Nursing Elites

1. Which of the following produces the first heart sound ('lub')?

• A. The closing of the aortic and pulmonary valves
• B. The closing of the tricuspid and mitral valves
• C. The opening of the aortic and pulmonary valves
• D. The opening of the tricuspid and mitral valves

Correct answer: B

Rationale: The correct answer is B. The first heart sound, known as the 'lub' sound, is produced by the closure of the tricuspid and mitral valves, which are the atrioventricular valves. This sound marks the beginning of systole in the cardiac cycle. Choice A, the closing of the aortic and pulmonary valves, is incorrect as these valves produce the second heart sound ('dub'). Choice C, the opening of the aortic and pulmonary valves, is incorrect because the first heart sound occurs during ventricular contraction (systole). Choice D, the opening of the tricuspid and mitral valves, is incorrect as the 'lub' sound is associated with the closure, not the opening, of these valves.

2. Consider the graph representing a botanist's data on root growth. What is the independent variable?

• A. Temperature
• B. Root tissue
• C. Light exposure
• D. Root length

Correct answer: C

Rationale: The independent variable is the factor that is intentionally changed or manipulated by the researcher. In this case, light exposure is the independent variable because it is being controlled and tested to observe its effect on root growth. Choices A, B, and D are not the independent variable in this scenario. Temperature, root tissue, and root length are likely dependent variables that could be influenced by the changes in light exposure.

3. How many chromosomes must a normal human sperm cell contain?

• A. An X chromosome.
• B. A Y chromosome.
• C. 23 chromosomes.
• D. Both an X and Y chromosome.

Correct answer: C

Rationale: A normal human sperm cell contains a total of 23 chromosomes, half the number found in a typical human cell which has 46 chromosomes. This includes 22 autosomes and one sex chromosome, which can be either an X or a Y chromosome. Therefore, the correct answer is that a normal human sperm cell must contain 23 chromosomes. Choices A and B are incorrect because a single sex chromosome alone does not represent the total number of chromosomes in a sperm cell. Choice D is incorrect because a sperm cell carries only one sex chromosome, either X or Y, not both.

4. What are the components of the female external genitalia and their functions?

• A. Ovaries: internal reproductive organs
• B. Vulva: external structures of the female genitalia
• C. Uterus: internal reproductive organ for fetal development
• D. Vagina: birth canal

Correct answer: B

Rationale: The corrected answer is B: 'Vulva: external structures of the female genitalia.' The vulva includes external structures such as the labia, clitoris, and vaginal opening. These structures play roles in sexual arousal and protection of the internal genital organs. Choices A, C, and D are incorrect because they are internal reproductive organs. The ovaries produce eggs, the uterus houses the developing fetus, and the vagina serves as the birth canal. Hence, they are not components of the female external genitalia.

5. Why is an extensive network of blood vessels necessary to supply the endocrine glands?

• A. To filter waste from the blood
• B. Because the glands empty directly into the blood
• C. To allow blood to empty into the endocrine system
• D. To filter waste from the endocrine glands

Correct answer: B

Rationale: The correct answer is B. Endocrine glands release hormones directly into the blood, which is why they require a rich blood supply to ensure effective hormone distribution throughout the body. The extensive network of blood vessels allows hormones to be quickly transported to target tissues and organs, regulating various physiological functions. Choices A, C, and D are incorrect because endocrine glands do not filter waste from the blood or the glands themselves. They release hormones into the bloodstream to regulate bodily functions, making a direct connection to the blood supply crucial for their function.

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