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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.

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What is the function of the myelin sheath for a nerve cell?

  • A. Sensory perception
  • B. Insulation
  • C. Nutrition
  • D. Regeneration
Correct Answer: B

Rationale: The myelin sheath functions as an insulator for nerve cells, enabling the rapid transmission of electrical impulses along the nerve fiber. This insulation is essential for maintaining the speed and efficiency of nerve signal conduction. Sensory perception involves detecting sensory stimuli, nutrition involves the supply of nutrients, and regeneration is the process of regrowth or repair, which are distinct functions from what the myelin sheath provides.

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.

Which laboratory method is most useful for separating genomic DNA fragments by size?

  • A. Titration
  • B. Spectrophotometry
  • C. Electrophoresis
  • D. Filtration
Correct Answer: C

Rationale: Electrophoresis is the most suitable method for separating genomic DNA fragments by size. In electrophoresis, DNA fragments are separated based on their size through an electric field. The smaller fragments move faster towards the positive electrode, while the larger fragments move slower, allowing for differentiation based on size. Titration is a technique used to determine the concentration of a substance in a solution, not for separating DNA fragments. Spectrophotometry is a method used to measure how much a substance absorbs light at different wavelengths, not for separating DNA fragments. Filtration is a process of separating solids from liquids using a filter, not commonly used for separating DNA fragments by size.

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 properties of water explains its solvent abilities for certain substances?

  • A. High specific heat
  • B. Polarity
  • C. Volume
  • D. High surface tension
Correct Answer: B

Rationale: The correct answer is B: Polarity. Water's polarity, resulting from its unequal sharing of electrons and the formation of hydrogen bonds, makes it an excellent solvent. The polar nature of water allows it to interact with and dissolve substances that have charges or partial charges, aiding in their breakdown at a molecular level. Choices A, C, and D are not directly associated with water's solvent capabilities. High specific heat (Choice A) refers to water's ability to resist temperature changes, volume (Choice C) is the amount of space occupied by water, and high surface tension (Choice D) pertains to water's cohesive properties.

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