Nokea
What is the protective fluid surrounding the brain and spinal cord called?
- A. Blood
- B. Cerebrospinal fluid
- C. Plasma
- D. Myelin
Correct Answer: B
Rationale: Cerebrospinal fluid is the protective fluid that surrounds the brain and spinal cord. It acts as a cushion to protect these vital organs from injury and provides nutrients to the nervous system. Blood, plasma, and myelin are not the fluids specifically surrounding the brain and spinal cord. Blood is found within blood vessels, plasma is the liquid component of blood, and myelin is a fatty substance that forms a protective sheath around nerve fibers.
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Which of the following is an example of a weak acid?
- A. Hydrochloric acid (HCl)
- B. Sulfuric acid (H2SO4)
- C. Acetic acid (CH3COOH)
- D. Nitric acid (HNO3)
Correct Answer: C
Rationale: The correct answer is Acetic acid (CH3COOH) because it is a weak acid that only partially dissociates in water, resulting in a lower concentration of H+ ions compared to strong acids like hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3) which completely dissociate in water. Weak acids do not fully ionize in water, leading to a lower concentration of H+ ions in solution. Hydrochloric acid, sulfuric acid, and nitric acid are strong acids that completely dissociate in water, producing a higher concentration of H+ ions. Therefore, they are not examples of weak acids.
Which of the following substances is typically a good conductor of electricity when dissolved in water?
- A. Sugar
- B. Sodium chloride
- C. Olive oil
- D. Oxygen gas
Correct Answer: B
Rationale: Sodium chloride (table salt) is typically a good conductor of electricity when dissolved in water because it dissociates into ions (sodium cations and chloride anions) that can carry an electric current. Sugar (choice A), olive oil (choice C), and oxygen gas (choice D) do not dissociate into ions in water and therefore are not good conductors of electricity. Sugar does not dissociate into ions in water, so it cannot conduct electricity. Olive oil and oxygen gas are nonpolar substances and do not ionize in water, making them poor conductors of electricity.
Antidiuretic hormone (ADH) plays a crucial role in regulating water balance. When ADH levels are high, what happens to urine production?
- A. Urine production increases significantly
- B. Urine production decreases to conserve water
- C. There is no change in urine production
- D. The kidneys stop producing urine altogether
Correct Answer: B
Rationale: When ADH levels are high, urine production decreases to conserve water. ADH acts on the kidneys to increase water reabsorption, leading to the production of concentrated urine and conservation of water in the body. Choice A is incorrect as high ADH levels lead to increased water reabsorption, reducing urine output. Choice C is incorrect since high ADH levels do influence urine production. Choice D is incorrect as the kidneys do not stop producing urine entirely but rather adjust the reabsorption of water based on ADH levels.
Which muscle type is characterized by a combination of voluntary and involuntary control, is striated, and is responsible for pumping blood throughout the circulatory system?
- A. Skeletal muscle
- B. Smooth muscle
- C. Cardiac muscle
- D. Connective tissue
Correct Answer: C
Rationale: The correct answer is C, Cardiac muscle. Cardiac muscle is characterized by a combination of voluntary and involuntary control, is striated, and is responsible for pumping blood throughout the circulatory system. Skeletal muscle is primarily under voluntary control, smooth muscle is primarily under involuntary control, and connective tissue is not a muscle type, but rather provides support and structure to the body.
How is the density of a substance calculated?
- A. Mass / Volume
- B. Volume / Mass
- C. Mass x Volume
- D. None of the above
Correct Answer: A
Rationale: The density of a substance is calculated by dividing the mass of the substance by its volume. The formula for density is Density = Mass / Volume. This calculation allows us to determine how much mass is present in a given volume of a substance, making option A the correct choice. Choice B (Volume / Mass) is incorrect because density is defined as mass per unit volume, so mass should be the numerator. Choice C (Mass x Volume) is incorrect as this would result in a different unit of measurement and not represent density. Choice D (None of the above) is incorrect as there is a specific formula for calculating density, which is mass divided by volume.