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What is the main function of the kidneys?
- A. To filter waste products from the blood
- B. To produce urine
- C. To regulate blood pressure
- D. To produce hormones that help control blood sugar levels
Correct Answer: A
Rationale: The main function of the kidneys is to filter waste products, excess ions, and water from the bloodstream to form urine, which is then excreted from the body. This process helps maintain the body's internal environment by regulating the balance of electrolytes, fluid volume, and pH levels. While the kidneys do produce urine as a result of filtering the blood, their primary function is to filter waste products rather than solely producing urine. Although the kidneys play a role in regulating blood pressure by controlling blood volume and electrolyte concentration, their main function is waste filtration. While the kidneys do produce hormones like erythropoietin and renin that regulate physiological processes, such as red blood cell production and blood pressure, the main role of the kidneys is waste filtration.
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Osteoporosis is a condition that leads to weakened bones and an increased risk of fractures. Which hormone plays a key role in bone health and is often affected in osteoporosis?
- A. Estrogen
- B. Testosterone
- C. Thyroid hormone
- D. Insulin
Correct Answer: A
Rationale: Estrogen plays a crucial role in maintaining bone health by inhibiting bone resorption and promoting bone formation. In postmenopausal women, estrogen levels decrease, leading to an increased risk of osteoporosis due to accelerated bone loss. This hormonal imbalance contributes to weakened bones and an increased risk of fractures in individuals with osteoporosis. Testosterone and thyroid hormone do play roles in bone health, but estrogen has a more significant impact. Testosterone is more commonly associated with muscle mass and strength, while thyroid hormone regulates metabolism. Insulin is not directly involved in bone health and is not typically affected in osteoporosis.
Which of the following is a common property of bases?
- A. Conductivity in aqueous solutions
- B. Sour taste
- C. Reactivity with metals to produce hydrogen gas
- D. Turns red litmus paper blue
Correct Answer: D
Rationale: Bases are substances that can accept protons or donate hydroxide ions in a chemical reaction. One common property of bases is that they turn red litmus paper blue. This is a classic test to distinguish between acids (which turn blue litmus paper red) and bases. Conductivity in aqueous solutions (Option A) is a property of both acids and bases, but not unique to bases alone. Sour taste (Option B) is a property commonly associated with acids, not bases. Reactivity with metals to produce hydrogen gas (Option C) is a property of acids, particularly strong acids, but not bases.
Antigenic variation, a common strategy used by some viruses, allows them to:
- A. Produce toxins
- B. Evade the immune system
- C. Survive outside a host
- D. Replicate rapidly
Correct Answer: B
Rationale: Antigenic variation is a strategy used by some viruses to evade the host's immune response. By constantly changing their surface antigens, viruses can avoid recognition and destruction by the immune system. This allows the virus to persist in the host and continue replicating, leading to prolonged infection and potential transmission to other hosts. Antigenic variation does not directly involve the production of toxins, survival outside a host, or rapid replication, making options A, C, and D incorrect in this context.
In the K-capture process, a type of electron capture, from which electron shell does the electron get captured?
- A. The outermost s-orbital
- B. An inner p-orbital
- C. An inner d-orbital
- D. Any available electron shell
Correct Answer: B
Rationale: The K-capture process involves the capture of an electron from the innermost electron shell, known as the K-shell. The K-shell comprises s and p orbitals. During the K-capture process, an electron is specifically captured from an inner p-orbital within the K-shell. Choices A, C, and D are incorrect because K-capture involves capturing an electron from the innermost shell (K-shell) which consists of s and p orbitals, not the outermost s-orbital, inner d-orbital, or any available electron shell.
What is the scientific term for the involuntary rhythmic contraction and relaxation of the heart muscle?
- A. Peristalsis
- B. Myogenesis
- C. Myocardial contractility
- D. Systole and diastole
Correct Answer: D
Rationale: The correct answer is D: Systole and diastole. Systole and diastole are the two phases of the cardiac cycle where the heart muscle contracts (systole) and relaxes (diastole) rhythmically to pump blood throughout the body. This rhythmic process ensures proper blood circulation by pumping blood to the lungs and the rest of the body. Peristalsis, on the other hand, refers to the involuntary constriction and relaxation of the muscles in the gastrointestinal tract, aiding in the movement of food and waste. Myogenesis is the process of muscle tissue formation, and myocardial contractility pertains to the heart muscle's ability to contract efficiently.