Unit 3 - Transport in plants Flashcards
What is the vascular bundle made up of?
Xylem and phloem tissue
What are the products of photosynthesis?
Carbohydrates, proteins, lipids, nucleic acids
Why do plants need water? (5 reasons)
-to maintain turgidity of cells
-to transport nutrients around the plant
-to create an aqueous environment for reactions to occur
-to cool plants by evaporation
-for photosynthesis
How is water transported in the plant?
Via the xylem
In which part of the root is water taken up?
Root hairs
Why does the root have so many root hairs?
Increases the surface area able to take up water
What force is created by the bonds between water molecules?
Cohesion
What are force is created by the interaction between water molecules and the vessel holding the water?
Adhesion
What 3 processes are involved in the movement of water up the stem and through the leaf?
-root pressure
-capillarity (the tendency of a liquid in a capillary tube or absorbent material to rise or fall as a result of surface tension)
-cohesion-tension theory
Why is xylem a bundle of very narrow vessels rather than one wide vessel?
Greater heights of liquid are achieved in thinner tubes due to capillarity
-with a smaller tube there is a greater contact with the vessel wall compared with the volume of water in the centre
-so greater cohesive forces
Why is transpiration pull referred to as the Cohesion-tension theory?
-The cohesive force between water molecules pulls other molecules upwards as it is a continuous stream
-this puts pressure on the column of water
-this inward pressure is called tension
What is the function of lignin in Xylem?
It strengthen the walls to resist the forces generated by water moving up the stem
What is crucial about the cell walls of guard cells?
-the inner wall is thicker than the outer wall
Give 4 ways plants generally conserve water
-waxy cuticle
-stomata on underside of leaf
-closable stomata
-roots that grow down to the water in the soil
