1. What must any solution injected into tissues be to prevent cells from shrinking or swelling?
A. Distilled.
B. Hypertonic.
C. Hypotonic.
D. Isotonic. Correct
Explanation
The correct answer is D: Isotonic. An isotonic solution has the same concentration of solutes as the cells in the tissues, preventing them from shrinking or swelling. If a solution is hypertonic (choice B), it has a higher solute concentration and would cause cells to shrink due to water leaving the cells. A hypotonic solution (choice C) has a lower solute concentration and would cause cells to swell as water enters the cells. Distilled water (choice A) lacks solutes and would cause cells to swell. Overall, an isotonic solution maintains cell volume and prevents any osmotic imbalances.
2. What structure in a plant cell is surrounded by a double membrane and contains most of the genetic information used to control the cell?
A. Mitochondrion
B. Nucleus. Correct
C. Chromatin.
D. Chromosome.
Explanation
Rationale: The correct answer is B: Nucleus. The nucleus is surrounded by a double membrane and contains most of the genetic information in the form of DNA, which controls the cell's activities. Mitochondria (A) are involved in energy production, chromatin (C) is a complex of DNA and proteins within the nucleus, and chromosomes (D) are condensed structures of DNA found in the nucleus during cell division. Therefore, the nucleus is the structure that fits the description provided in the question.
3. Osmotic pressure is the tendency for a single solution to absorb what substance?
A. Sodium.
B. Water. Correct
C. Positive ions.
D. Negative ions.
Explanation
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.
4. Skin cells undergo what type of cellular division?
A. Melosis.
B. Binary fission.
C. Sexual reproduction.
D. Mitosis. Correct
Explanation
The correct answer is D: Mitosis. Skin cells undergo mitosis, a type of cellular division where a parent cell divides into two identical daughter cells. During mitosis, the genetic material is equally distributed between the daughter cells to ensure genetic stability. Melosis (A) is incorrect as it refers to the type of cell division that occurs during sexual reproduction to produce gametes. Binary fission (B) is incorrect as it is a form of asexual reproduction seen in prokaryotes. Sexual reproduction (C) is incorrect as it involves the fusion of gametes from two different parents to produce genetically diverse offspring, not the division of existing cells like in skin cells. In summary, mitosis is the correct choice for skin cell division as it maintains genetic continuity and ensures tissue growth and repair.
5. A plant cell is placed in a solution and it shrinks from water loss. In what type of environment was the cell placed?
A. Plasmolytic
B. Hypertonic. Correct
C. Hypotonic.
D. Isosmotic.
Explanation
Correct Answer: B - Hypertonic
Rationale:
1. A hypertonic solution has a higher solute concentration than the cell, causing water to move out of the cell by osmosis.
2. Water loss results in the cell shrinking, as observed in this scenario.
3. Plasmolytic refers to the process of cytoplasm shrinking due to water loss in a hypertonic environment.
4. Hypotonic and isosmotic environments would not cause the cell to shrink from water loss.