Plant Science & Biology
Photosynthesis, transpiration, root systems, mycorrhizae, chlorosis, nutrient deficiencies, and plant structures.
- Explain the processes of photosynthesis and transpiration in plants
- Describe root system types and the role of mycorrhizae
- Identify chlorosis and common nutrient deficiency symptoms
Leçon 1
Photosynthesis & Transpiration
Photosynthesis
Photosynthesis is the process by which plants convert light energy into chemical energy (sugar). Using sunlight, water, and carbon dioxide, plants produce glucose and release oxygen as a byproduct. The simplified equation is:
6CO2 + 6H2O + light energy = C6H12O6 + 6O2
Photosynthesis occurs primarily in the leaves, within specialized cell structures called chloroplasts that contain the green pigment chlorophyll. Chlorophyll absorbs red and blue light and reflects green light, which is why plants appear green.
Transpiration
Transpiration is the process of water loss through leaf stomata. Stomata are tiny pores on the underside of leaves that open and close to regulate gas exchange and water loss. When stomata open to take in CO2 for photosynthesis, water vapor escapes into the air.
Transpiration serves several functions:
- Drives the movement of water and dissolved nutrients from roots to leaves (the transpiration stream)
- Cools the plant through evaporation
- Maintains cell turgor (pressure) that keeps leaves firm
On hot, dry days, plants lose water through transpiration faster than roots can absorb it, causing wilting. Guard cells surrounding each stoma close the pore to reduce water loss during drought stress.
Exam Distinction
Photosynthesis = converting light to energy (sugar). Transpiration = water loss through leaf stomata. Do not confuse these two processes on the exam.
Photosynthesis is the process by which plants convert light to energy. Transpiration is water loss through leaf stomata. Both occur primarily in the leaves and are essential for plant survival.