Transpiration Flashcards
What is the function of the upper epidermis?
It’s a waxy waterproof layer that reduces water loss
What is the function of each mesophyll layer?
Palisade mesophyll - absorbs light for photosynthesising contains many chloroplasts
Spongy mesophyll - has air spaces which allow gases to reach leaf cells for photosynthesis
What is the function of the lower epidermis?
Contains pores called stomata which allows gases to diffuse in and out of the leaf
What is the function of the stomata?
Allows water vapour to leave and is the site of gas exchange
What is the function of the guard cells?
Controls the opening and the closing of the stomata
What to water and minerals enter the plant through?
Specialised cells called root hair cells
What process does water move by?
Osmosis
Explain how water and minerals are transported in plants
The water moves via osmosis from the soil into the root hair cells. The water and minerals are then transported from the roots to other parts of the plant.
What vessels are water and minerals transported?
Xylem vessels
Do xylem cells have cell contents?
No
What tough, waterproof substance is xylem vessels lined with?
Lignin
What does lignin enable the xylem cells to do?
Withstand the pressure changes as water moves through the plant
How is lignin arranged and what does it provide to the cells?
Lignin is arranged as rings/spirals and provided support to the cells
When xylem cells are laid end to end, what do they form?
A rigid pipe
What is produced in the leaves during photosynthesis?
Sugar
The sugar is then transported up and down the plant in what?
Living phloem cells
What 2 thing do phloem cells have?
Sleve plates and associated companion cells
What do companion cells provide for sleve cells?
Energy
What do sleve played have and what can be transported?
They have pores which sugar can be transported
Define transpiration
The process of water moving through a plant and its evaporation through the stomata
Explain the 3 stages of transpiration
- Water enters into plant through root hair cells by the process of osmosis.
- Xylem vessels transport water into the leaves.
- Water evaporates from the leaf through stomata.
What internal factor affects the rate of transpiration?
The surface area
Smaller leaves contain less what causing a decrease in the rate of transpiration?
Less stomata
List 3 external factors that can also affect the rate of transpiration
- Increase in temperature
- Increase in wind speed
- decrease in humidity
What term is used to describe guard cells when the plant has plenty of water and why is this?
Turgid so that water can leave the plant