Quick Summary
Plant Anatomy and Plant Physiology connects structure with function. Study this chapter through tissues, root and stem anatomy, photosynthesis, transpiration, and diagrams.
Key Definitions
- Plant anatomy: Study of internal plant structure.
- Tissue: Group of cells with similar structure and function.
- Xylem: Conducts water and minerals from roots to other parts.
- Phloem: Conducts prepared food from leaves to other parts.
- Photosynthesis: Food-making process in green plants.
- Transpiration: Loss of water vapour from plants.
- Stomata: Tiny pores on leaves that help in gaseous exchange and transpiration.
Plant Tissues
| Tissue | Main function |
|---|---|
| Meristematic tissue | Growth by cell division |
| Parenchyma | Storage and support |
| Collenchyma | Flexible support |
| Sclerenchyma | Mechanical strength |
| Xylem | Water conduction |
| Phloem | Food conduction |
Photosynthesis
Green plants use carbon dioxide and water to prepare glucose in the presence of sunlight and chlorophyll. Oxygen is released as a by-product.
Balanced Equation
Two phases:
- Light reaction (in grana of chloroplast): chlorophyll absorbs light, water is split (photolysis) releasing O₂, and ATP + NADPH are formed.
- Dark reaction / Calvin cycle (in stroma): ATP and NADPH are used to fix CO₂ into glucose. It does not need light directly.
Factors affecting the rate: light intensity, CO₂ concentration, temperature, water, and chlorophyll.
Transpiration
Transpiration helps in upward movement of water (transpiration pull), cooling the plant, and maintaining water balance. Excessive transpiration may cause wilting.
Types: stomatal (most water, through stomata), cuticular (through the cuticle), and lenticular (through lenticels). Guard cells open and close stomata by changing turgidity.
Xylem vs Phloem (deeper)
| Feature | Xylem | Phloem |
|---|---|---|
| Conducts | Water + minerals | Prepared food (sucrose) |
| Direction | Upward (roots → leaves) | Both ways (source → sink) |
| Process | Transpiration pull (passive) | Translocation (needs energy) |
| Living? | Mostly dead cells | Living cells |
Diagram Focus
- T.S. of dicot root
- T.S. of dicot stem
- Stomatal apparatus
- Xylem and phloem arrangement
Textbook Solution Strategy
1. Start answers with the definition. 2. Add function of the tissue or process. 3. For anatomy questions, draw and label the diagram clearly. 4. For physiology questions, mention inputs, process, and output. 5. End with importance or application.
Important Questions
One Mark
- Define tissue.
- What is the function of xylem?
- Name the green pigment involved in photosynthesis.
Two Marks
- Differentiate between xylem and phloem.
- What are the functions of transpiration?
- Why are stomata important?
Five Marks
- Explain photosynthesis with equation.
- Describe the internal structure of a dicot stem.
- Explain plant tissues and their functions.
Common Mistakes
- Confusing xylem and phloem functions.
- Forgetting chlorophyll in photosynthesis answers.
- Drawing diagrams without labels.
- Writing transpiration as loss of liquid water instead of water vapour.
Revision Checklist
- Plant tissue functions revised
- Xylem vs phloem comparison memorised
- Photosynthesis equation written correctly
- Dicot root and stem diagrams practised
- Transpiration importance revised