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Which of the following substances is responsible for donating H+ ions to act as a buffer when blood pH rises?
- A. Carbon Monoxide
- B. Oxygen
- C. Carbon Dioxide
- D. Carbonic Acid
Correct Answer: D
Rationale: Carbonic acid is a pivotal buffer in blood that plays a key role in maintaining pH balance. When blood pH rises, indicating increased alkalinity, carbonic acid releases hydrogen ions (H+) to counterbalance the excess base, thereby preventing significant changes in pH levels. This mechanism highlights the essential function of carbonic acid in regulating the acid-base equilibrium in the blood.
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A group of students performed an experiment to test terminal velocity, which is the greatest speed obtained by a falling object. The students dropped different numbers of coffee filters and measured the resulting terminal velocity. Data Table: Mass (g): 1.01, 1.99, 3.02, 4.0, 5.01; Terminal Velocity (m/s): 1.74, 2.48, 3.04, 3.50, 3.80. Which of the following conclusions is supported by the data?
- A. Terminal velocity is reached when the force of gravity equals air resistance.
- B. The greater the number of filters, the smaller the terminal velocity.
- C. Heavier objects reach terminal velocity more quickly.
- D. Heavier objects fall faster than lighter objects.
Correct Answer: B
Rationale: The data indicates that as the number of coffee filters increases, the terminal velocity decreases, supporting the conclusion in Choice B. Terminal velocity is reached when the force of gravity equals air resistance, which is not explicitly shown in the data. Heavier objects reaching terminal velocity more quickly and heavier objects falling faster than lighter objects are not supported by the provided data, as the experiment was conducted with coffee filters of different masses, not different objects.
Among the following molecules, which one contains the fewest covalent bonds?
- A. Water molecule (H2O)
- B. Methane molecule (CH4)
- C. Chlorine molecule (Cl2)
- D. Ammonia molecule (NH3)
Correct Answer: C
Rationale: The correct answer is C. The chlorine molecule (Cl2) contains the fewest covalent bonds as it consists of two chlorine atoms sharing a single covalent bond. Water (H2O), methane (CH4), and ammonia (NH3) involve multiple atoms bonded together, leading to more covalent bonds compared to the chlorine molecule. Hence, among the options provided, the chlorine molecule has the least number of covalent bonds.
Which of the following are the major parts of the nervous system?
- A. PNS and Somatic Nervous System
- B. Autonomic Nervous System and CNS
- C. PNS and CNS
- D. Autonomic Nervous System and Somatic Nervous System
Correct Answer: C
Rationale: The nervous system comprises two major parts: the peripheral nervous system (PNS) and the central nervous system (CNS). The PNS includes nerves outside the brain and spinal cord, while the CNS consists of the brain and spinal cord. Choice C (PNS and CNS) correctly identifies the primary divisions of the nervous system, encompassing both the peripheral and central components. Therefore, the correct answer is C.
In order to determine the effects of energy drinks on women's running speed, researchers gave 300 women an energy drink and then recorded the time it took each of them to run 2 miles. After collecting the results, researchers concluded that energy drinks increase the speed of running in women. Which of the following further tests would best help to support this conclusion? Repeat the same experiment, using 300 men.
- A. Repeat the experiment, giving half of the men water and the other half the energy drink.
- B. Repeat the experiment having half of the men run 2 miles and the other half run 5 miles.
- C. Repeat the experiment, giving the men two different energy drinks.
- D. Repeat the experiment, giving the men two different energy drinks.
Correct Answer: B
Rationale: To further support the conclusion that energy drinks increase running speed in women, the best approach would be to repeat the experiment with men. By having half of the men run 2 miles (similar to the original experiment with women) and the other half run a longer distance such as 5 miles, researchers can determine if the effects of energy drinks on running speed are consistent across different distances. This design allows for a comparative analysis between genders and varying running distances, providing a more comprehensive understanding of the impact of energy drinks on running performance.
Which substance protects the body from ultraviolet rays?
- A. Keratin
- B. Sebum
- C. Perspiration
- D. Melanin
Correct Answer: D
Rationale: Melanin is the pigment responsible for skin color and serves as a natural defense against ultraviolet (UV) rays. When the skin is exposed to UV rays, melanin production increases to absorb and dissipate the radiation, acting as a protective mechanism. This helps prevent DNA damage, reducing the risk of skin cancer and other UV-induced skin issues. Therefore, melanin is the substance that effectively shields the body from the harmful effects of UV radiation.