And Plant Resource Acquisition and Transport Flashcards
____ drives the transport of water and minerals from roots to shoots via the xylem.
Transpiration
How do water and minerals get into the root cells in the first place?
Water and minerals in the soil are absorbed through the roots
How do water and minerals get into the xylem
Roots
What is xylem sap? Is it mainly pushed up or down from the roots?
Water and dissolved minerals in the xylem. Mainly pushed from roots to shoots
What is transpiration?
loss of water through the leaves
What is root pressure and how does it develop?
Build up in pressure in roots. Develops as more and more water is taken in by the roots. Can only push water about 2 meters, which is why transpiration is necessary
What is guttation and why does it happen?
It is the exudation of water droplets that can be seen in the morning on the tips or edges of leaves. More water is entered in the leaves than is transpired
Why isn’t root pressure sufficient for getting xylem to the top?
It can only push it up a few meters at most because it is too weak to overcome the gravitational force of the water
What is the Cohesion-Tension hypothesis? Why is it a pulling process?
Transpiration provides the pull for the ascent of xylem sap, and the cohesion of water molecules transmits this pull from roots to shoots
What is cohesion and adhesion?
Cohesion: two like things being attracted to each other.
Adhesion: two different things being attracted to each other
How does loss of water vapor from the leaf translate into a pulling force for upward movement of water through a plant?
The negative pressure potential that causes water to move up through the xylem develops at the surface of mesophyll cell walls in the leaf
What is translocation?
Transport of products of photosynthesis
What are sieve tube elements, sieve tubes and companion cells?
Sieve tube elements: lack a nucleus, ribosomes, distinct vacuole. reduction in cell contents allows nutrients to pass easier.
Sieve tube: consists of chains of cells called sieve tube elements
Companion Cells: nonconducting cell which is connected to the sieve tube element
What is phloem sap?
Aqueous solution that flows through sieve tubes. Can flow either direction. Moves from sugar production sites or storage to sites of sugar use or storage
What is the direction of translocation compared to the direction of water/mineral transport?
Water and mineral transport is from soil to roots to leaves. They are directional opposites. Transporting sugars from leaves to lower parts of the plant
