Nokea
A scientist needs 12 mL of a solution. They have a bottle with 0.12 L in it. Do they have enough?
- A. Yes, they have exactly what they need
- B. Yes, they have more than what they need
- C. No, they do not have enough
- D. None of the above
Correct Answer: B
Rationale: To convert 0.12 L to mL, you multiply by 1000 (since 1 L = 1000 mL). Therefore, 0.12 L = 120 mL. Since the scientist needs only 12 mL, the bottle contains more than enough solution, making choice B the correct answer.
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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.
Osmotic pressure is the tendency for a single solution to absorb what substance?
- A. Sodium.
- B. Water.
- C. Positive ions.
- D. Negative ions.
Correct Answer: B
Rationale: The correct answer is B: Water. Osmotic pressure is the pressure required to prevent the flow of water across a semipermeable membrane to achieve equilibrium. Water moves from a region of lower solute concentration to higher solute concentration to balance the concentration on both sides of the membrane. Therefore, the tendency for a solution to absorb water is what osmotic pressure refers to. Choices A, C, and D are incorrect because osmotic pressure is specifically related to the movement of water molecules, not sodium, positive ions, or negative ions.
What is the purpose of the mitochondria?
- A. Control the cell
- B. Generate energy
- C. Synthesize proteins
- D. Package waste for removal
Correct Answer: B
Rationale: The mitochondria's main function is to generate energy for the cell through the process of cellular respiration. This organelle is often referred to as the powerhouse of the cell due to its role in producing adenosine triphosphate (ATP), the cell's main energy currency. While other organelles are responsible for activities like controlling the cell (nucleus) or synthesizing proteins (ribosomes), the mitochondria's primary role is energy production.
Where in the cell does the Krebs cycle take place?
- A. mitochondrion.
- B. Nucleus.
- C. Cytoplasm.
- D. Chloroplast.
Correct Answer: A
Rationale:
What type of bond holds molecules of water together with other water molecules?
- A. Ionic
- B. Covalent
- C. Hydrogen
- D. Molecular
Correct Answer: C
Rationale: The correct answer is 'C: Hydrogen.' Molecules of water are held together by hydrogen bonds. These bonds form between the hydrogen atom of one water molecule and the oxygen atom of another water molecule. Hydrogen bonds are weaker than covalent bonds but are crucial in various biological processes, such as maintaining the unique properties of water and facilitating specific interactions in biological molecules.