Nokea
What is the process by which RNA molecules are modified after transcription but before translation?
- A. Replication
- B. Splicing
- C. Editing
- D. Packaging
Correct Answer: B
Rationale: B) Splicing is the correct answer. Splicing is the process by which non-coding regions (introns) are removed from pre-mRNA, and the remaining coding regions (exons) are joined together to form mature mRNA. This modification occurs after transcription but before translation. A) Replication is incorrect as replication is the process by which DNA is copied to produce a new DNA molecule, not RNA modifications. C) Editing may involve RNA editing, but it is not commonly used to describe the modification of RNA molecules after transcription. D) Packaging is not the correct term as it refers to the condensation and organization of DNA into chromatin in eukaryotic cells, not the modification of RNA molecules.
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Which of the following factors would increase the solubility of a gas in a liquid?
- A. Decreasing temperature
- B. Increasing pressure
- C. Decreasing surface area
- D. Increasing particle size
Correct Answer: B
Rationale: The correct answer is increasing pressure. According to Henry's Law, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. Therefore, increasing pressure would force more gas molecules into the liquid, leading to an increase in solubility. Conversely, decreasing temperature, decreasing surface area, and increasing particle size would not directly impact the solubility of a gas in a liquid. Decreasing temperature typically decreases solubility as gases are less soluble at lower temperatures. Decreasing surface area and increasing particle size are related to surface area and not the pressure above the liquid, thus not affecting solubility as pressure does.
During inhalation, which muscle contracts to increase the volume of the thoracic cavity, allowing air to flow into the lungs?
- A. Diaphragm
- B. Intercostal muscles
- C. Abdominal muscles
- D. Pectoral muscles
Correct Answer: A
Rationale: The diaphragm is the primary muscle responsible for inhalation. When it contracts, it moves downward, increasing the volume of the thoracic cavity and creating a pressure gradient that allows air to flow into the lungs. While the intercostal muscles also play a role in expanding the chest cavity during inhalation, the diaphragm is the main muscle involved in this process. Abdominal muscles and pectoral muscles are not directly involved in the process of inhalation.
Where does fertilization of the egg by sperm typically occur?
- A. Ovary
- B. Fallopian tube
- C. Uterus
- D. Vagina
Correct Answer: B
Rationale: Fertilization of the egg by sperm typically occurs in the fallopian tube. After ovulation, the egg is released from the ovary and travels through the fallopian tube, where it may encounter sperm for fertilization. The fallopian tube provides the ideal environment, including necessary nutrients and conditions, for fertilization to take place before the fertilized egg moves towards the uterus for implantation. Choices A, C, and D are incorrect because fertilization does not occur in the ovary, uterus, or vagina. The ovary releases the egg, the uterus is the site for implantation, and the vagina is part of the birth canal but not the typical site for fertilization.
What is the valve that prevents blood from flowing back from the left ventricle into the left atrium?
- A. Tricuspid valve
- B. Mitral valve
- C. Aortic valve
- D. Pulmonic valve
Correct Answer: B
Rationale: The correct answer is the Mitral valve. The mitral valve is located between the left atrium and the left ventricle of the heart. Its function is to prevent the backflow of blood from the left ventricle into the left atrium during ventricular contraction. Choice A, the Tricuspid valve, is incorrect as it is located between the right atrium and right ventricle. Choice C, the Aortic valve, and Choice D, the Pulmonic valve, are also incorrect as they are involved in the circulation of blood leaving the heart rather than preventing backflow within the atria and ventricles.
What is the term for the process of a gas changing directly into a solid?
- A. Condensation
- B. Deposition
- C. Sublimation
- D. Evaporation
Correct Answer: B
Rationale: The correct term for the process of a gas changing directly into a solid is deposition. During deposition, gas particles lose energy and transition directly into the solid state without passing through the liquid phase. Sublimation, on the other hand, is the process in which a solid changes directly into a gas without going through the liquid phase. Condensation is the process where gas changes into a liquid state. Evaporation, on the contrary, is the conversion of a liquid to a gas. Therefore, the correct answer is B, deposition.