Nokea
How do vaccines work?
- A. By directly killing pathogens
- B. By introducing weakened or inactive versions of pathogens to trigger an immune response
- C. By stimulating the immediate production of specific antibodies
- D. None of the above
Correct Answer: B
Rationale: Vaccines work by introducing weakened or inactive versions of pathogens to trigger an immune response in the body. This exposure helps the immune system recognize and remember the pathogen, enabling a faster and more effective response upon future exposure. Vaccines do not directly kill pathogens but prepare the immune system for a potential encounter, enhancing protection. They also do not stimulate the immediate production of specific antibodies as the immune response takes time to develop upon vaccination. Choice A is incorrect because vaccines do not kill pathogens directly; they prime the immune system to recognize and respond to them. Choice C is incorrect because while vaccines lead to the production of specific antibodies, it is not immediate, as it takes time for the immune response to develop and produce these antibodies.
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Which vitamin requires intrinsic factor for proper absorption?
- A. Vitamin A
- B. Vitamin C
- C. Vitamin D
- D. Vitamin B12
Correct Answer: D
Rationale: Vitamin B12 requires intrinsic factor, a glycoprotein secreted by the parietal cells of the stomach, for proper absorption in the small intestine. Intrinsic factor binds to vitamin B12 and facilitates its absorption in the ileum. Deficiency in intrinsic factor can lead to pernicious anemia, a condition characterized by a lack of vitamin B12 absorption. Options A, B, and C are incorrect. Vitamin A is absorbed in the small intestine with the help of bile salts; Vitamin C is absorbed in the small intestine via active transport; Vitamin D is absorbed in the small intestine through a process involving bile salts and micelles. It is essential for students to understand this relationship as it highlights the importance of intrinsic factor in the absorption of specific vitamins and the consequences of its deficiency.
What is the process of converting simple sugars into complex carbohydrates called?
- A. Glycolysis
- B. Gluconeogenesis
- C. Krebs cycle
- D. Oxidative phosphorylation
Correct Answer: B
Rationale: Gluconeogenesis is the correct answer. It is the process of synthesizing glucose from non-carbohydrate sources, such as amino acids or glycerol. A) Glycolysis is the process of breaking down glucose into pyruvate to produce energy. C) The Krebs cycle, also known as the citric acid cycle, generates energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. D) Oxidative phosphorylation is the final stage of cellular respiration where ATP is produced using energy derived from the electron transport chain. Therefore, choices A, C, and D are not the processes involved in converting simple sugars into complex carbohydrates.
What is a temporary loss of consciousness due to insufficient blood flow to the brain called?
- A. Stroke
- B. Seizure
- C. Syncope (fainting)
- D. Coma
Correct Answer: C
Rationale: Syncope, also known as fainting, is a temporary loss of consciousness caused by insufficient blood flow to the brain. It results from a brief interruption in the brain's blood supply, leading to a temporary loss of consciousness. The correct answer is C. A stroke, option A, is caused by a blockage or rupture of blood vessels in the brain, not insufficient blood flow. Seizure, option B, involves a sudden surge of electrical brain activity, not reduced blood flow. Coma, option D, is characterized by prolonged unconsciousness, not a temporary loss of consciousness due to insufficient blood flow.
According to Newton's third law of motion, for every action, there is an equal and opposite _________.
- A. Reaction
- B. Force
- C. Acceleration
- D. Momentum
Correct Answer: A
Rationale: Newton's third law of motion states that for every action, there is an equal and opposite reaction. This law emphasizes that forces always exist in pairs. When one object exerts a force on a second object (action), the second object exerts an equal force in the opposite direction back on the first object (reaction). This principle is crucial in understanding the interactions between objects and the resulting motion observed in the physical world. Choices B, C, and D are incorrect because while force is involved, the specific concept highlighted by Newton's third law is the equal and opposite reaction. Acceleration and momentum are also related to motion but are not directly tied to Newton's third law of motion, which focuses on the equality and oppositeness of forces in interactions.
What happens to the concentration of hydrogen ions (\([H^+]\)) in a solution as the pH increases?
- A. Increases
- B. Decreases
- C. Remains constant
- D. Becomes neutral
Correct Answer: B
Rationale: As the pH increases, the concentration of hydrogen ions decreases. The relationship is inversely proportional