3.3- Transport in plants Flashcards
Why do plants need transport systems to move substances to and from individual cells quickly?
Plants are multicellular organisms and have a small surface area to volume ratio
They’re also relatively big with a high metabolic rate so direct diffusion would be too slow
What are the two types of tissue involved in the transport in plants?
Xylem tissue
Phloem tissue
What does xylem tissue transport?
Water and mineral ions in solution
It transports them from the roots to the leaves
What does phloem tissue mainly transport?
Sugars in solution
It transports them both up and down the plant
How the xylem and phloem positioned in the root of plants?
This xylem is in a centre x shape surrounded by phloem
This provides support for the group as it pushes through soil
How are the xylem and phloem positioned in stems?
The xylem and phloem are near the outside (phloem is nearer inside)
This provides a sort of scaffolding that reduces bending
How are xylem and phloem positioned in leaves?
Xylem and phloem make up a network of veins (phloem on bottom of leaf)
These veins support the thin leaf structure
A cross-section is said to be transverse. What does this mean?
The section has been cut through at a right angle to its length
A cross-section is said to be longitudinal. What does this mean?
The structure is cut through at a right angle to it’s width
How is xylem vessels adapted for transporting water and mineral ions?
Xylem vessels are long tube like elements formed from cells joined end-to-end
There are no end walls on cells, making an uninterrupted tube
The cells the dead so contain no cytoplasm
The cell walls are thickened with lignin and the amount increases as the cells get older
How is phloem tissue adapted for transporting solutes?
Sieve tube elements are joined end-to-end to form sieve tubes
Sieve tube elements have sieve plates which allows solutes to pass through
Sieve tube elements have no nucleus, a very thin layer of cytoplasm and few organelles which allows more transportation to occur
Companion cells carry out the living functions for both themselves and their sieve tube elements, this allows more space for transport in the phloem
