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Questions and Answers
What is the primary factor that affects the rate of diffusion in osmosis and facilitated diffusion?
Which type of proteins are channel proteins examples of in facilitated diffusion?
In a scenario where a carrier protein is saturated, what impact does this have on the rate of facilitated diffusion?
Which of the following problems can arise from exposure to hypertonic solutions in animal cells?
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What is the color indicator used to detect the presence of starch in experiments involving dialysis bags?
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In a scenario where a high concentration gradient is present, what effect does this have on the rate of diffusion?
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How do hypotonic solutions affect plant cells?
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Study Notes
Passive Transport
- Occurs from high to low concentration without using energy
- Two types: Diffusion and Osmosis
Diffusion
- Rate of diffusion is affected by the steepness of the concentration gradient
- The steeper the gradient, the faster the rate of diffusion
Osmosis
- Rate of diffusion is affected by the steepness of the concentration gradient
- The steeper the gradient, the faster the rate of diffusion
Facilitated Diffusion
- Occurs through two types of protein channels: Channel proteins and Carrier proteins
- Channel proteins: allow passage of specific ions (e.g., Na+, Cl-) and water (e.g., Aquaporins)
- Carrier proteins: allow passage of specific molecules (e.g., glucose, amino acids)
- Rate of facilitated diffusion is affected by steepness of gradient and:
- Whether gated channels are open or closed (Channel proteins)
- Availability or saturation of the carrier (Carrier proteins)
- Graph of carrier proteins is similar to enzyme graph, with a similar shape and reason
Osmotic Pressure and Cell Effects
- Hypertonic solution: higher concentration outside the cell, leading to water loss and cell shrinkage
- Hypotonic solution: lower concentration outside the cell, leading to water gain and cell swelling
- Isotonic solution: equal concentration inside and outside the cell, no net water movement
- Effects on animal and plant cells:
- Turgor pressure: osmotic pressure that pushes the cell membrane against the cell wall
- Plasmolysis: plant cell shrinkage due to water loss
- Crenation: animal cell shrinkage due to water loss
- Lysis/Cell Bursting: cell rupture due to excessive water gain
Dialysis Bag Lab Demo
- Uses starch and iodine to demonstrate osmosis and diffusion
- Iodine is a color indicator for starch presence, turning purplish-black if starch is present
- Direction of flow can be determined by observing color change evidence
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Description
Test your knowledge on passive transport mechanisms such as diffusion, osmosis, and facilitated diffusion. Learn about how concentration gradients impact the rate of diffusion and the role of channel proteins in facilitating transport across membranes.
