Miss Angler's Biology Class: Transpiration
Overview
- Transpiration: Water loss through stomata (small openings) in plants.
- Important to understand plant tissues and structures for a comprehensive grasp of transpiration.
Structure and Function of Stomata
- Stomata: Pore-like openings on the underside of leaves.
- Guard Cells: Jelly bean-shaped cells controlling opening/closing of stomata.
- Vacuole: Inflation/deflation affects stoma opening.
- Unique Features: Contains chloroplasts to provide energy.
- Surrounded by thin epidermal cells without chloroplasts.
Plant Structures Involved in Transpiration
- Cuticle: Waxy layer preventing water loss.
- Epidermis: Protective outer layer, one cell thick.
- Palisade Mesophyll: Site of most photosynthesis.
- Vein: Consists of xylem and phloem, crucial for water transport.
- Spongy Mesophyll: Contains intercellular air spaces, significant for transpiration.
Water Movement Through Plants
- Water travels from roots through the stem, exiting via leaves.
- Path of Water: Xylem → Spongy Mesophyll → Intercellular Air Spaces → Stomata → Atmosphere.
Transpiration Processes
- Diffusion and Osmosis: Movement from high to low concentration.
- Evaporation: Water turns into vapor in air spaces, exits through stomata.
Measuring Transpiration
- Potometer: Device used to measure transpiration.
- Setup Precautions: Fresh twig, cut underwater, cut at an angle, use vaseline to avoid leaks.
- Function: Water movement observed through air bubble displacement, allowing calculation of transpiration rate.
Factors Affecting Transpiration Rate
- Wind: Increases transpiration by maintaining a low concentration gradient outside stomata.
- Humidity: Decreases transpiration by reducing concentration gradient.
- Temperature: Increases transpiration by accelerating evaporation.
- Light Intensity: Increases transpiration by increasing photosynthesis and temperature.
Terminology Recap
- Xylem: Water transport tissue.
- Diffusion/Osmosis: Movement process from high to low concentration, specific to water in osmosis.
- Spongy Mesophyll: Site of major transpiration activities.
- Stomata: Gateway for water and gases.
- Potometer: Instrument for measuring transpiration.
Study Tips: Use flashcards or mind maps with these terms and concepts for effective learning.