Chapter 15: Transport Systems in Organisms

What is the primary factor that influences the rate of diffusion?

Which type of membrane allows only certain molecules to pass through?

What type of solution would cause a plant cell to swell due to osmosis?

What happens to an animal cell when it is placed in a diluted solution?

What is the term for the movement of water molecules from high water potential to low water potential through a partially permeable membrane?

What is the primary function of osmosis in cells?

What would happen to a red blood cell placed in a concentrated salt solution?

What is the primary function of active transport in living organisms?

Why can't glucose molecules move into cells via osmosis?

Which of the following is an example of osmosis in plant cells?

What is the main difference between diffusion and osmosis?

What is the characteristic of the cell membrane that allows osmosis to occur?

Which of the following is NOT an example of transport across a cell membrane?

Transport Systems in Organisms

Diffusion

Definition: Movement of particles from high concentration to low concentration, down a concentration gradient
Influenced by the concentration gradient; steeper gradient results in faster diffusion
Occurs in gases, liquids, and dissolved substances, with or without a membrane
Types of membranes:
- Fully Permeable: All molecules can pass through
- Impermeable: No molecules can pass through
- Partially Permeable: Only certain molecules can pass through
Examples in living organisms:
- Gas exchange in lungs
- Nutrient absorption in intestines

Osmosis

Definition: Net movement of water molecules from a region of high water potential to low water potential through a partially permeable membrane
Water potential gradient influences the rate of osmosis
Water potential:
- High: More water molecules, less solute concentration
- Low: Fewer water molecules, higher solute concentration
Osmosis in living systems:
- Animal Cells (e.g., red blood cells):
  - In diluted solution: Water enters the cell, causing it to swell and possibly burst
  - In concentrated solution: Water leaves the cell, causing it to shrink and crenate
- Plant Cells:
  - In diluted solution: Water enters the cell, making it turgid
  - In concentrated solution: Water leaves the cell, causing plasmolysis

Transport Across Cell Membrane

Diffusion: e.g., oxygen uptake and carbon dioxide excretion during respiration
Osmosis: e.g., water uptake by root hair cells
Active Transport: e.g., uptake of mineral salts by root hair cells, glucose, and amino acids by epithelial cells in the small intestine

This quiz covers the concepts of diffusion, types of membranes, and transport systems in organisms, including the movement of particles and molecules across membranes.