Nursing Elites

1. How are sister chromatids distinguished from homologous chromosomes in meiosis I?

• A. Sister chromatids share the same centromere, while homologous chromosomes have different centromeres.
• B. Sister chromatids have identical DNA sequences, while homologous chromosomes have slightly different sequences due to crossing over.
• C. Sister chromatids repel each other, while homologous chromosomes attract each other during synapsis.
• D. Sister chromatids separate during anaphase I, while homologous chromosomes separate during anaphase II.

Correct answer: B

Rationale: In meiosis I, sister chromatids are exact copies of each other, containing identical DNA sequences. On the other hand, homologous chromosomes are pairs of chromosomes, with one inherited from each parent, and they can have different versions of genes due to genetic recombination during crossing over in prophase I. Choice A is incorrect because homologous chromosomes naturally have different centromeres. Choice C is incorrect as sister chromatids and homologous chromosomes do not exhibit repulsion or attraction during synapsis. Choice D is incorrect as sister chromatids separate during anaphase II, not anaphase I, while homologous chromosomes separate during anaphase I.

2. What is the difference between exhalation (expiration) and inhalation (inspiration)?

• A. Exhalation involves active muscle contraction, while inhalation is passive.
• B. Inhalation brings in oxygen-rich air, while exhalation releases carbon dioxide-rich air.
• C. Exhalation occurs through the nose only, while inhalation can occur through the nose or mouth.
• D. Inhalation warms and humidifies air, while exhalation cools and dries air.

Correct answer: A

Rationale: Exhalation (expiration) involves active muscle contraction, specifically the diaphragm and intercostal muscles, to decrease the volume of the thoracic cavity and push air out of the lungs. In contrast, inhalation (inspiration) is a passive process where the diaphragm and external intercostal muscles contract to increase the thoracic cavity volume, allowing air to flow into the lungs. Choice B is incorrect as exhalation removes carbon dioxide-rich air and inhalation brings in oxygen-rich air. Choice C is incorrect because both exhalation and inhalation can occur through the nose or mouth. Choice D is inaccurate as inhalation humidifies and warms the air, while exhalation cools and dries it.

3. What are Merkel cells, located in the epidermis, specialized for?

• A. Melanin production
• B. Temperature sensation
• C. Touch perception
• D. Immune defense

Correct answer: C

Rationale: Merkel cells are specialized touch receptors located in the epidermis of the skin. Their primary function is to perceive light touch and pressure. They play a crucial role in the sensory perception of touch stimuli. Option A, melanin production, is incorrect because Merkel cells are not involved in producing melanin. Option B, temperature sensation, is incorrect as Merkel cells are not specialized for sensing temperature. Option D, immune defense, is also incorrect as Merkel cells do not have a role in immune defense mechanisms.

4. Which of the following macromolecules will always contain nitrogen?

• A. Fatty acids
• B. Proteins
• C. Lipids
• D. Carbohydrates

Correct answer: B

Rationale: The correct answer is B: Proteins. Proteins are the only macromolecules that always contain nitrogen in their amino acid structure. Nitrogen is a key element found in the amino groups of amino acids, which are the building blocks of proteins. Fatty acids (Choice A), lipids (Choice C), and carbohydrates (Choice D) do not always contain nitrogen in their structure. Fatty acids are composed of long hydrocarbon chains and do not contain nitrogen. Lipids consist mainly of carbon, hydrogen, and oxygen, with some classes of lipids containing phosphorus but not nitrogen. Carbohydrates are made up of carbon, hydrogen, and oxygen, forming structures like sugars and starches, but they do not contain nitrogen.

5. A light ray travels from air (refractive index 1.00) into water (refractive index 1.33). What happens to its speed and direction?

• A. Speed increases, direction bends towards the normal.
• B. Speed increases, direction bends away from the normal.
• C. Speed decreases, direction bends towards the normal.
• D. Speed and direction remain unchanged.

Correct answer: C

Rationale: When a light ray travels from air (lower refractive index) to water (higher refractive index), its speed decreases due to the change in the medium. This is because light travels slower in denser mediums. As the light ray enters the denser medium, water in this case, it bends towards the normal (the line perpendicular to the surface of the water). This phenomenon is known as refraction. Choice A is incorrect as the speed of light decreases when entering a denser medium. Choice B is incorrect as the direction bends towards the normal, not away from it. Choice D is incorrect as the speed and direction of the light ray do change when moving from air to water.

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