TRANSPORT IN PLANTS Flashcards
What is the relationship between size and SA:Vol ratio in large plants?
Large plants have a small SA:Vol ratio
This impacts their need for specialized exchange surfaces and a transport medium.
What does each cell in a plant need?
Oxygen, water, sugars, and mineral ions
These are essential for cellular processes.
What is the respiration activity level in plants?
Plants aren’t very active (respiration is low)
This results in a low demand for oxygen.
How do plants meet their oxygen demand?
Plants can use diffusion
This is sufficient due to their low respiration rates.
What is the demand for water and sugars in plants?
The demand for water and sugars is still high
Despite low respiration, these resources are critical for plant functions.
Where do plants obtain water and mineral ions from?
Soil
Soil acts as a source for these essential elements.
What is produced by photosynthesis in plants?
Sugars
Photosynthesis is the process through which plants generate energy.
What does xylem consist of?
Xylem consists of vessels, fibres, and living parenchyma cells.
What is the function of vessels in xylem?
Vessels in xylem carry water and nutrients.
What is the role of fibres in xylem?
Fibres in xylem provide support to the plant.
What do living parenchyma cells do in xylem?
Living parenchyma cells act as packing tissue to separate and support the vessels.
What happens to parenchyma cells in xylem development?
Parenchyma cells in a column lose their end walls.
How do the walls of parenchyma cells change during xylem development?
Walls become strengthened with lignin.
What effect do impermeable and waterproof walls have on parenchyma cells?
They kill the cell.
What occurs to the protoplasm and end walls of parenchyma cells?
They decay to make unrestricted flow of water.
What is the role of lignin in plant cells?
Lignin strengthens the cell wall and prevents collapsing.
How does lignin help during water shortages?
Lignin keeps vessels open even at times when water may be in short supply.
What patterns can lignin thickening cause in the cell wall?
Lignin thickening causes patterns such as spiral, annular (rings), or reticulate (a network of broken rings), allowing flexibility.
What happens to plasmodesmata during lignification?
There is no lignification where plasmodesmata were present, leaving gaps in the cell wall that form bordered pits.
What is the function of bordered pits in plant cells?
Bordered pits allow movement of water between vessels.
What is the function of phloem?
Used to transport assimilates (mainly sucrose and amino acids) – the sucrose is dissolved to form sap.
What are sieve tube elements?
Components of phloem that facilitate the transport of sap.
What are companion cells?
Cells associated with sieve tube elements that support their function.
What are sieve tubes formed from?
Many individual sieve tube elements are aligned end to end to form long sieve tubes.
What do sieve tube elements contain?
They contain no nucleus and very little cytoplasm, leaving space for mass flow of sap to occur.
What are the perforated cross walls at the ends of sieve tube elements called?
They are called sieve plates.
What is the function of the perforations in the sieve plate?
Perforations in the sieve plate allow movement of the sap from one element to the next.
What are companion cells?
Small cells located between long sieve tubes, each with a large nucleus and dense cytoplasm.
What is the function of mitochondria in companion cells?
To produce ATP.
What metabolic processes do companion cells carry out?
They load assimilates actively into sieve tubes.
