Biology
Form II
BIO-F2-02
✓ Verified TIE Syllabus
Transportation of Materials in Flowering Plants
Physiology of vascular transport in angiosperms: xylem and phloem structure, mechanisms of water and ion uptake, root pressure, transpiration pull, and factors controlling transpiration rate.
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🎯 Syllabus Competencies & Learning Objectives
Key Competencies
- Main: 1.0 Demonstrate mastery of the concepts, principles and processes of Biology
- Specific: 1.1 Describe the physiological, anatomical and ecological processes of living organisms
Specific Learning Objectives
- Describe the anatomy of xylem vessels and phloem sieve tubes.
- Explain the absorption of water by osmosis and mineral salts by active transport.
- Explain the forces causing movement of water up the xylem (root pressure, capillarity, transpiration pull).
- Define transpiration and state its physiological significance.
- Investigate environmental factors affecting transpiration rate using a potometer.
📖 Comprehensive Study Notes Summary
### Plant Transport System
#### Xylem vs Phloem
- **Xylem**: Dead, hollow, lignified vessels transporting water and dissolved mineral ions upward from roots to leaves.
- **Phloem**: Living sieve tube elements and companion cells transporting synthesized sucrose and amino acids bidirectionally (translocation).
#### Forces Driving Transpiration Pull
1. **Evaporation**: Water evaporates from mesophyll surfaces into air spaces and diffuses out through stomata.
2. **Cohesion & Adhesion**: Cohesion between polar water molecules forms continuous columns; adhesion attaches water molecules to hydrophilic xylem walls.
3. **Root Pressure**: Active pumping of ions into root stele draws water by osmosis.
#### Xylem vs Phloem
- **Xylem**: Dead, hollow, lignified vessels transporting water and dissolved mineral ions upward from roots to leaves.
- **Phloem**: Living sieve tube elements and companion cells transporting synthesized sucrose and amino acids bidirectionally (translocation).
#### Forces Driving Transpiration Pull
1. **Evaporation**: Water evaporates from mesophyll surfaces into air spaces and diffuses out through stomata.
2. **Cohesion & Adhesion**: Cohesion between polar water molecules forms continuous columns; adhesion attaches water molecules to hydrophilic xylem walls.
3. **Root Pressure**: Active pumping of ions into root stele draws water by osmosis.