Diabetes mellitus is a chronic condition affecting blood sugar control. What is the main type of hormone deficiency associated with type 1 diabetes?
- A. Insulin
- B. Glucagon
- C. Estrogen
- D. Testosterone
Correct Answer: A
Rationale: The correct answer is A: Insulin. Type 1 diabetes is characterized by the body's inability to produce insulin, the hormone responsible for regulating blood sugar levels. Insulin deficiency in type 1 diabetes leads to high blood sugar levels as the body cannot effectively utilize glucose for energy. Glucagon (Choice B) is a hormone that works opposite to insulin, raising blood sugar levels. Estrogen (Choice C) and testosterone (Choice D) are not directly involved in blood sugar control or the pathophysiology of type 1 diabetes.
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Balance the following redox reaction in acidic solution: Iâ» (aq) + Crâ‚‚O₇²â» (aq) -> Iâ‚‚ (aq) + Cr³âº (aq). Identify the oxidizing agent and reducing agent.
- A. Iâ» is oxidized, Crâ‚‚O₇²â» is reduced
- B. Iâ» is reduced, Crâ‚‚O₇²â» is oxidized
- C. Both Iâ» and Crâ‚‚O₇²â» are oxidized
- D. Both Iâ» and Crâ‚‚O₇²â» are reduced
Correct Answer: B
Rationale: In the given redox reaction, Iâ» is gaining electrons to form Iâ‚‚, which means Iâ» is being reduced (undergoing reduction). On the other hand, Crâ‚‚O₇²â» is losing electrons to form Cr³âº, indicating that Crâ‚‚O₇²â» is being oxidized (undergoing oxidation). Therefore, Iâ» is the reducing agent and Crâ‚‚O₇²â» is the oxidizing agent. Choice A is incorrect because Iâ» is being reduced, not oxidized. Choice C is incorrect as both species cannot be oxidized in the same reaction. Choice D is incorrect as both species cannot be reduced in the same reaction.
Which part of the nervous system is responsible for the "fight-or-flight" response?
- A. Somatic nervous system
- B. Parasympathetic nervous system
- C. Sympathetic nervous system
- D. Enteric nervous system
Correct Answer: C
Rationale: The sympathetic nervous system is responsible for the 'fight-or-flight' response, triggering the body's automatic response to a perceived threat or danger. This system initiates physiological changes like increased heart rate, dilated pupils, and the release of adrenaline, preparing the body to confront or escape the threat. The somatic nervous system (Choice A) controls voluntary movements, the parasympathetic nervous system (Choice B) is responsible for the 'rest and digest' response to promote relaxation and digestion, and the enteric nervous system (Choice D) regulates the gastrointestinal system. Therefore, they are not associated with the 'fight-or-flight' response.
Which property of a wave remains constant when the wave enters a different medium?
- A. Frequency
- B. Wavelength
- C. Amplitude
- D. Speed
Correct Answer: A
Rationale: When a wave enters a different medium, its frequency remains constant. Frequency is an intrinsic property of the wave determined by its source, and it does not change when transitioning between different mediums. On the other hand, wavelength, amplitude, and speed of the wave can all be altered when the wave moves from one medium to another. Wavelength is dependent on the speed of the wave and can change when entering a different medium due to differences in propagation speed. Amplitude can also change as it is influenced by factors like energy loss or gain at the boundary of the mediums. Speed, determined by the medium's properties, typically changes when a wave transitions between different mediums due to variations in the medium's density and elasticity.
What are the differences between RNA and DNA?
- A. Both have the same structure and function.
- B. RNA is single-stranded, while DNA is double-stranded.
- C. RNA contains ribose sugar, while DNA contains deoxyribose sugar.
- D. RNA has adenine and guanine, while DNA has thymine and cytosine.
Correct Answer: B
Rationale: A) This statement is incorrect. RNA and DNA have different structures and functions. RNA is involved in protein synthesis and other cellular processes, while DNA stores genetic information. B) This statement is correct. RNA is typically single-stranded, while DNA is double-stranded, forming a double helix structure. C) This statement is correct. RNA contains ribose sugar in its backbone, while DNA contains deoxyribose sugar. D) This statement is incorrect. RNA contains adenine, guanine, cytosine, and uracil, while DNA contains adenine, guanine, cytosine, and thymine. Choice B is the correct answer as it accurately describes one of the key differences between RNA and DNA, emphasizing their structural disparity in terms of single-strandedness for RNA and double-strandedness for DNA. Choices A, C, and D contain inaccuracies regarding the structural and compositional distinctions between RNA and DNA, making them incorrect choices.
Which hormone, produced by the pancreas, is involved in the regulation of blood sugar levels by inhibiting the release of insulin and promoting the release of glucose into the bloodstream?
- A. Insulin
- B. Glucagon
- C. Cortisol
- D. Somatostatin
Correct Answer: D
Rationale: The correct answer is D, Somatostatin. Somatostatin is a hormone produced by the pancreas that plays a crucial role in regulating blood sugar levels by inhibiting the release of insulin and promoting the release of glucose into the bloodstream. It acts as a counterbalance to insulin, preventing excess insulin secretion and ensuring the availability of glucose when needed. Therefore, somatostatin helps maintain blood sugar balance in the body. Choices A, B, and C are incorrect. Insulin is responsible for lowering blood sugar levels, while glucagon and cortisol have roles that differ from the functions described in the question.