Nokea
Which of the following accurately describes saltatory conduction?
- A. It is faster than normal nerve conduction
- B. It occurs from one node of Ranvier to the next
- C. It only occurs in myelinated neurons
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, 'All of the above.' Saltatory conduction is faster than normal nerve conduction, occurs from one node of Ranvier to the next, and is exclusive to myelinated neurons. This form of conduction allows for the rapid transmission of nerve impulses by the action potential jumping between the nodes of Ranvier in myelinated neurons, enhancing the efficiency of signal propagation along the axon. Choice A is correct as saltatory conduction is indeed faster than normal conduction. Choice B is accurate as it describes the mechanism of conduction 'jumping' from one node of Ranvier to the next. Choice C is correct because saltatory conduction occurs specifically in myelinated neurons where the myelin sheath insulates the axon except at the nodes of Ranvier, facilitating faster transmission of nerve impulses.
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What is the main function of the lungs?
- A. To transport oxygen and nutrients throughout the body
- B. To coordinate movement and sensory information
- C. To filter waste products from the blood
- D. To exchange oxygen and carbon dioxide between the body and the environment
Correct Answer: D
Rationale: The main function of the lungs is to exchange oxygen and carbon dioxide between the body and the environment. This process occurs through the alveoli in the lungs where oxygen from inhaled air enters the bloodstream, and carbon dioxide is removed from the bloodstream and exhaled. Option A is incorrect as the transportation of oxygen and nutrients throughout the body is primarily carried out by the circulatory system, not the lungs. Option B is incorrect as coordinating movement and sensory information is a function of the nervous system, not the lungs. Option C is incorrect as filtering waste products from the blood is primarily the role of the kidneys, not the lungs. Therefore, the correct answer is D.
What is the breakdown product of creatine phosphate, an energy source used for short bursts of muscle activity?
- A. Glucose
- B. Lactic acid
- C. Carbon dioxide
- D. Creatine
Correct Answer: B
Rationale: Creatine phosphate is utilized as an immediate energy source for short bursts of muscle activity. When it breaks down, it yields lactic acid as a byproduct. Lactic acid accumulation during intense exercise can lead to muscle fatigue and soreness. Therefore, the correct answer is lactic acid. The other choices are incorrect: Glucose is a different energy source derived from carbohydrates; Carbon dioxide is a waste product of cellular respiration, not specifically from creatine phosphate breakdown; Creatine is the precursor compound to creatine phosphate and is not the breakdown product.
Which white blood cell type is responsible for the initial attack on pathogens?
- A. Red blood cells
- B. Platelets
- C. Phagocytes
- D. Lymphocytes
Correct Answer: C
Rationale: Phagocytes are a type of white blood cell that is crucial in the initial attack on pathogens. These cells have the ability to engulf and digest foreign particles such as bacteria and viruses, thereby preventing infections. Red blood cells primarily function in oxygen transport, platelets are vital for blood clotting, and lymphocytes are involved in the immune response. However, phagocytes are specifically designed to provide the initial defense against pathogens by directly attacking and eliminating them.
What is the recommended daily fiber intake for adults?
- A. 10 grams
- B. 25 grams
- C. 35 grams
- D. 50 grams
Correct Answer: B
Rationale: The recommended daily fiber intake for adults is around 25 grams for women and 38 grams for men. Fiber is essential for maintaining a healthy digestive system, preventing constipation, and reducing the risk of chronic diseases such as heart disease and diabetes. Consuming an adequate amount of fiber can also help with weight management and promote overall well-being. Option B is the correct answer based on the recommended daily intake guidelines for adults. Choices A, C, and D are incorrect because they do not align with the established guidelines for fiber intake in adults. 10 grams (choice A) is too low, 35 grams (choice C) is higher than the general recommendation, and 50 grams (choice D) is significantly above the recommended intake, which may lead to digestive issues in some individuals.
What is the difference between polygenic inheritance and pleiotropy?
- A. Polygenic inheritance involves multiple genes influencing one trait, while pleiotropy involves one gene affecting multiple traits.
- B. Polygenic inheritance is found in simple Mendelian traits, while pleiotropy is found in complex traits.
- C. Polygenic inheritance is always quantitative, while pleiotropy can be qualitative or quantitative.
- D. Both involve multiple genes and multiple traits, but the specific mechanisms differ
Correct Answer: A
Rationale: - Polygenic inheritance refers to the situation where a trait is influenced by multiple genes, each contributing a small effect to the phenotype. These traits often show continuous variation and are not easily categorized into discrete categories.
- Pleiotropy, on the other hand, occurs when a single gene influences multiple, seemingly unrelated traits. This means that a mutation in one gene can lead to multiple phenotypic effects across different traits or characteristics.
- Therefore, the key difference between polygenic inheritance and pleiotropy lies in the number of genes involved in influencing a trait (multiple genes in polygenic inheritance vs. one gene in pleiotropy) and the direction of influence (one trait affected by multiple genes in polygenic inheritance vs. multiple traits affected by one gene in pleiotropy).