Plant Transport Systems Flashcards
Why do multicellular organisms require transport systems?
Multicellular organisms have a small surface area to volume ratio therefore diffusion cannot occur fast enough to supply the raw materials to the whole cell. This means they have transport systems to carry the raw materials to the sites of their diffusion
Why do plants require transport systems for water?
To get the water from its roots into its leaves
Upper epidermis
A transparent layer which allows sunlight to pass through to the cells below
Palisade mesophyll
Closely packed cells which contain many chloroplasts - the site of photosynthesis
Spongy mesophyll
A layer that contains many air spaces where gases can diffuse into and out of cells. These cells also carry out photosynthesis
Guard cells
Two cells which control the opening of the stomata
Stomata
Pores on the underside of the leaf which allow gas exchange
Vein
Contains a vascular bundle composed of xylem and phloem which are two transport systems
Lower epidermis
Underside of the leaf
State the structures involved in transport of water in plants
Root hair cells, xylem
Describe the process of osmosis in plants.
-The water enters the plant through its roots which contain specialised cells called root hair cells. These cells have long extensions that increase the surface area of the cell allowing it to absorb more water and dissolved minerals
-Once inside inside the plant, water and minerals move up from through roots to the leaves in the stem in narrow tubes called xylem. Xylem are hollow tubes made of dead cells, they gave rings of lignin which stop the tubes closing under the pressure of water
Describe the structure and function of the xylem
Structure : hollow tubes made of dead cells, they have rings of lignin which top the tube closing under the pressure of the water
Function : transport water from the bottom to the top of the leaf
Name environmental factors which increase the rate of transpiration in plants
-Increased wind speed
-Increased temperature
-Increased surface area
-Increased humidity
Why do plants require a transport system for sugar?
To transport the sugar from the leaves to all cells
State the structures involved in the transport of sugar in plants
Phloem:
Composed of a sieve tube with sieve plates and companion cells
Transport all around the plant
Transports sugar
How do plants obtain water?
A plant obtains water through its roots, roots contain specialised cells called root hair cells.
These cells increase the surface are in which the plant can absorb water and nutrients from the soil
How do plants transport water and minerals?
Water is transported from the roots to other parts of the plant through dead Xylem vessels.
These dead xylem vessels (lignified) contains rings of lignin. This allows the xylem vessel to withstand the pressure changes as water moves throughout the plant
Describe the process of transpiration
Transpiration is the movement of water through the plant. Water evaporates from the stomata in the leaf, this causes pressure changes within the plant meaning more water is drawn through the plant from the roots back into the leaves
Describe how sugar is transported around the plant
Sugar is transported up and down the plant in living phloem tissue.
Phloem cells have sieve plates and associated companion cells to allow sugar to be transported to all parts of the plant
How is the rate of transpiration measured using a mass potometer?
Change in mass (g)
Divide by the number of minutes (experiment run for)
