key term - Passive Transport

Definition

Passive transport is the movement of substances across a cell membrane without the need for energy input from the cell. This process relies on concentration gradients, where molecules move from areas of higher concentration to areas of lower concentration, facilitating the transport of water and solutes in plant cells and influencing their overall water relations and transport mechanisms.

5 Must Know Facts For Your Next Test

1. Passive transport does not require ATP or any other energy sources; it solely depends on the kinetic energy of molecules.
2. There are different types of passive transport including simple diffusion, facilitated diffusion, and osmosis, each playing a crucial role in cellular processes.
3. In plants, passive transport is vital for maintaining turgor pressure, which is essential for structural support and growth.
4. The rate of passive transport can be influenced by factors like temperature, molecule size, and membrane permeability.
5. Plants utilize passive transport mechanisms to absorb water and nutrients from the soil through root cells, essential for their overall health.

Review Questions

• How does passive transport facilitate the movement of water and nutrients in plant cells?
  • Passive transport allows water and nutrients to move through plant cell membranes by relying on concentration gradients. Water moves through osmosis, where it travels from areas of low solute concentration in the soil to areas of higher solute concentration inside the root cells. This mechanism ensures that plant cells can effectively absorb necessary nutrients and maintain proper hydration without expending energy.
• Compare and contrast passive transport with active transport in terms of energy use and mechanisms.
  • Passive transport differs from active transport in that it does not require cellular energy to move substances across membranes; it relies on natural concentration gradients. While passive transport involves simple diffusion or facilitated diffusion through channels like aquaporins, active transport requires ATP to move molecules against their concentration gradients. Understanding these differences is key to grasping how plants regulate internal conditions and respond to environmental changes.
• Evaluate the significance of aquaporins in facilitating passive transport in plant cells, particularly during drought conditions.
  • Aquaporins play a crucial role in passive transport by allowing rapid movement of water molecules into and out of plant cells. During drought conditions, efficient water uptake becomes vital for plant survival; aquaporins enable this process to occur quickly without energy expenditure. Their function helps maintain cellular turgor pressure, thus supporting physiological processes like nutrient uptake and photosynthesis, while also influencing how plants adapt to water scarcity.

Related terms

Diffusion:

The process by which molecules spread from an area of high concentration to an area of low concentration until equilibrium is reached.

Osmosis:

The specific type of passive transport that involves the movement of water across a selectively permeable membrane, driven by differences in solute concentration.

Aquaporins:

Specialized channel proteins in cell membranes that facilitate the rapid transport of water molecules during osmosis.