Vascular Plant Transport

Plant Transport

Root need sugarLeaf make sugarLeaf need waterRoot have water

Water go upSugar go down

Root and Leaf shareRoot and Leaf are friends

Transpiration

Transpiration: water transport

The controlled release of water from a plant through stomata on the leaves resulting in movement of water from roots to leaves

1. Water evaporates from spongy mesophyll2. Creates low water pressure in leaves3. Roots absorb water by osmosis4. Creates high water pressure in roots5. Water moves from high to low pressure

• From root to leaf

Xylem Transport

• Water moves by a variety of forces– Cohesion:

• H-bonding to other water– Adhesion:

• H-bonding to walls of xylem– Capillary Action:

• Passive movement of water up through a narrow tube against gravity

– Transpiration pull: • suction pressure from leaves

Factors Affecting Rate of Transpiration

• Sunny – increased light intensity– Stomata open in presence of sunlight

• Warm – high temperature– Increased evaporation

• Dry – low humidity– Increase water vapor conc. gradient

• Windy– Removes established humid locations around

stoma

Regulation of Transpiration

• Guard Cells surrounding the stoma swell or shrink in response to the plants water needs.

• Up to 90% of water loss is through stoma• Amount of water loss depends on density of stoma and

their relative size.

Stoma close when guard cells lose water

• Flaccid state: K+ ions are transported out of the cell, water follows by osmosis

• Turgor state: K+ ions are transported into guard cells, water follows by osmosis

Abscisic Acid

• Plant hormone produced by root in response to water deficiency

• Stimulates guard cells into flaccid state, stoma closed

Xerophyte Adaptations

• Metabolic machinery can withstand increased temperature

• Low stoma densities• Small, thick leaves (spines)– Reduces surface area to volume ratio

• Thicker cuticles• CAM physiology– C02 absorbed at night, not day

• Explain the process of water transport in vascular plants from root to leaf.– Include tissues water moves through– Forces that influence water movement– Need for water movement

Phloem Transport• Phloem is composed of living sieve tubes

1. Sugars produced in leaves are actively pumped into sieve tubes

2. Water follows by osmosis3. Results in high pressure in phloem4. Sugars exit phloem in roots and branch tips5. Results in low pressure in phloem6. Phloem solution moves from high pressure area to low

• From leaf to root, root to leaf

• Translocation is the movement of a biochemical in phloem

Phloem Transport