

Biology HESI A2 Practice Test

1. Tonicity refers to the movement of:

A. Water
B. Solute
C. Cells
D. None of the above

Correct answer: A

Rationale: Tonicity refers to the movement of water across a membrane in response to differences in solute concentration. In a hypertonic solution, where there is a higher concentration of solutes outside the cell, water will move out of the cell to try to reach equilibrium. In a hypotonic solution, where there is a lower concentration of solutes outside the cell, water will move into the cell to balance the concentrations. Cells and solutes themselves do not actively move in response to tonicity; it is the movement of water that helps achieve equilibrium. Therefore, the correct answer is water (Choice A). Choices B, C, and D are incorrect as tonicity specifically refers to water movement and not the movement of solutes, cells, or none of the above.

2. How many ounces are in 1.5 quarts?

A. 32 ounces
B. 16 ounces
C. 48 ounces
D. 64 ounces

Correct answer: C

Rationale: To convert quarts to ounces, you multiply the number of quarts by the conversion factor of 32 (since there are 32 ounces in a quart). Therefore, 1.5 quarts is equal to 1.5 x 32 = 48 ounces. The correct answer is 48 ounces. Choice A (32 ounces) is incorrect as it represents the amount of ounces in 1 quart, not 1.5 quarts. Choice B (16 ounces) is incorrect as it is half the amount of ounces in 1 quart. Choice D (64 ounces) is incorrect as it represents the amount of ounces in 2 quarts, not 1.5 quarts.

3. Casey spent $80 on items where each item costs $4. How many items did Casey buy?

A. 12
B. 18
C. 20
D. 24

Correct answer: C

Rationale: To determine the number of items Casey bought for $80, we divide the total amount spent ($80) by the cost per item ($4). The calculation gives us 20, indicating that Casey bought 20 items in total to reach the $80 expenditure ($80 ÷ $4 = 20). Therefore, the correct answer is C, 20. Choices A (12), B (18), and D (24) are incorrect because they do not align with the correct division calculation based on the information provided.

4. How should a researcher test the hypothesis that practicing yoga reduces blood pressure?

A. Record the blood pressure of one male and one female participant before and after participating in a yoga class.
B. Divide 30 female participants into two groups with similar average blood pressure; test each participant’s blood pressure after participating in a yoga class.
C. Divide 30 female participants into two groups with similar average blood pressure; have one group watch television for an hour while the other takes a yoga class, record each participant’s blood pressure after the hour. Repeat daily for two weeks.
D. Start with 15 men and 15 women; have the men watch television for an hour while the women take a yoga class, record each participant’s blood pressure after the hour. Reverse, having the men take a yoga class while the women watch television.

Correct answer: B

Rationale: Option B is the most appropriate way to test the hypothesis that practicing yoga reduces blood pressure. By dividing 30 female participants into two groups with similar average blood pressure levels and testing each participant's blood pressure after participating in a yoga class, the researcher can effectively evaluate the impact of yoga on blood pressure. This design allows for a comparison between the two groups, helping to isolate the effects of yoga practice on blood pressure. Option A only involves one male and one female participant, which may not provide a representative sample. Option C introduces an additional variable of watching television, which could confound the results. Option D lacks consistency in the experimental design by switching the activities between men and women, making it difficult to attribute any observed changes solely to yoga practice.

5. What is the primary function of enzymes?

A. To provide energy for reactions
B. To speed up reactions
C. To decrease activation energy
D. To act as a catalyst

Correct answer: B

Rationale: Enzymes function to speed up reactions by lowering the activation energy required for the reaction to occur. They act as biological catalysts, providing an alternative pathway for the reaction to proceed more rapidly without being consumed in the process. Choices A, C, and D are incorrect because enzymes do not provide energy for reactions (they do not generate energy), their primary function is not to decrease activation energy (though they do lower it), and while they act as catalysts, the primary function is to speed up reactions by lowering activation energy.