Overview
This lecture explains how the roots, stem, and leaves function together as a transport system in plants to move water, nutrients, and food throughout the organism.
Roots: Absorption and Transport
- Roots absorb water and minerals from the soil using tiny hair-like structures.
- Roots anchor and support the plant and also store food.
- Water and minerals are passed into the plant’s vascular system, mainly the xylem.
- Absorption uses processes like capillary action and osmosis.
Stem: Structure and Transport Highway
- The stem holds the plant upright and provides structural support.
- The stem transports water and minerals upward through the xylem.
- It also moves food made in the leaves down through the phloem.
- The vascular bundle in the stem contains both xylem (center) and phloem (outer part).
Leaves: Food Production and Distribution
- Leaves perform photosynthesis, using sunlight, carbon dioxide, and water to make glucose.
- Glucose and other nutrients are transported throughout the plant via the phloem.
- The leaves send food to all parts of the plant, supporting new growth.
Vascular System: Xylem and Phloem
- Xylem consists of elongated dead cells with tough, lignin-rich walls; it moves water and minerals up.
- Phloem is made of living cells and transports sucrose and amino acids in both directions.
- Movement of substances in the phloem is called translocation.
How Plant Organs Work Together
- Roots, stems, and leaves collaborate to ensure the plant receives water, minerals, and food.
- Each part has a specialized role but functions as a team in the plant’s transport system.
Key Terms & Definitions
- Root — organ that absorbs water/minerals and anchors the plant.
- Stem — supports the plant and transports fluids between roots and leaves.
- Leaf — organ responsible for photosynthesis, producing glucose for the plant.
- Xylem — vascular tissue that transports water and minerals from roots to leaves.
- Phloem — vascular tissue that moves food (sucrose, amino acids) through the plant.
- Translocation — movement of food substances in the phloem.
- Photosynthesis — process where leaves use sunlight, CO₂, and water to make glucose.
Action Items / Next Steps
- Review the functions of xylem and phloem.
- Study diagrams of plant vascular bundles.
- Prepare to describe how roots, stems, and leaves work together in plant transport.