Nokea
Through which structure does blood exit the glomerulus?
- A. Distal tubule
- B. Proximal tubule
- C. Afferent arteriole
- D. Efferent arteriole
Correct Answer: D
Rationale: The correct answer is D, the efferent arteriole. The efferent arteriole carries blood away from the glomerulus after filtration. Blood enters the glomerulus through the afferent arteriole for filtration. The proximal and distal tubules are involved in tubular reabsorption and secretion of substances after filtration occurs in the glomerulus. The efferent arteriole plays a crucial role in maintaining the proper flow of blood through the nephron and ensures that the filtered substances are carried away for further processing in the renal tubules.
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Which of the following vitamins is water-soluble and involved in collagen synthesis and wound healing?
- A. Vitamin A
- B. Vitamin D
- C. Vitamin C
- D. Vitamin E
Correct Answer: C
Rationale: Vitamin C is a water-soluble vitamin that plays a crucial role in collagen synthesis, which is essential for wound healing. Collagen is a protein that helps in the formation of connective tissues, skin, tendons, and blood vessels. Vitamin C also acts as an antioxidant and helps in the absorption of iron. Vitamins A, D, and E have different functions and are not primarily involved in collagen synthesis or wound healing.
What is the approximate threshold value for mammalian neurons?
- A. -80 mV
- B. -55 mV
- C. 0 mV
- D. +35 mV
Correct Answer: B
Rationale: The approximate threshold value for mammalian neurons is around -55 mV. At this membrane potential, the neuron becomes more excitable and is more likely to generate an action potential. If the membrane potential reaches this level or depolarizes beyond it, it triggers the opening of voltage-gated ion channels, leading to the initiation of an action potential. Values below this threshold are considered subthreshold and do not usually result in action potential generation. Understanding the threshold potential is crucial in assessing the excitability and firing properties of neurons, as it represents the critical point at which the neuron transitions from a resting state to an active state, enabling the transmission of electrical signals.
Which organelle in a eukaryotic cell is responsible for producing ATP?
- A. Mitochondria
- B. Lysosomes
- C. Nucleus
- D. Centrioles
Correct Answer: A
Rationale: The correct answer is A, Mitochondria. Mitochondria are commonly referred to as the powerhouse of the cell because they play a crucial role in generating energy in the form of ATP through cellular respiration. Lysosomes are mainly involved in cellular waste management, the nucleus houses genetic material, and centrioles aid in cell division. Thus, among the organelles listed, the mitochondria is primarily responsible for ATP production in eukaryotic cells.
Which of the following statements is correct regarding the pH scale?
- A. A substance with a pH of 3 is more acidic than a substance with a pH of 4.
- B. A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4.
- C. A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4.
- D. A substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.
Correct Answer: D
Rationale: The correct answer is D. The pH scale measures the acidity or basicity of a substance on a scale of 0 to 14. Each whole pH value below 7 is ten times more acidic than the next higher value. Therefore, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4. The difference in pH values indicates the concentration of hydrogen ions in the substance, with lower pH values representing higher acidity and higher pH values representing higher basicity.
The triple point of a substance is the temperature and pressure at which the substance exists as which of the following?
- A. As a gel with solid and liquid trapped in gas
- B. Simultaneously in sol, gel, and plasma phases
- C. Simultaneously in solid, liquid, and gas phases
- D. As a sol with gas and solid trapped in liquid
Correct Answer: C
Rationale: The triple point is a specific condition where a substance can exist simultaneously in all three phases: solid, liquid, and gas. The other options do not accurately describe this state.