Which type of epithelium lines the inner surface of the oral cavity, providing a barrier against external insults?
- A. Simple squamous epithelium
- B. Stratified squamous epithelium
- C. Simple columnar epithelium
- D. Pseudostratified columnar epithelium
Correct Answer: B
Rationale: The oral cavity is constantly exposed to mechanical stress and potential injury from food particles and other external factors. To protect against these insults, a strong and resilient epithelium is needed. Stratified squamous epithelium is the best choice for lining the oral cavity due to its multiple layers of cells. This type of epithelium provides a robust barrier that can withstand abrasion and protect the underlying tissues. Simple squamous epithelium (choice A) is too thin and not suitable for a protective function. Simple columnar epithelium (choice C) is more suited for absorption and secretion functions, not protection against mechanical stress. Pseudostratified columnar epithelium (choice D) is found in respiratory passages and functions in mucociliary clearance, not in providing a protective barrier against external insults in the oral cavity.
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Electrons occupy specific energy levels around the nucleus, but not in fixed orbits. This concept is captured by the:
- A. Bohr model
- B. Quantum mechanical model
- C. Lewis structure
- D. Octet rule
Correct Answer: B
Rationale: The correct answer is the Quantum mechanical model. Unlike the Bohr model with its defined electron paths, the quantum mechanical model uses probability distributions to describe electron locations within energy levels. Choice A, the Bohr model, describes fixed electron orbits, which is not in line with the concept of electron distribution in energy levels. Choices C and D, Lewis structure and Octet rule respectively, are not related to the description of electron distribution around the nucleus in energy levels, making them incorrect answers.
What is the scientific term for the monthly cycle in females that prepares the body for potential pregnancy?
- A. Ovulation cycle
- B. Menstrual cycle
- C. Implantation cycle
- D. Gestation cycle
Correct Answer: B
Rationale: The correct answer is B: Menstrual cycle. The menstrual cycle is the scientific term for the monthly cycle in females that prepares the body for potential pregnancy. This cycle involves various phases, including the release of an egg from the ovary (ovulation), thickening of the uterine lining in preparation for a fertilized egg, and shedding of the uterine lining if pregnancy does not occur (menstruation). Choices A, C, and D are incorrect. Option A, Ovulation cycle, only refers to the specific phase of egg release from the ovary. Option C, Implantation cycle, pertains to the process of the fertilized egg attaching to the uterine wall. Option D, Gestation cycle, denotes the period of fetal development during pregnancy, which is distinct from the monthly cycle preparing the body for potential pregnancy.
Which statement is TRUE about valence electrons?
- A. They are located in the innermost electron shell.
- B. They have the highest binding energy to the nucleus.
- C. They are most likely to participate in chemical bonding.
- D. They have no influence on the element's chemical properties.
Correct Answer: C
Rationale: Valence electrons are the outermost electrons in an atom's electron cloud and are crucial in forming chemical bonds with other atoms. These electrons determine the reactivity and chemical properties of an element, making option C the correct statement. Option A is incorrect as valence electrons are found in the outer shell, not the innermost shell. Option B is incorrect because valence electrons have lower binding energy compared to inner electrons. Option D is incorrect since valence electrons play a significant role in an element's chemical behavior.
In the context of optical fibers, chromatic dispersion refers to:
- A. The total internal reflection of light
- B. The spreading of light pulses due to different colors traveling at slightly different speeds
- C. The bending of light at the fiber core-cladding interface
- D. The absorption of light by the fiber material
Correct Answer: B
Rationale: Chromatic dispersion in optical fibers refers to the spreading of light pulses due to different colors (wavelengths) traveling at slightly different speeds. This phenomenon can cause the different components of a light pulse to arrive at the receiver at slightly different times, leading to signal distortion. Choice A is incorrect because total internal reflection refers to the phenomenon where light is reflected back into the medium it originated from when hitting the boundary at an angle greater than the critical angle. Choice C is incorrect as it describes the principle of light being guided within an optical fiber through total internal reflection at the core-cladding interface. Choice D is incorrect as the absorption of light by the fiber material does not relate to chromatic dispersion.
Which of the following is NOT a common symptom of lactose intolerance?
- A. Gas
- B. Bloating
- C. Diarrhea
- D. Nausea
Correct Answer: D
Rationale: A) Gas: Gas is a common symptom of lactose intolerance. When lactose is not properly digested, it can ferment in the colon, leading to the production of gas.
B) Bloating: Bloating is another common symptom of lactose intolerance. The buildup of gas in the digestive system can cause bloating and discomfort.
C) Diarrhea: Diarrhea is a common symptom of lactose intolerance. When lactose is not broken down in the small intestine, it can draw excess water into the colon, resulting in diarrhea.
D) Nausea: Nausea is not a common symptom of lactose intolerance. While some individuals may experience mild stomach discomfort or cramps, nausea is not typically associated with lactose intolerance.