Nokea
When is work done by a force on an object?
- A. Only when the object moves in the direction of the force
- B. Only when the object moves against the force
- C. Only when the object moves vertically
- D. Only when the force is applied for a specific duration
Correct Answer: A
Rationale: Work is done by a force on an object when the object moves in the direction of the force. This is because work is defined as the product of the force applied to an object and the distance over which the force is applied. When the object moves in the direction of the force, the force contributes to the displacement of the object, resulting in work being done. If the object moves perpendicular to the force, no work is done because the force does not contribute to the displacement. Moving against the force also results in work being done as the force is causing the displacement. The vertical movement of the object does not determine whether work is done; it is the alignment of the force with the object's displacement that matters. The duration of force application does not impact whether work is done; as long as the force causes the object to move in its direction, work is being done.
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Which blood vessels carry oxygenated blood from the heart to the rest of the body?
- A. Pulmonary arteries
- B. Pulmonary veins
- C. Systemic arteries
- D. Systemic veins
Correct Answer: C
Rationale: The correct answer is systemic arteries. Systemic arteries carry oxygenated blood from the heart to the rest of the body to provide oxygen and nutrients to tissues. Pulmonary arteries carry deoxygenated blood from the heart to the lungs for oxygenation. Pulmonary veins transport oxygenated blood from the lungs back to the heart. Systemic veins return deoxygenated blood from the body tissues to the heart for reoxygenation. Therefore, choices A, B, and D are incorrect as they do not carry oxygenated blood away from the heart to the body.
What is the function of ribosomal RNA (rRNA)?
- A. Carries amino acids to the ribosomes
- B. Reads the genetic code on mRNA
- C. Forms the structural framework of ribosomes
- D. Controls the rate of protein synthesis
Correct Answer: C
Rationale: Ribosomal RNA (rRNA) plays a crucial role in forming the structural framework of ribosomes. Ribosomes are the cellular organelles responsible for protein synthesis and consist of both protein and rRNA components. The primary function of rRNA is to provide the structural support necessary for ribosomes to function properly. This structural framework allows the ribosome to interact with messenger RNA (mRNA) and transfer RNA (tRNA) during translation, where genetic information encoded in mRNA is used to assemble proteins from amino acids. Therefore, rRNA's main role is in contributing to the structure and function of ribosomes, rather than directly carrying amino acids, reading the genetic code, or controlling the rate of protein synthesis. Choices A, B, and D are incorrect because rRNA does not carry amino acids to the ribosomes (tRNA does this), read the genetic code (this is the role of ribosomes and tRNA), or control the rate of protein synthesis (this is regulated by various factors but not directly by rRNA).
Which of the following processes breaks down cellular components for recycling or waste removal?
- A. Photosynthesis
- B. Cellular respiration
- C. Cell division
- D. Phagocytosis
Correct Answer: D
Rationale: The correct answer is D: Phagocytosis. Phagocytosis is the process by which cells engulf and break down cellular components or foreign particles for recycling or waste removal. It is a vital mechanism used by cells to maintain homeostasis and remove waste materials. Photosynthesis (A) is the process by which plants convert light energy into chemical energy to produce food, not for breaking down cellular components. Cellular respiration (B) is the process by which cells generate energy from nutrients, not for waste removal. Cell division (C) is the process by which cells replicate and divide to form new cells during growth, repair, or development, not for breaking down cellular components.
What is the microscopic functional unit of the kidney responsible for filtering blood?
- A. Ureter
- B. Nephron
- C. Renal pelvis
- D. Bladder
Correct Answer: B
Rationale: The nephron is the correct answer as it is the microscopic functional unit of the kidney responsible for filtering blood. It is composed of a renal corpuscle (glomerulus and Bowman's capsule) and a renal tubule. The other options, such as (A) Ureter, (C) Renal pelvis, and (D) Bladder, do not play a role in filtering blood within the kidney. The ureter is a tube that carries urine from the kidney to the bladder. The renal pelvis is a part of the kidney where urine collects before entering the ureter. The bladder is an organ that stores urine until it is excreted from the body.
What is the role of surfactant in the respiratory system?
- A. To trap dust particles
- B. To increase lung compliance
- C. To produce mucus
- D. To generate oxygen during respiration
Correct Answer: B
Rationale: The correct answer is B: To increase lung compliance. Surfactant is a substance produced by type II alveolar cells in the lungs that reduces surface tension in the alveoli. This reduction in surface tension helps to increase lung compliance, making it easier for the lungs to expand and contract during breathing. Improved lung compliance is essential for efficient gas exchange in the respiratory system, facilitating oxygen uptake and carbon dioxide removal. Choices A, C, and D are incorrect because surfactant does not trap dust particles, produce mucus, or generate oxygen during respiration. Instead, its primary function lies in reducing surface tension to prevent alveolar collapse and improve lung compliance for optimal gas exchange.