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The adrenal cortex produces a group of steroid hormones called corticosteroids. What is a MAJOR function of corticosteroids?
- A. Regulate insulin sensitivity and blood sugar levels
- B. Control blood pressure and electrolyte balance
- C. Stimulate the immune system and inflammatory response
- D. Promote growth and development during puberty
Correct Answer: B
Rationale: Corticosteroids, produced by the adrenal cortex, primarily function to control blood pressure and electrolyte balance. One of the key corticosteroids, aldosterone, plays a crucial role in regulating sodium and potassium levels in the body. This regulation is essential for maintaining blood pressure and electrolyte balance. Choices A, C, and D are incorrect because corticosteroids do not primarily regulate insulin sensitivity and blood sugar levels, stimulate the immune system and inflammatory response, or promote growth and development during puberty. While corticosteroids can have effects on insulin sensitivity, immune response, and growth, their major role is in maintaining blood pressure and electrolyte balance.
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Where is the heart located within the human body cavities?
- A. Dorsal cavity
- B. Ventral cavity
- C. Thoracic cavity
- D. Abdominal cavity
Correct Answer: C
Rationale: The heart is located within the thoracic cavity, specifically in the mediastinum, which is the central compartment of the thoracic cavity. The thoracic cavity is part of the ventral cavity, which also includes the abdominal cavity. The dorsal cavity refers to the posterior side of the body and does not contain the heart. The heart is situated in the thoracic cavity between the lungs and above the diaphragm, making option C the correct choice. Therefore, the correct answer is the thoracic cavity (option C). The ventral cavity (option B) includes the thoracic and abdominal cavities, but the heart is specifically situated in the thoracic cavity. The dorsal cavity (option A) is located on the posterior side of the body, not where the heart is positioned. The abdominal cavity (option D) is below the thoracic cavity and houses organs such as the stomach, liver, and intestines, but it does not contain the heart.
The immune response can be categorized into two main branches:
- A. Humoral and cellular
- B. Innate and adaptive
- C. Primary and secondary
- D. Active and passive
Correct Answer: A
Rationale: - The immune response can be broadly categorized into two main branches: the humoral immune response and the cellular immune response.
- The humoral immune response involves the production of antibodies by B cells and is primarily responsible for defending against extracellular pathogens such as bacteria and viruses in the bloodstream and tissues.
- The cellular immune response involves the activation of T cells, which can directly kill infected cells or help coordinate the immune response. This branch is crucial for combating intracellular pathogens like viruses and some bacteria.
- Options B, C, and D do not accurately represent the main branches of the immune response and are therefore incorrect.
Which of the following is the main organ responsible for producing bile?
- A. Liver
- B. Gallbladder
- C. Pancreas
- D. Stomach
Correct Answer: A
Rationale: The liver is the main organ responsible for producing bile. Bile, a greenish-yellow fluid, is produced by the liver and stored in the gallbladder. Its primary function is to aid in the digestion and absorption of fats in the small intestine. When needed, the gallbladder releases bile into the small intestine to facilitate fat digestion. The pancreas produces digestive enzymes and insulin, not bile, making choice C incorrect. The stomach's primary role is to digest food through gastric juice secretion, making choice D incorrect. Therefore, the correct answer is the liver, as it is the main organ responsible for bile production.
The muscular diaphragm plays a vital role in respiration. When it contracts, it:
- A. Increases lung volume for inhalation
- B. Decreases lung volume for exhalation
- C. Filters dust and particles from inhaled air
- D. Produces mucus to lubricate the airways
Correct Answer: A
Rationale: The muscular diaphragm plays a crucial role in respiration by contracting and flattening during inhalation. This action increases the volume of the thoracic cavity, which leads to a decrease in pressure within the lungs, allowing air to rush in and fill the expanded space. Choice B is incorrect because the diaphragm contracting increases the lung volume for inhalation, not decreases it for exhalation. Choice C is incorrect as the role of filtering dust and particles is primarily performed by the respiratory system's other structures like the nasal passages and the mucous membranes. Choice D is incorrect as mucus production is mainly carried out by specialized cells in the respiratory system and not by the diaphragm.
What is the importance of RNA splicing?
- A. Removes introns from the mRNA molecule
- B. Adds the poly-A tail to the mRNA molecule
- C. Activates the mRNA molecule for translation
- D. Modifies the structure of the protein
Correct Answer: A
Rationale: RNA splicing is a crucial process in gene expression where non-coding regions called introns are removed from the pre-mRNA molecule, and the remaining coding regions called exons are joined together to form the mature mRNA molecule. This process ensures that only the protein-coding sequences are retained in the mRNA for translation, allowing for the production of functional proteins. Therefore, option A is the correct answer as it accurately describes the importance of RNA splicing in generating mature mRNA molecules for protein synthesis.
B) Adding the poly-A tail to the mRNA molecule is a post-transcriptional modification that occurs after RNA splicing and is not directly related to the process of removing introns.
C) Activating the mRNA molecule for translation is typically achieved through the addition of a 5' cap and the poly-A tail, rather than through RNA splicing.
D) Modifying the structure of the protein is not directly related to the process of RNA splicing, which primarily focuses on mRNA maturation by removing non-coding introns.