Nokea
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.
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The covalent bonds between the monomers of an enzyme macromolecule are
- A. phosphodiester bonds
- B. glycosidic bonds
- C. ester bonds
- D. peptide bonds
Correct Answer: D
Rationale: Enzymes are proteins, and proteins are made up of amino acid monomers linked together by peptide bonds. Therefore, the covalent bonds between the monomers of an enzyme macromolecule are peptide bonds.
A researcher writes a grant proposal to replicate an experiment recently published by another researcher. Which statement best supports the grant proposal?
- A. Funding this critical research will benefit science in the long term.
- B. Replicating the published work will provide independent confirmation of the results.
- C. Funding this grant proposal will allow this laboratory to further study this topic.
- D. Replicating published work with altered variables will extend the previous results.
Correct Answer: B
Rationale: Choice B is the correct answer as it emphasizes the significance of independent verification of research findings through replication. Replicating experiments is a fundamental part of the scientific method to ensure the credibility and accuracy of results. It plays a crucial role in validating the original outcomes and contributes to establishing a strong scientific knowledge base. By replicating the published work, the researcher aims to confirm the validity and reliability of the initial findings, which is essential for building upon existing knowledge and advancing scientific understanding.
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 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.
What is a common cause of a tsunami?
- A. Earthquakes
- B. Sunspot activity
- C. Lightning strikes
- D. Flooding
Correct Answer: A
Rationale: Earthquakes are a common cause of tsunamis. When an earthquake occurs under the ocean, it can displace a large volume of water, triggering a series of powerful waves known as a tsunami. Sunspot activity, lightning strikes, and flooding do not directly cause tsunamis. Therefore, the correct answer is earthquakes, as they are the primary geological event that leads to the formation of tsunamis.