Nokea
During gas exchange in the alveoli, what happens to oxygen?
- A. Oxygen is released from the alveoli into the bloodstream.
- B. Oxygen is absorbed from the alveoli into the bloodstream.
- C. Oxygen is converted into carbon dioxide.
- D. Oxygen is stored in the alveoli for later use.
Correct Answer: B
Rationale: During gas exchange in the alveoli, oxygen is absorbed from the alveoli into the bloodstream. This process occurs due to the difference in partial pressures of oxygen between the alveoli and the bloodstream, causing oxygen to move from an area of higher concentration (alveoli) to an area of lower concentration (bloodstream). Oxygen is then transported by red blood cells to tissues throughout the body for cellular respiration. Choice A is incorrect as oxygen moves from the alveoli into the bloodstream, not the other way around. Choice C is incorrect as oxygen is not converted into carbon dioxide during gas exchange. Choice D is incorrect as oxygen is not stored in the alveoli but rather continuously exchanged with carbon dioxide during respiration.
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What effect does doubling the net force applied to an object have on its acceleration, assuming mass remains constant?
- A. Acceleration doubles
- B. Acceleration is halved
- C. Acceleration remains the same
- D. Acceleration quadruples
Correct Answer: A
Rationale: According to Newton's second law of motion, acceleration is directly proportional to the net force applied to an object when mass is constant. Therefore, if the net force is doubled, the acceleration of the object will also double. This relationship is expressed by the formula F=ma, where F is the net force, m is the mass, and a is the acceleration. When mass is constant, doubling the force applied will result in a proportional doubling of acceleration. Choices B, C, and D are incorrect because doubling the net force does not halve, maintain, or quadruple the acceleration; it directly and proportionally increases the acceleration.
What determines the final velocity of a block sliding down a frictionless inclined plane?
- A. The length of the incline
- B. The angle of the incline
- C. The mass of the block
- D. All of the above
Correct Answer: B
Rationale: The final velocity of a block sliding down a frictionless inclined plane is determined by the angle of the incline. The angle directly impacts the acceleration of the block, affecting the final velocity it attains at the bottom. The length of the incline and the mass of the block do not play a direct role in determining the final velocity. Therefore, the correct answer is the angle of the incline (Choice B). Choices A and C are incorrect because the length of the incline and the mass of the block do not have a direct influence on the final velocity of the block in this scenario.
Which of the following is an example of a polymer?
- A. Methane
- B. Ethanol
- C. Polyethylene
- D. Acetic acid
Correct Answer: C
Rationale: The correct answer is C, Polyethylene. Polyethylene is a polymer composed of a large number of repeating ethylene units linked together, forming a long-chain molecule, characteristic of polymers. Methane, ethanol, and acetic acid are small organic molecules that do not demonstrate the repeating unit structure typical of polymers. Therefore, they are not examples of polymers.
The small intestine is where most of the chemical digestion and nutrient absorption occur. What is the finger-like projection in the small intestine that increases its surface area for absorption?
- A. Rugae
- B. Villi
- C. Microvilli
- D. All of the above
Correct Answer: C
Rationale: Microvilli are the finger-like projections in the small intestine that increase its surface area for absorption. Villi are also present in the small intestine and help increase the surface area for absorption. However, microvilli are smaller structures found on the surface of villi, further increasing the surface area available for nutrient absorption. Rugae are folds in the stomach that allow for expansion when food is consumed and are not found in the small intestine. Therefore, the correct answer is C) Microvilli. Villi and microvilli are specific to the small intestine, playing vital roles in nutrient absorption, while rugae are specific to the stomach's structure and function, serving a different purpose than increasing surface area for absorption.
What is the role of the appendix, a small pouch attached to the large intestine?
- A. To store waste products
- B. To produce immune cells
- C. To secrete digestive enzymes
- D. To regulate blood sugar levels
Correct Answer: B
Rationale: The appendix is a small pouch attached to the large intestine and is part of the lymphatic system. Its main function is to produce immune cells, particularly lymphocytes, which play a crucial role in fighting infections and maintaining gut health. Therefore, the correct answer is B. The appendix does not serve to store waste products (option A), secrete digestive enzymes (option C), or regulate blood sugar levels (option D).