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Questions and Answers
Which statement correctly describes selective permeability of the cell membrane?
What is true about the Fluid Mosaic Model of the cell membrane?
Which of the following is NOT a characteristic of the cell wall?
What type of transport requires energy to move substances across the membrane?
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What function does the Middle Lamella serve in plant cells?
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Study Notes
Cell Membrane
- The fluid mosaic model describes the cell membrane as a fluid lipid bilayer with embedded proteins.
- Proposed by Singer and Nicolson.
- Membrane fluidity is crucial for cell growth, secretion, endocytosis, and cell division.
- Passive transport across the membrane does not require energy and includes simple diffusion and facilitated diffusion.
- Active transport requires energy (ATP) and moves substances against their concentration gradient, like the Na+/K+ pump.
- The cell membrane exhibits selective permeability, allowing certain molecules to pass through while restricting others.
Cell Wall
- A rigid, non-living structure found in plants, fungi, and some algae.
- Provides shape, protection, and cell-to-cell communication.
- Composed of cellulose, hemicellulose, pectins, and proteins, with varying components depending on the organism.
- Two types:
- Primary wall: thin and flexible
- Secondary wall: thicker and rigid
- The middle lamella is a layer between the cell walls of adjacent cells, holding them together.
- Plasmodesmata are channels that connect the cytoplasm of neighboring cells.
Additional Points
- The endomembrane system is a network of organelles involved in protein synthesis, modification, and transport.
- Organelles are key structures within cells, each with specific functions, such as the nucleus, mitochondria, ribosomes, and Golgi apparatus.
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Description
This quiz covers the fundamental concepts of the cell membrane and cell wall. It includes details on the fluid mosaic model, transport mechanisms, and the composition and function of the cell wall in various organisms. Test your knowledge of these essential biological structures!
