Nokea
Which of the following nucleic acids carries the genetic information copied from DNA to the ribosomes?
- A. DNA
- B. mRNA
- C. rRNA
- D. tRNA
Correct Answer: B
Rationale: The correct answer is B: mRNA. Messenger RNA (mRNA) is responsible for carrying the genetic information copied from DNA to the ribosomes for protein synthesis. mRNA serves as a temporary copy of the genetic instructions stored in DNA and acts as a messenger between the nucleus and ribosomes in the cytoplasm where protein synthesis occurs. While rRNA (ribosomal RNA) and tRNA (transfer RNA) play essential roles in the process of translation at the ribosomes, mRNA is the nucleic acid directly involved in carrying the genetic code for protein synthesis. Therefore, choices A, C, and D are incorrect as DNA is the original genetic material, rRNA is a component of the ribosomes, and tRNA carries amino acids during protein synthesis, respectively.
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Which of the following substances has an acidic pH?
- A. Lemon juice
- B. Blood
- C. Urine
- D. Salt water
Correct Answer: A
Rationale: The correct answer is A, Lemon juice, which has an acidic pH typically around 2 due to its citric acid content. Blood, urine, and salt water are not typically acidic in nature. Blood has a slightly basic pH, urine can vary but is usually slightly acidic to neutral, and salt water is neutral to slightly alkaline. Lemon juice is a commonly known acidic substance, often used in cooking and cleaning due to its acidic properties.
Which of the following is the carbohydrate monomer?
- A. Disaccharide
- B. Lactose
- C. Monosaccharide
- D. Thymine
Correct Answer: C
Rationale: The correct answer is C: Monosaccharide. Monosaccharides are the simplest form of carbohydrates, consisting of a single sugar unit. They are considered the carbohydrate monomers from which larger carbohydrates like disaccharides (composed of two sugar units) and polysaccharides (containing multiple sugar units) are built. Choices A and B, Disaccharide and Lactose, are not monomers but rather specific types of carbohydrates made up of multiple sugar units. Choice D, Thymine, is a nitrogenous base present in DNA and RNA, not a carbohydrate monomer.
Which type of capillary is the most common and least permeable?
- A. Fenestrated capillaries
- B. Sinusoidal capillaries
- C. Continuous capillaries
- D. Discontinuous capillaries
Correct Answer: C
Rationale: The correct answer is C, continuous capillaries. Continuous capillaries are the most common and least permeable type of capillary. They are found in most tissues, including muscle and the nervous system. Continuous capillaries have a continuous endothelium without fenestrations or large gaps, which limits the movement of substances across their walls.
Choice A, fenestrated capillaries, have pores (fenestrations) in their endothelial cells, making them more permeable than continuous capillaries.
Choice B, sinusoidal capillaries, have a discontinuous endothelium with large gaps between cells, making them more permeable and allowing larger molecules and cells to pass through compared to continuous capillaries.
Choice D, discontinuous capillaries, are similar to sinusoidal capillaries with a discontinuous endothelium, allowing for enhanced permeability compared to continuous capillaries.
If a patient had a heart attack and tissue in the left ventricle lost blood flow, what would you most expect to happen?
- A. Blood would not flow from the lungs.
- B. Blood would back up in the legs.
- C. Blood would not be pumped to the body.
- D. Blood would not be oxygenated.
Correct Answer: C
Rationale: The correct answer is C: 'Blood would not be pumped to the body.' When tissue in the left ventricle loses blood flow due to a heart attack, the ability of the left ventricle to pump oxygenated blood to the body is compromised. This can lead to serious consequences for the patient's overall health and organ function. Choices A, B, and D are incorrect because a heart attack affecting the left ventricle does not directly impact blood flow from the lungs, cause blood to back up in the legs, or prevent blood from being oxygenated. The primary concern is the compromised ability of the left ventricle to pump blood to the rest of the body, affecting overall circulation and organ perfusion.
Which of the following is NOT a major function of the respiratory system in humans?
- A. It provides a large surface area for gas exchange of oxygen and carbon dioxide.
- B. It helps regulate the blood's pH.
- C. It helps cushion the heart against jarring motions.
- D. It is responsible for vocalization.
Correct Answer: C
Rationale: Option C, 'It helps cushion the heart against jarring motions,' is NOT a major function of the respiratory system in humans. The primary functions of the respiratory system include gas exchange, regulation of blood pH, and vocalization. The respiratory system does not play a role in cushioning the heart; that function is primarily carried out by the pericardium and other protective structures around the heart. Choices A, B, and D are major functions of the respiratory system in humans. Choice A refers to the respiratory system's role in gas exchange, Choice B highlights its involvement in regulating blood pH, and Choice D points out its responsibility for vocalization.