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Questions and Answers
What is the function of microvilli in epithelial cells?
Which cell modification is primarily involved in the adhesion of epithelial cells to basement membranes?
How do cilia contribute to the function of epithelial cells?
What role do gap junctions play in cells?
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What structure is secreted by cells on their apical surface to form the extracellular matrix (ECM)?
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Which type of plant cell is specialized for the absorption of water and minerals?
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What is the primary function of tight junctions in epithelial cells?
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Which of the following statements about specialized cells in multicellular organisms is correct?
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What is the primary function of phloem in plants?
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What role do guard cells play in a plant's leaf?
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Why do red blood cells not contain a nucleus?
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What is a primary feature of muscle cells?
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What is the primary responsibility of epithelial cells?
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Study Notes
Cell Modifications
- Apical Modification: Occurs on the top surface of a cell; involves structures such as cilia, flagella, villi, microvilli, and pseudopods.
- Cilia: Short hair-like structures that move in wave-like motions to assist in environments like respiratory tracts.
- Flagella: Long, whip-like structures primarily responsible for motility in cells such as sperm.
- Villi: Finger-like projections that increase the surface area in organs, enhancing absorption efficiency.
- Microvilli: Smaller projections on cell surfaces to further increase absorption capability.
- Pseudopods: Irregular, temporary extensions of amoebas and some eukaryotic cells, aiding in movement and prey engulfment.
- Extra Cellular Matrix (ECM): Compound secreted by cells, primarily composed of glycoproteins in animals, with a cell wall serving this purpose in plants.
Basal and Lateral Modifications
- Basal Modification: Found on the bottom surface of cells, featuring desmosomes and hemidesmosomes.
- Desmosomes: Junctions that aid in cell adhesion among epithelial cells.
- Hemidesmosomes: Junctions that anchor epithelia to underlying basement membranes.
- Lateral Modification: Occurs on the side surfaces of cells; includes tight junctions, adherens junctions, and gap junctions.
- Tight Junction: Forms a barrier regulating water and solute movement, preventing leakage of extracellular fluid.
- Adherens Junction: Initiates and stabilizes cell-cell adhesion; also involved in cytoskeletal regulation and signaling.
- Gap Junction: Channels between cells that allow direct exchange of ions and small molecules, facilitating communication.
Specialized Cells in Multicellular Organisms
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Begin as a single fertilized egg, developing into trillions of specialized cells performing unique functions.
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Specialized Plant Cells:
- Root Cells: Absorb minerals and water; elongate to form root hairs, increasing surface area and stability.
- Xylem: Transports water from roots upwards.
- Phloem: Distributes nutrients bidirectionally throughout the plant.
- Guard Cells: Regulate gas exchange and water transpiration at leaf stomata.
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Specialized Animal Cells:
- Red Blood Cells: Transport oxygen throughout the body; lack a nucleus for efficient transportation.
- Muscle Cells: Long and fibrous, enabling contraction for movement and organ function.
- Epithelial Cells: Line exterior and interior body surfaces, responsible for skin formation and new cell generation.
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Description
Explore the various modifications of cells presented in Biology Lesson 3. This quiz focuses on apical modifications, including cilia, flagella, villi, and microvilli, analyzing their structures and functions in enhancing absorption. Test your knowledge on these essential biological concepts.
