Plant Biology Chapter: Transpiration Stream and Osmoregulation

Transpiration Stream

• The transpiration stream is the flow of water from the roots to the leaves and then to the atmosphere as water vapor
• It is driven by the evaporation of water from the leaves, which creates a negative pressure that pulls water up the plant
• The transpiration stream is responsible for:
  • Water transport
  • Nutrient transport
  • Temperature regulation
  • Maintaining turgor pressure

Osmoregulation

• Osmoregulation is the process by which plants regulate their internal solute concentration to maintain proper water balance
• Plants use osmoregulation to:
  • Maintain turgor pressure
  • Regulate water uptake
  • Prevent water loss
  • Adapt to changing environmental conditions
• Osmoregulation is achieved through the control of solute concentrations and the movement of water into and out of cells

Xylem Structure

• Xylem is a type of vascular tissue responsible for water and mineral transport
• Xylem consists of:
  • Tracheids: dead cells that provide a pathway for water transport
  • Vessel elements: dead cells that form a continuous tube for water transport
  • Xylem parenchyma: living cells that store water and minerals
• Xylem structure allows for:
  • Efficient water transport
  • Mechanical support
  • Protection from pathogens

Phloem Function

• Phloem is a type of vascular tissue responsible for sugar transport
• Phloem functions include:
  • Transporting sugars produced by photosynthesis from leaves to the rest of the plant
  • Transporting hormones and other signaling molecules
  • Providing nutrients to growing tissues
• Phloem is composed of:
  • Sieve cells: specialized cells that transport sugars
  • Companion cells: cells that provide energy and support to sieve cells

Root Pressure

• Root pressure is the pressure exerted by the roots of a plant to push water up the xylem
• Root pressure is generated by:
  • Osmosis: the movement of water into the root cells
  • Active transport: the movement of ions into the xylem
• Root pressure helps to:
  • Push water up the xylem against gravity
  • Regulate water transport
  • Maintain turgor pressure in the plant

Transpiration Stream

• The transpiration stream is the flow of water from the roots to the leaves and then to the atmosphere as water vapor
• It is driven by the evaporation of water from the leaves, which creates a negative pressure that pulls water up the plant
• The transpiration stream is responsible for water transport, nutrient transport, temperature regulation, and maintaining turgor pressure

Osmoregulation

• Osmoregulation is the process by which plants regulate their internal solute concentration to maintain proper water balance
• Plants use osmoregulation to maintain turgor pressure, regulate water uptake, prevent water loss, and adapt to changing environmental conditions
• Osmoregulation is achieved through the control of solute concentrations and the movement of water into and out of cells

Xylem Structure

• Xylem is a type of vascular tissue responsible for water and mineral transport
• Xylem consists of tracheids, vessel elements, and xylem parenchyma
• Tracheids are dead cells that provide a pathway for water transport
• Vessel elements are dead cells that form a continuous tube for water transport
• Xylem parenchyma are living cells that store water and minerals
• Xylem structure allows for efficient water transport, mechanical support, and protection from pathogens

Phloem Function

• Phloem is a type of vascular tissue responsible for sugar transport
• Phloem functions include transporting sugars produced by photosynthesis from leaves to the rest of the plant
• Phloem transports hormones and other signaling molecules
• Phloem provides nutrients to growing tissues
• Phloem is composed of sieve cells and companion cells
• Sieve cells are specialized cells that transport sugars
• Companion cells are cells that provide energy and support to sieve cells

Root Pressure

• Root pressure is the pressure exerted by the roots of a plant to push water up the xylem
• Root pressure is generated by osmosis and active transport
• Osmosis is the movement of water into the root cells
• Active transport is the movement of ions into the xylem
• Root pressure helps to push water up the xylem against gravity, regulate water transport, and maintain turgor pressure in the plant