Transport in Plants Flashcards
What is the function of a root hair cell?
Absorb minerals and water
What is the benefit of a palisade cell being located at the top of a leaf?
Lots of light absorption for photosynthesis
Compare a palisade cell with a root hair cell
Palisade cell has lots of chloroplasts for photosynthesis whereas a root hair cell has none. Root hair cell has a root hair projection to maximise surface area to volume ratio whereas a palisade cell does not. A palisade cell is located at the top of a leaf whereas a root hair cell is located underground. A palisade cells main function is to undergo photosynthesis whereas a root hair cells main function is to absorb water and mineral ions.
How do mineral ions enter a root hair cell
Active transport, from a low concentration of mineral ions in the soil, through the root hair cells partially permeable plasma membrane, to a high concentration of mineral ions in the root hair cell using a protein pump and ATP
How does water enter a root hair cell?
Osmosis has occurred. Water has moved from the hypotonic environment in the soil surrounding the root hair cell, through the partially permeable plasma membrane of the root hair cell, to the hypertonic cytosol of the root hair cell. The root hair cell becomes turgid.
What is the function of the permanent vacuole?
Stores cell sap (including water in root hair cell)
Why do plants need to absorb minerals?
Make other compounds in the plant.
Eg. phosphate ions to make nucleic acids and phospholipids
What is xylem tissue?
Continuous transport vessel of a plant with no sieve plates
Transports water and mineral ions in one direction, from roots to leaves
Made of elongated dead cells with no nucleus (make room for more water)
Cell walls strengthened with lignin which adheres to water
What is phloem tissue?
Ttransport vessel of a plant with sieve plates
Transports sucrose and other dissolved substances (eg. amino acids and hormones) in both directions of a plant, this is called translocation
Made living cells with no nucleus
What is translocation?
Movement of dissolved substances up and down a plant using the phloem.
What is a tissue made of?
Many cells
What is an organ made of?
Many tissues (which are made from many cells)
How are leaves adapted to ensure a short diffusion pathway?
Large surface area and thin
What is the function of the stomata?
Allow for gas exchange with the environment
Which cells are responsible for opening and closing the stomata?
Guard cells
What is transpiration?
The loss of water from the leaves of a plant through the stomata due to evaporation
How does transpiration help with water movement in a plant?
It creates a suction pressure which helps to draw water up the xylem from the roots
Why do stomata close at night?
Carbon dioxide is not required at night as there is no sunlight for photosynthesis to occur, so closing the stomata reduces water loss
What factors affect transpiration?
Humidity, temperature and wind velocity
How does increasing humidity affect the rate of transpiration?
As humidity increases, transpiration decreases due to reduction in the water diffusion gradient
How does increasing temperature affect transpiration?
As temperature increases, transpiration increases due to the increased kinetic energy of the water molecules
How does increasing wind speed affect transpiration?
As wind speed increases, transpiration increases due to maintenance of a steep water diffusion gradient
Why does the water that enters a plant not equal to the water that is lost by transpiration?
Some is used for other process like photosynthesis or hydrolysis reactions (eg. breakdown of ATP)
What is a potometer?
A device used to estimate transpiration rates
How is a potometer used to measure transpiration?
As water moves up through the plant, the air bubble moves along the scale giving a measure of water absorbed by the plant over time and hence transpiration rate.
