Nokea
Which component of an atom has relatively little mass that is considered negligible when calculating the atomic mass number?
- A. Neutron
- B. Proton
- C. Electron
- D. Quark
Correct Answer: C
Rationale: The correct answer is C: Electron. Electrons have significantly less mass compared to protons and neutrons, making their contribution to the atomic mass number negligible. When calculating the atomic mass, the mass of electrons is typically not factored in due to their minimal mass compared to the other components of the atom. While protons and neutrons contribute significantly to the atomic mass number, electrons, due to their much smaller mass, are considered to have a negligible impact on the overall calculation. Therefore, electrons can be disregarded when determining the atomic mass of an atom.
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Which of the following organic molecules contains both an amine and a carboxyl group?
- A. Lipids
- B. Cellulose
- C. Chitin
- D. Proteins
Correct Answer: D
Rationale: Proteins are composed of amino acids, which contain both an amine (NH2) and a carboxyl (COOH) functional group. The amine group is found at one end of the amino acid molecule, while the carboxyl group is located at the other end. When amino acids join together through peptide bonds, the amine of one amino acid reacts with the carboxyl group of another, forming a protein chain. Therefore, the correct answer is proteins.
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 of the following is the process in which an ovarian follicle matures and releases a reproductive egg?
- A. Menstruation
- B. Ovulation
- C. Fertilization
- D. Oogenesis
Correct Answer: B
Rationale: Ovulation is the correct answer as it is the process where an ovarian follicle matures and releases a reproductive egg. Menstruation refers to the shedding of the uterine lining, fertilization is the union of sperm and egg, and oogenesis is the formation of female gametes. Ovulation is a crucial step in the reproductive cycle as it allows for the release of a mature egg from the ovary, which can then potentially be fertilized during its journey through the fallopian tube. Understanding these definitions is essential for comprehending the sequence of events in the female reproductive system.
In a phase diagram, what term is used for a substance held at a temperature and pressure where solid, liquid, and gaseous states of a substance exist simultaneously?
- A. critical temperature
- B. triple point
- C. absolute zero
- D. critical point
Correct Answer: B
Rationale: The point described in the question is called the triple point. At the triple point, all three phases of a substance (solid, liquid, and gas) coexist in equilibrium. The critical temperature is the highest temperature at which a distinct liquid phase can form, while absolute zero is the lowest possible temperature. The critical point is the point on a phase diagram that represents the highest temperature and pressure at which a distinct liquid and gas phase can coexist. Therefore, the correct answer is the triple point, where all three phases coexist.
Which laboratory method is most useful to separate genomic DNA fragments by size?
- A. Titration
- B. Spectrophotometry
- C. Electrophoresis
- D. Filtration
Correct Answer: C
Rationale: Electrophoresis is the most suitable laboratory method for separating genomic DNA fragments by size. It works by subjecting DNA fragments to an electric field, causing them to migrate through a gel matrix based on size differences. Smaller fragments move faster and travel farther than larger ones, allowing for separation and analysis based on size. Titration is a technique used to determine the concentration of a solution, not to separate DNA fragments by size. Spectrophotometry is used to measure the amount of light absorbed by a substance at different wavelengths, not for DNA fragment size separation. Filtration is a method used to separate solid particles from a liquid or gas by passing it through a filter medium, not for separating DNA fragments by size.