Plant Processes: Photosynthesis & Transport
How plants manufacture food and transport fluids through vascular tissue.
Plants are photoautotrophs that synthesize glucose from inorganic carbon dioxide and water using light energy. Transport of water and minerals occurs through xylem, while organic food is translocated via phloem.
Gas exchange in leaves is regulated by microscopic pores called stomata. Stomatal opening and closing are driven by water movement into and out of specialized guard cells.
Key Takeaways
- •Photosynthesis occurs in chloroplasts and has two phases: Light Reactions (thylakoid) and Dark Reactions (stroma).
- •Guard cells swell (become turgid) and open the stomatal pore when water enters them.
- •Transpiration creates a suction pull (transpiration pull) that raises water from roots to leaves.
Core Concepts & Definitions
1Stomatal Opening and Closing Mechanism
When water flows into guard cells, they swell and curve outward due to uneven wall thickness, opening the stomatal pore. When guard cells lose water, they shrink and flatten, closing the pore to prevent water loss.
•Vascular transport is divided: Xylem (unidirectional, passive pull) and Phloem (bidirectional, active translocation using ATP).
•[INSERT: Diagram showing open vs closed stomata guard cells]
Quick Revision Notes
- •Always verify units and maintain coordinate systems.
- •Check boundary conditions and reference variables before applying formulas.
- •Ensure decimal precision is correct on output results.
Equations & Calculation Methods
Step-by-Step Worked Examples
Tracking Water Potential Movement
Problem: Describe the step-by-step pathway of water transport from soil into a leaf cell.
Step-by-step Solution:
- 1Soil water enters root hair cells via osmosis due to active ion accumulation in roots.
- 2Water travels across root cortex cells to reach the xylem vessels.
- 3Water is pulled upward through the stem xylem due to the negative pressure created by transpiration in the leaves (transpiration pull).
- 4Water exits leaf veins and enters mesophyll cells for use in photosynthesis.
Topic FAQ
As water molecules evaporate from stomata in leaves, cohesion-adhesion forces pull a continuous column of water upward through the xylem, stretching from roots to leaves.
Related Topics
Lab Experiment: Testing Need for Light in Photosynthesis (Starch Test)
Required Materials
- Potted plant
- Black paper strip
- Paper clips
- Ethanol
- Iodine solution
- Beaker
- Water bath
Procedure Steps
- 1Place a potted plant in a dark room for 48 hours to destarch the leaves.
- 2Clip a strip of black paper across a portion of one leaf on both sides.
- 3Place the plant in bright sunlight for 6 hours.
- 4Pluck the leaf, remove the black paper, and boil the leaf in water, then in ethanol in a water bath to remove chlorophyll.
- 5Rinse the bleached leaf in water and flood it with iodine solution.
Practice Quiz & Interactive Assessment
Syllabus Review Mode
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Printable Worksheet: Guard Cells and Transpirational Water Flow
Classroom Homework Questions
- Q1.Write the balanced equation for photosynthesis. State three events that occur during this process.
- Q2.Explain the mechanism of stomatal opening and closing with diagrams.
- Q3.Distinguish between transport in xylem and transport in phloem.
- Q4.What is translocation? How does it occur in plants using active transport?
Frequently Asked Questions
As water molecules evaporate from stomata in leaves, cohesion-adhesion forces pull a continuous column of water upward through the xylem, stretching from roots to leaves.