5 Written questions
5 Matching questions
- What is the pit membrane of the xylem and why is it important to water transfer?
- What are aquaporins and why are they important in plants?
- Explain how water in soil depends on soil type and structure
- What is the difference between diffusion and bulk flow?
- a this is a porous layer between the 2 pit pairs, made of 2 primary walls and a middle lamella. This membrane helps to prevent the spreading of gas bubbles within the xylem
- b water molecule attraction to a solid such as a cell wall or a glass tube
- c this includes things such as the particle diameter and the surface area per gram of soil, this affects the adhesion properties of water
- d they are integral membrane proteins that form water selective channels. They are faster then travel through the lipid bilayer and can alter the rate of flow but not the direction (still passive). They can also be gated to allow for active regulation of water
- e Diffusion, substances move down a concentration gradient, bulk flow moves down a pressure gradient
5 Multiple choice questions
- the measurement of free energy of water per unit of volume. (J/m^3)
- the random collisions and exchange of kinetic energy between water molecules driving a movement down concentration gradients
- pathway of water moving through a network of cells connected via the plasmodesmata going to the cortex driven by hydrostatic pressure
- the ease at which the water moves through the soil (remember spaces between soil particles)
- they are sites that could provide the action energy required for water to undergo change for liquid to gas. This can occur due to gas bubbles and is avoided in the xylem via piths in water transfer which are to small for most bubbles to pass.
5 True/False questions
What drives xylem water transport? → this is driven by pressure gradients
What is transpiration? → It is the formation of vapor/ gas bubble in flowing water which can rapidly collapse and produce shock waves provding energy to nucleating sites within the xylem.
What 3 properties of water create __ which is important for plants? → they are integral membrane proteins that form water selective channels. They are faster then travel through the lipid bilayer and can alter the rate of flow but not the direction (still passive). They can also be gated to allow for active regulation of water
Within the plant cells what affects tugor? → it is the relative expression of the free energy associated with water, it is the difference between the potential as a given state and the potential of substance at a standard state
Why doesn't water boil under the tension created during transport in the xylem? → molecular diffusion and bulk flow