Hello I have question for my Plant Physiology Biology 425 Class. Answer the foll

Question

Hello I have question for my Plant Physiology Biology 425 Class.

Answer the following as True or False:

the permanent wilting percentage (pwp) for most plants is -5 MPa

   water movement through a plant is driven by an active pumping system soil is a mixture of organic and inorganic molecules silt particles are larger than clay particles saturated soil has a very negative water potential the field capacity of sand, silt and clay is the same the amount of water held by sand, silt and clay at field capacity is the same

the permanent wilting percentage (pwp) for most plants is -5 MPa

all plants have the same PWP sand hold water more tightly than clay soil water potential is a function of osmotic potential and pressure (or matric potential which refers to the tension generated because of the adhesion of water to soil particles

Explanation / Answer

1. In plants water enter through roots and then transported upwards to all plant parts. The roots absorb water by pressure gradient and positive pressure enabling water to be absorbed by roots is called root pressure. The water absorbed by xylem moves upward by transpiration pull. Thus, water transportation in plants is acheived by this active pumping system. The given statement is true.

2. Soil is the medium constituting both the organic and inorganic elements. The organic matter in soil is contributed by dead and decaying animal and plant matter and occurs in the form of humus. The inorganic elements contain elements like carbon, nitrogen, phosphorus, calcium, magnesim and metals like zins, manganese, cadmium, chromium, gold, silver etc.. The given statement is true.

3. Silt particles are larger than clay particles. Clay particles have size of 0.002mm or below. Therefore, they form compact soils without gap for air. Silt particles have the size in the range of 0.002 to 0.05mm. The given statement is true.

4. Water potential is the water per unit volume relative to pure water under reference conditions. When soil is saturated with water the matrix potential is positive resulting filling of every pore of soil with water. This results in negative water potential in soils saturated with water. The given statement is true.

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