Nokea
Which property of a substance describes its ability to conduct heat or electricity?
- A. Reactivity
- B. Conductivity
- C. Density
- D. Viscosity
Correct Answer: B
Rationale: Conductivity is the correct property that describes a substance's ability to conduct heat or electricity. Reactivity is related to how readily a substance undergoes chemical reactions, not its ability to conduct heat or electricity. Density refers to the mass per unit volume of a substance, which is different from its ability to conduct heat or electricity. Viscosity measures a substance's resistance to flow, not its ability to conduct heat or electricity.
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What functional group is present in ethers?
- A. Hydroxyl
- B. Carbonyl
- C. Ether
- D. Amine
Correct Answer: C
Rationale: The functional group present in ethers is -O-, representing an oxygen atom bonded to two alkyl or aryl groups. Therefore, choice C, 'Ether,' is the correct answer. Choices A, B, and D refer to different functional groups: hydroxyl (-OH), carbonyl (C=O), and amine (NH2), respectively, which are not present in ethers. Ethers are characterized by the oxygen atom bonded to two carbon groups, distinguishing them from the other functional groups mentioned in the choices.
Which structure in the respiratory system serves as a passageway for both air and food, with a flap-like structure that prevents food from entering the trachea during swallowing?
- A. Larynx
- B. Pharynx
- C. Trachea
- D. Bronchi
Correct Answer: B
Rationale: The pharynx is the correct answer. The pharynx is a structure in the respiratory system that serves as a passageway for both air and food. It contains a flap-like structure called the epiglottis, which prevents food from entering the trachea during swallowing by covering the opening to the trachea. The larynx, although important in the respiratory system, is located below the pharynx and contains the vocal cords. The trachea is a tube that carries air to and from the lungs, while the bronchi are the two main branches that lead from the trachea into the lungs.
Which layer of the skin, containing connective tissue, blood vessels, and nerve endings, is located beneath the epidermis?
- A. Epidermis
- B. Dermis
- C. Hypodermis
- D. Stratum corneum
Correct Answer: B
Rationale: The correct answer is the dermis. The dermis is the deeper layer of the skin that contains connective tissue, blood vessels, and nerve endings. It is located beneath the epidermis and provides structural support, nourishment, and sensitivity to the skin. The epidermis is the outermost layer of the skin responsible for protection. The hypodermis, also known as the subcutaneous layer, is the deepest layer that contains fat cells and plays a role in insulation and energy storage. The stratum corneum is the outermost layer of the epidermis composed of dead skin cells that are continually shed and replaced.
What is the name of the master gland that regulates the function of many other endocrine glands?
- A. Thyroid gland
- B. Pituitary gland
- C. Hypothalamus
- D. Adrenal gland
Correct Answer: B
Rationale: The pituitary gland is commonly referred to as the master gland because it controls the functions of numerous other endocrine glands in the body. It secretes various hormones that are essential for regulating processes like growth, metabolism, reproduction, and stress response. The thyroid gland (Choice A) primarily regulates metabolism and does not oversee other endocrine glands. The hypothalamus (Choice C) plays a role in regulating the pituitary gland but is not the master gland. The adrenal gland (Choice D) produces hormones related to stress response but is not considered the master gland that regulates other endocrine glands.
The body's first line of defense against pathogens is the innate immune system. Which of the following is NOT a component of the innate immune system?
- A. Physical barriers like skin and mucous membranes
- B. Phagocytes that engulf and destroy pathogens
- C. Inflammatory response to isolate and contain infection
- D. Production of antibodies specific to a particular pathogen
Correct Answer: D
Rationale: The production of antibodies specific to a particular pathogen is a function of the adaptive immune system, not the innate immune system. The innate immune system provides immediate, non-specific defense mechanisms against pathogens, including physical barriers, phagocytes, and inflammatory responses. Choices A, B, and C are all correct components of the innate immune system. Physical barriers like skin and mucous membranes act as the first line of defense, preventing pathogens from entering the body. Phagocytes are specialized cells that engulf and destroy pathogens, while the inflammatory response helps isolate and contain infections to prevent their spread.