Nokea
What does half-life refer to?
- A. Radioactive intensity to completely disappear
- B. The number of neutrons in a nucleus to double
- C. The number of protons in a nucleus to change
- D. An isotope to decay by half of its initial quantity
Correct Answer: D
Rationale: Half-life refers to the time it takes for half of the radioactive atoms in a sample to decay. This means that after one half-life, half of the initial quantity of the radioactive substance will have decayed. Choice A is incorrect because radioactive intensity doesn't completely disappear during half-life. Choice B is incorrect as half-life doesn't refer to the number of neutrons doubling. Choice C is incorrect as half-life doesn't relate to the number of protons changing.
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How do sweat glands help regulate body temperature?
- A. Producing sebum for lubrication
- B. Constricting blood vessels in the skin
- C. Releasing a watery fluid that evaporates for cooling
- D. Thickening the epidermis for insulation
Correct Answer: C
Rationale: Sweat glands play a vital role in regulating body temperature by releasing a watery fluid that evaporates from the skin's surface. This evaporation process helps cool the body down by dissipating heat, which is essential for maintaining a stable internal temperature. Choice A is incorrect because sweat glands do not produce sebum but rather a watery fluid. Choice B is incorrect because sweating itself does not involve the constriction of blood vessels; instead, it promotes heat loss through evaporation. Choice D is incorrect as sweat glands do not thicken the epidermis for insulation but rather facilitate the cooling process through sweat evaporation.
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.
Which of the following is NOT a type of chemical bond?
- A. Ionic bond
- B. Covalent bond
- C. Metallic bond
- D. Gravitational bond
Correct Answer: D
Rationale: Ionic, covalent, and metallic bonds are all types of chemical bonds that involve the sharing or transfer of electrons between atoms. An ionic bond occurs when one atom donates an electron to another, creating positive and negative ions that attract each other. A covalent bond involves the sharing of electrons between atoms to achieve a stable electron configuration. Metallic bonds are formed between metal atoms where electrons are delocalized and move freely among the metal ions. On the other hand, a gravitational bond is not a type of chemical bond. It refers to the force of attraction between two objects with mass, such as the gravitational force between the Earth and objects on its surface. Therefore, the correct answer is 'Gravitational bond.'
What happens to the frequency of a wave if its wavelength decreases while the speed remains constant?
- A. Frequency decreases
- B. Frequency increases
- C. Frequency remains constant
- D. Frequency becomes zero
Correct Answer: B
Rationale: The correct answer is B: Frequency increases. Frequency and wavelength are inversely proportional in a wave with a constant speed. When the wavelength decreases while the speed remains constant, the frequency must increase to maintain the constant speed of the wave. This relationship is governed by the equation: speed = frequency x wavelength. Choice A is incorrect as frequency increases when wavelength decreases. Choice C is incorrect as the frequency changes in this scenario. Choice D is incorrect as the frequency does not become zero but increases when the wavelength decreases.
Which division of the autonomic nervous system is responsible for the 'rest and digest' response, promoting relaxation and conservation of energy?
- A. Sympathetic nervous system
- B. Parasympathetic nervous system
- C. Somatic nervous system
- D. Central nervous system
Correct Answer: B
Rationale: The correct answer is B: Parasympathetic nervous system. The parasympathetic nervous system is responsible for the 'rest and digest' response, promoting relaxation, conserving energy, and facilitating activities like digestion and lowering heart rate. The sympathetic nervous system, which is not the correct answer, triggers the 'fight or flight' response, preparing the body for stressful situations by increasing heart rate, dilating airways, and releasing adrenaline. The somatic nervous system (choice C) controls voluntary movements, not the autonomic functions related to 'rest and digest.' The central nervous system (choice D) includes the brain and spinal cord and is not specifically involved in the autonomic regulation of bodily functions like the 'rest and digest' response.