Nokea
What is the main difference between a nuclear reactor and a nuclear bomb?
- A. Reactors use enriched uranium, while bombs use natural uranium.
- B. Reactors have controlled chain reactions, while bombs have uncontrolled chain reactions.
- C. Reactors generate electricity, while bombs cause explosions.
- D. Reactors use moderators, while bombs don't.
Correct Answer: B
Rationale: The main difference between a nuclear reactor and a nuclear bomb is that reactors have controlled chain reactions, while bombs have uncontrolled chain reactions. Nuclear reactors are designed to sustain a controlled nuclear reaction to generate electricity. In contrast, nuclear bombs are designed to release a massive amount of energy in an uncontrolled chain reaction, resulting in an explosion. Choice A is incorrect because both reactors and bombs can use enriched uranium. Choice C is incorrect as nuclear reactors also generate electricity, not just bombs. Choice D is incorrect because both reactors and bombs may or may not use moderators, but the key distinction lies in the control of the chain reaction.
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Which of the following is NOT a common symptom of pregnancy?
- A. Fatigue
- B. Nausea
- C. Increased urination
- D. Loss of appetite
Correct Answer: D
Rationale: The correct answer is D, 'Loss of appetite.' Loss of appetite is not a common symptom of pregnancy. In fact, many pregnant individuals experience an increase in appetite due to hormonal changes and increased energy needs during pregnancy. Fatigue, nausea, and increased urination are more commonly reported symptoms during pregnancy. Fatigue is often experienced due to hormonal changes and the body's increased metabolic demands during pregnancy. Nausea, commonly known as morning sickness, is a well-known symptom experienced by many pregnant individuals. Increased urination is a common symptom in pregnancy due to hormonal changes leading to increased blood flow to the kidneys and increased fluid processing by the body.
A guitar string vibrates at a fundamental frequency of 440 Hz. What is the frequency of the second harmonic (first overtone)?
- A. 220 Hz
- B. 440 Hz
- C. 880 Hz
- D. 1760 Hz
Correct Answer: C
Rationale: The second harmonic (first overtone) is twice the frequency of the fundamental frequency. Therefore, the frequency of the second harmonic is 440 Hz * 2 = 880 Hz. The second harmonic has a frequency that is one octave higher than the fundamental frequency, representing the first overtone of the vibrating string. Choice A (220 Hz) is incorrect as it represents half the fundamental frequency and is the second harmonic, not the first overtone. Choice B (440 Hz) is the fundamental frequency itself. Choice D (1760 Hz) is the frequency of the fourth harmonic, not the second harmonic.
Edema, characterized by swelling due to fluid buildup, can be a sign of:
- A. Heart failure
- B. Liver disease
- C. Lymphatic system dysfunction
- D. All of the above
Correct Answer: D
Rationale: Edema is the swelling caused by fluid retention in the body tissues. It can indicate various underlying conditions. Heart failure can lead to fluid buildup due to the heart's ineffective pumping. Liver disease can cause edema by reducing protein production, leading to fluid leakage into tissues. Dysfunction of the lymphatic system can impair fluid drainage, contributing to edema. Therefore, all of the above conditions can manifest with edema, making the correct answer 'All of the above.' Choices A, B, and C are all valid causes of edema, making them incorrect when considered individually. Selecting 'All of the above' encompasses all the possible causes of edema.
What is the role of RNA in the regulation of gene expression?
- A. Provides energy for the process
- B. Controls the timing and location of protein synthesis
- C. Translates the genetic code into amino acids
- D. Stores genetic information
Correct Answer: B
Rationale: A) RNA does not provide energy for the process of gene expression. Energy is typically provided by molecules like ATP. B) RNA plays a crucial role in controlling the timing and location of protein synthesis through processes like transcriptional regulation, RNA splicing, and post-transcriptional modifications. It helps determine when and where specific proteins are produced in the cell. C) While mRNA translates the genetic code into amino acids during the process of translation, this is not the primary role of RNA in the regulation of gene expression. D) RNA does not store genetic information in the same way that DNA does. DNA is the molecule responsible for storing genetic information in the form of genes. Therefore, option B is the most appropriate choice as it accurately describes the role of RNA in regulating gene expression.
The hypothalamus, a part of the brain, plays a crucial role in endocrine regulation. It secretes GnRH (Gonadotropin-releasing hormone) which stimulates the pituitary gland to produce FSH and LH. What is the MAIN function of FSH and LH?
- A. Regulate blood sugar levels
- B. Control growth and development
- C. Stimulate the fight-or-flight response
- D. Maintain calcium homeostasis
Correct Answer: B
Rationale: FSH (Follicle-stimulating hormone) and LH (Luteinizing hormone) are hormones produced by the pituitary gland in response to GnRH from the hypothalamus. FSH plays a key role in the growth and development of ovarian follicles in females and sperm production in males. LH is essential for the maturation of the ovarian follicle, ovulation, and the formation of the corpus luteum in females, as well as the production of testosterone in males. Therefore, the main function of FSH and LH is to control growth and development in the reproductive system. Choices A, C, and D are incorrect as they do not align with the roles of FSH and LH in reproductive physiology. Regulating blood sugar levels is primarily the function of insulin and glucagon, controlling the fight-or-flight response involves hormones like adrenaline and noradrenaline, and maintaining calcium homeostasis is mainly regulated by parathyroid hormone and calcitonin.