Nokea
What action does an enzyme perform that increases the rate of a biological reaction?
- A. Lowers the activation energy.
- B. Removes the energy barrier.
- C. Changes the substrate.
- D. Alters the active site.
Correct Answer: A
Rationale: Correct Answer: A - Lowers the activation energy.
Rationale:
1. Enzymes lower activation energy needed for a reaction to occur by stabilizing the transition state.
2. This accelerates the reaction rate without being consumed in the process.
3. Choice B is incorrect as enzymes do not physically remove the energy barrier.
4. Choice C is incorrect as enzymes do not change the substrate but rather facilitate the reaction.
5. Choice D is incorrect as enzymes do not alter their active sites during reactions; the sites remain unchanged.
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If a hard-boiled egg is placed in a beaker of saltwater, what will happen to the egg?
- A. Expand because water will move into the egg
- B. Shrivel because water will leave the egg
- C. Remain the same
- D. None of the above
Correct Answer: B
Rationale: When a hard-boiled egg is placed in a beaker of saltwater, the egg will shrivel because water will move out of the egg due to osmosis. Osmosis is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. In this case, the saltwater has a higher solute concentration than the egg, causing water to move out of the egg, leading to shrinkage or shriveling.
What is the term for movement of water across a cellular membrane?
- A. Osmosis.
- B. Facilitated diffusion.
- C. Diffusion.
- D. Active transport.
Correct Answer: A
Rationale: Correct Answer: A - Osmosis
Rationale:
1. Osmosis is the movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration.
2. Water moves passively to equalize solute concentrations on both sides of the membrane.
3. Facilitated diffusion (B) involves the use of transport proteins, not specific to water movement.
4. Diffusion (C) is the movement of solutes, not specific to water.
5. Active transport (D) requires energy to move molecules against their concentration gradient, different from osmosis.
In the scenario presented in question #49, what type of solution is the egg immersed in?
- A. Hypertonic
- B. Isotonic
- C. Hypotonic
- D. None of the above
Correct Answer: A
Rationale: When an egg is placed in a hypertonic solution, water moves out of the egg into the surrounding solution due to the higher concentration of solutes outside the egg. This results in the egg shrinking or shriveling up as water leaves it, indicating a hypertonic environment.
Which method of glucose conversion generates the most usable and efficient form of ATP within the human body?
- A. Lactic acidosis.
- B. Fermentation conversion.
- C. Anaerobic respiration.
- D. Aerobic respiration.
Correct Answer: D
Rationale:
Which of the following describes how a bacterium reproduces?
- A. Mitosis
- B. Meiosis
- C. Binary fission
- D. Cytokinesis
Correct Answer: C
Rationale: Binary fission is the correct answer. Bacteria reproduce asexually through binary fission, where a single cell divides into two identical daughter cells. Mitosis and meiosis are processes that occur in eukaryotic cells, not bacteria. Cytokinesis is the physical division of the cytoplasm that follows nuclear division, which is a part of the cell cycle in both eukaryotic and prokaryotic cells but not specific to bacterial reproduction.