Nokea
What is the term for the chemical reaction that involves the loss of electrons?
- A. Reduction
- B. Oxidation
- C. Neutralization
- D. Precipitation
Correct Answer: B
Rationale: Oxidation is the process where a substance loses electrons. In an oxidation reaction, the substance being oxidized loses electrons, which are gained by another substance. Reduction is the opposite process, where a substance gains electrons. Neutralization is a reaction between an acid and a base to form a salt and water. Precipitation is the formation of a solid from a solution. Therefore, in the context of a chemical reaction involving the loss of electrons, the correct term is oxidation (Choice B).
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Which term refers to the resistance of a liquid to flow?
- A. Density
- B. Viscosity
- C. Surface tension
- D. Boiling point
Correct Answer: B
Rationale: Viscosity is the term that refers to the resistance of a liquid to flow. It is a measure of how thick or sticky a fluid is and determines how easily a liquid can flow. Density (A) is a measure of how much mass is contained in a given volume and is not related to the resistance of a liquid to flow. Surface tension (C) is the property of a liquid that allows it to resist an external force due to the cohesive nature of its molecules, but it is not directly related to the resistance of a liquid to flow. Boiling point (D) is the temperature at which a liquid changes to a vapor and is not a measure of the resistance of a liquid to flow.
Differentiate between gene therapy and genetic engineering in the context of human intervention.
- A. Gene therapy aims to modify existing genes within body cells, while genetic engineering manipulates genes in embryos to be passed on to offspring.
- B. Gene therapy focuses on treating genetic diseases, while genetic engineering enhances desirable traits or eliminates undesirable ones.
- C. Both involve directly altering the DNA sequence, but gene therapy targets somatic cells and genetic engineering modifies germline cells.
- D. There is no fundamental difference; both terms are synonymous.
Correct Answer: B
Rationale: A) Incorrect. Gene therapy does aim to modify existing genes within body cells, but genetic engineering does not necessarily manipulate genes in embryos to be passed on to offspring. Genetic engineering can involve modifying genes in any type of cell, not just embryos.
B) Correct. Gene therapy is a medical intervention that aims to treat genetic diseases by correcting or replacing faulty genes within an individual's body cells. On the other hand, genetic engineering involves modifying genes to enhance specific traits or eliminate undesirable ones, often in the context of agriculture or biotechnology.
C) Incorrect. While both gene therapy and genetic engineering involve altering DNA sequences, the distinction lies in the target cells. Gene therapy targets somatic cells (non-reproductive cells), while genetic engineering typically involves modifying germline cells (reproductive cells that can pass on genetic changes to offspring).
D) Incorrect. There is
Which type of cell has a nucleus but lacks membrane-bound organelles?
- A. Plant cell
- B. Prokaryotic cell
- C. Animal cell
- D. Fungal cell
Correct Answer: B
Rationale: The correct answer is B: Prokaryotic cell. Prokaryotic cells are characterized by having a nucleus that is not enclosed within a membrane (nuclear envelope) and lacking membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus. Plant, animal, and fungal cells are eukaryotic cells, which have a true nucleus enclosed within a nuclear envelope and contain membrane-bound organelles. Therefore, options A, C, and D are incorrect as they all represent eukaryotic cells that possess membrane-bound organelles.
Endotoxins are toxic substances released by:
- A. Viruses
- B. Bacteria (gram-positive)
- C. Bacteria (gram-negative)
- D. Parasites
Correct Answer: C
Rationale: Endotoxins are toxic substances that are part of the outer membrane of the cell wall of gram-negative bacteria. These toxins are released when the bacteria are destroyed or during bacterial growth. Endotoxins can cause a variety of harmful effects in the host, including fever, inflammation, and septic shock. Viruses do not produce endotoxins; they are typically associated with producing viral proteins that can be toxic to host cells. Gram-positive bacteria produce exotoxins, which are different from endotoxins found in gram-negative bacteria. Parasites, though capable of causing diseases, are not typically associated with the production of endotoxins.
Which term describes the ability of a substance to conduct electricity?
- A. Reactivity
- B. Density
- C. Conductivity
- D. Viscosity
Correct Answer: C
Rationale: Conductivity is the correct term used to describe the ability of a substance to conduct electricity. Reactivity is the measure of a substance's tendency to undergo chemical reactions. Density refers to the mass per unit volume of a substance, while viscosity is a measure of a fluid's resistance to flow. In the context of conducting electricity, conductivity is the most appropriate term as it directly relates to the substance's electrical conductive properties.