Nursing Elites

1. Which structure in the respiratory system is responsible for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream?

• A. Trachea
• B. Bronchi
• C. Alveoli
• D. Bronchioles

Correct answer: C

Rationale: The alveoli are tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide occurs. Oxygen from the air diffuses into the bloodstream through the alveoli, while carbon dioxide from the bloodstream diffuses into the alveoli to be exhaled. The trachea, bronchi, and bronchioles are essential parts of the airway system responsible for transporting air to and from the lungs but do not directly participate in the gas exchange process. Therefore, option C, the alveoli, is the correct answer for the structure responsible for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream.

2. What is a monohybrid cross, and what is the ratio of dominant to recessive gene manifestation?

• A. A cross involving two traits, 9:3:3:1
• B. A cross involving one trait, 3:1
• C. A cross involving two traits, 1:2:1
• D. A cross involving one trait, 1:1

Correct answer: B

Rationale: A monohybrid cross is a genetic cross involving one trait. The ratio of dominant to recessive gene manifestation in the offspring is typically 3:1 when both parents are heterozygous. This ratio is the genotypic ratio, not just the phenotype ratio, where the dominant allele is present in 3 out of 4 offspring, and the recessive allele is present in 1 out of 4 offspring. Choice A is incorrect because it describes a dihybrid cross ratio. Choice C is incorrect as it represents the genotypic ratio for a monohybrid cross involving incomplete dominance. Choice D is incorrect as it does not reflect the typical ratio for a monohybrid cross.

3. Where does gas exchange occur in the human body?

• A. Alveoli
• B. Bronchi
• C. Larynx
• D. Pharynx

Correct answer: A

Rationale: The correct answer is A: Alveoli. Gas exchange occurs in the alveoli, which are tiny air sacs in the lungs. Oxygen from the air we breathe diffuses into the blood vessels surrounding the alveoli, while carbon dioxide from the blood diffuses into the alveoli to be exhaled. The bronchi, larynx, and pharynx are all part of the respiratory system but are not directly involved in gas exchange. The bronchi are airways that lead to the lungs, the larynx is the voice box, and the pharynx is the throat. These structures are important for breathing and vocalization but do not participate in the exchange of gases between the respiratory system and the circulatory system.

4. An atom has 5 protons, 5 neutrons, and 6 electrons. What is the electric charge of this atom?

• A. Neutral
• B. Positive
• C. Negative
• D. Undetermined

Correct answer: C

Rationale: The correct answer is 'Negative.' An atom becomes negatively charged when it has more electrons than protons. In this case, the atom has 6 electrons and 5 protons, resulting in a net negative charge. Choice A 'Neutral' is incorrect because the atom is not balanced in terms of protons and electrons. Choice B 'Positive' is incorrect because having more electrons than protons results in a negative charge. Choice D 'Undetermined' is incorrect, as the charge can be determined based on the relative number of protons and electrons.

5. What happens during a physical change in matter?

• A. A new substance with different properties is formed
• B. The chemical composition of the substance changes
• C. The original substance can be recovered by physical means
• D. Energy is either released or absorbed

Correct answer: C

Rationale: During a physical change in matter, the original substance undergoes a change in its physical state or appearance without any change in its chemical composition. This means that the original substance can be recovered by physical means, such as melting, freezing, boiling, or condensing. No new substance is formed (option A), the chemical composition remains the same (option B), and energy changes can occur but are not a defining characteristic of a physical change (option D). The ability to recover the original substance by physical means distinguishes physical changes from chemical changes.

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