Plant Cell Organisation
How Are Plants Organised?
Just like in animals, plant cells are organised into tissues, which form organs, which work together in organ systems to carry out key life processes – such as photosynthesis, transport, and growth.
💡 Key Concept: A plant’s structure is adapted for efficient transport of substances and maximum light absorptionfor photosynthesis.
Plant Tissues and Their Functions
Tissue | Function |
Epidermal tissue | Covers the plant and protects it. Often transparent to let light through. |
Palisade mesophyll | Contains lots of chloroplasts – main site of photosynthesis |
Spongy mesophyll | Loosely packed with air spaces for gas exchange |
Xylem | Transports water and mineral ions from the roots → up the plant |
Phloem | Transports sugars (mainly sucrose) made in the leaves → rest of the plant |
Meristem tissue | Found at growing tips of roots and shoots – contains undifferentiated cells for growth |
The Leaf – A Plant Organ
The leaf is designed for efficient photosynthesis:
- Large surface area
- Thin – short diffusion distance
- Chloroplast-rich palisade cells
- Air spaces in spongy mesophyll
- Veins containing xylem and phloem
- Stomata to allow gas exchange
Xylem and Phloem – Transport Tissues
🔹 Xylem
✔ Carries water and mineral ions from the roots to leaves
✔ Made of dead cells joined end-to-end
✔ Strengthened with lignin
✔ Movement is one-way only
🔹 Phloem
✔ Carries dissolved sugars from the leaves to the rest of the plant
✔ Made of living cells with small holes in the end walls
✔ Movement is both directions (called translocation)
Questions
- What is the function of palisade mesophyll?
- What does xylem transport?
- Name the tissue that carries sugars around the plant.
- What is the function of the epidermis?
- Where is meristem tissue found?
Summary
- Plant tissues form organs like leaves and roots, which work together in a transport system.
- Xylem and phloem transport essential substances around the plant.
- The leaf is a specialised organ adapted for efficient photosynthesis.