Nokea
What is a characteristic of epithelial cells?
- A. Polarized
- B. Neutral
- C. Larger than other cells
- D. None of the above
Correct Answer: A
Rationale: Epithelial cells are polarized, meaning they have distinct apical and basal surfaces with different functions. This polarity is important for their specialized roles in absorption, secretion, and protection. Therefore, the correct answer is A: 'Polarized.' Choices B and C are incorrect as epithelial cells are not neutral and are not necessarily larger than other cells. Choice D is incorrect as epithelial cells do have specific characteristics.
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Which is an example of the comet organizational hierarchy for a wolf?
- A. Muscle tissue, blood cell, DNA, organ, circulatory system, wolf.
- B. Circulatory system, DNA, muscle tissue, blood cell, heart, wolf.
- C. Blood cell, organ, circulatory system, muscle tissue, DNA, wolf.
- D. DNA, blood cell, muscle tissue, heart, circulatory system, wolf.
Correct Answer: D
Rationale:
Where is DNA stored?
- A. The nucleus
- B. Ribosomes
- C. Endoplasmic reticulum
- D. Mitochondria
Correct Answer: A
Rationale: DNA, the genetic material of a cell, is stored within the nucleus. The nucleus serves as the control center of the cell and houses the DNA, which contains the instructions for building and maintaining the cell's structures and functions. Ribosomes are involved in protein synthesis, the endoplasmic reticulum plays a role in protein and lipid synthesis, while mitochondria are responsible for energy production through cellular respiration. Therefore, the correct answer is the nucleus where DNA is securely contained and regulated.
Why is the nucleus important in a cell?
- A. It stores the DNA.
- B. It provides structural support.
- C. It synthesizes proteins.
- D. It produces energy from food.
Correct Answer: A
Rationale: The correct answer is A. The nucleus is crucial in a cell because it stores the DNA, which contains the genetic information necessary for directing the cell's activities and determining its characteristics. The nucleus does not provide structural support, synthesize proteins, or produce energy from food; these functions are carried out by other cell organelles. Therefore, the main role of the nucleus is to safeguard and regulate the genetic material of the cell, ensuring proper cell function and inheritance of traits.
Which term means the movement of water across a semi-permeable membrane from a low solute concentration to a high solute concentration?
- A. Active Transport.
- B. Passive Transport.
- C. Osmosis.
- D. Diffusion.
Correct Answer: C
Rationale: The correct answer is C: Osmosis. Osmosis is the movement of water molecules across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration. This process occurs passively, without the need for energy input.
Rationale:
1. Osmosis specifically refers to the movement of water molecules.
2. It occurs across a semi-permeable membrane.
3. The direction of movement is from low solute concentration to high solute concentration.
4. Osmosis is a passive transport process, as it does not require energy.
Summary:
A: Active Transport involves the movement of molecules against the concentration gradient, requiring energy input.
B: Passive Transport includes processes like diffusion and osmosis but does not involve active energy expenditure.
D: Diffusion is the movement of molecules from high concentration to low concentration, not specific to water movement across a membrane.
Where is the apical side of an epithelial cell located?
- A. Is exposed to fluid or air
- B. Is on the top side of the cell
- C. Does not allow any substances to pass through
- D. None of the above
Correct Answer: B
Rationale: The apical side of an epithelial cell refers to the top surface of the cell that is exposed to the external environment, such as fluid or air. This surface is specialized to perform specific functions like absorption, secretion, or protection. The apical side faces the lumen or external environment and is crucial for the cell's interactions with its surroundings. Therefore, the correct answer is that the apical side of an epithelial cell is on the top side of the cell.