Transport in plants Flashcards
What is the primary function of the transport system in plants?
To enable leaves to receive water for photosynthesis and mineral ions for conversion into useful substances
What are the two main types of vascular tissue in plants?
- Xylem
- Phloem
Describe the structure of xylem.
- Made up of thick-walled dead cells
- No cytoplasm, completely hollow
- Arranged end to end
- Cell wall contains lignin, which is waterproof
What does xylem transport?
Water and mineral ions from the roots to the leaves
What ions are essential for making amino acids and proteins?
- Nitrate ions
- Magnesium ions
How is sucrose formed from photosynthesis?
The sugar made in photosynthesis is converted to sucrose
What does phloem transport?
- Sucrose
- Amino acids
What is translocation in plants?
The movement of sucrose and amino acids around the plant that requires energy
What is the main site of water absorption in plants?
Root hairs
How does water enter root hair cells?
By osmosis from the surrounding soil water
What is transpiration?
The evaporation of water from the surface of a plant
What causes water to be pulled up the xylem in a continuous flow?
Transpiration stream
List the functions of the transpiration stream.
- Carry mineral ions to leaves
- Keep turgor pressure high in leaf cells
- Evaporate cooling for leaves
- Supply water for photosynthesis
How does temperature affect transpiration?
Transpiration increases as temperature increases
What effect does humidity have on transpiration?
Transpiration slows down in humid air and increases in dry air
How does wind speed influence transpiration?
Transpiration increases as wind speed increases
What is the role of guard cells in stomatal opening?
They control the opening and closing of stomata
What happens to guard cells in light?
They photosynthesize, become turgid, and open the stomata
What is the purpose of a potometer?
To estimate transpiration rates
Fill in the blank: The sieve tube in phloem is controlled and supported by _______.
[companion cells]
What causes the high pressure in the sieve tube of phloem?
Water moves into the sieve tube by osmosis from nearby cells due to low water potential
What happens to stomata at night?
They close as sugar concentration falls and water potential increases in guard cells
What happens when a plant experiences water shortage?
Guard cells become flaccid, stomata close, and transpiration is reduced
Describe the structure of phloem.
- Composed of living cells
- Tubes formed by cells arranged end to end
- Cell walls made of cellulose
