What is the water potential of the potato cells?

Figure 1.1 A potato cell is placed in pure water. Initially the water potential outside the cell is 0 and is higher than the water potential inside the cell (-‐3). Under these conditions there will be a net movement of water into the cell.

How do you find the water potential of a potato cell?

Water potential (Ψ) is actually determined by taking into account two factors – osmotic (or solute) potential (ΨS) and pressure potential (ΨP). The formula for calculating water potential is Ψ = ΨS + ΨP.

Would the water potential of the potato cells change?

If the potato is allowed to dehydrate by sitting out in the open air the water potential would decrease (be more negative) because the concentration of solutes within the cells would increase as potato cells dehydrate. Therefore, the osmotic pressure and water potential both decrease.

What happens to potato cells in pure water?

The first potato slice is placed in distilled water, which is a high concentration of almost pure water, definitely higher than that which the potato’s cells contain. The water will diffuse into the cells of the potato, causing them to swell; the cells may be characterized as being “turgid”, or swollen.

What is the water potential of pure water?

The water potential of pure water is zero; aqueous solutions of increasing solute concentration have increasingly negative values. Water tends to move from areas of high water potential (more water, close to 0 value) to areas of low (less water, more solute, neg #’s) water potential.

Why does the mass of a potato increase in water?

The water passes through the potato cell membrane (a partially permeable membrane) into the potato, making it swell and increase in mass.

What are the factors that affect water potential?

Water potential is affected by factors such as pressure, gravity, and matric potentials….If a plant cell increases the cytoplasmic solute concentration:

  • Ψs will decline.
  • Ψtotal will decline.
  • the Δ between the cell and the surrounding tissue will decline.
  • water will move into the cell by osmosis.
  • Ψp will increase.

What is a higher water potential?

Water moves from areas of where water potential is higher (or less negative), to areas where it is lower (or more negative), and we refer to this movement as osmosis. Water potential is what allows water to get into plant roots when there is more solute within the root cells than the water in the soil.

What is leaf water potential?

Leaf water potential (LWP) indicates the whole plant water status, and maintenance of high LWP is found to be associated with dehydration avoidance mechanisms. Under relatively mild stress, delayed leaf rolling may be associated with sustained plant growth and production.

How is the water potential of a potato determined?

A plant cell, unlike an animal will not burst when water moves into a cell, it becomes turgid. This is because the cellulose cell wall prevents it from bursting. To find the water potential of a potato I will be placing fixed volumes of potato, with the same surface area, into different concentrations of sucrose solutions.

Why does water leave the potato cell when it reaches equilibrium?

Here, the water potential is lower than that of potato cell which has high water potential and low solute concentration. Therefore water will leave the potato cell to reach equilibrium with the sucrose solution. Hence, as water leaves the mass of the potato lowers.

How does osmosis affect the mass of a potato?

When the sucrose solution has a high concentration and a low water potential (lower than that of the potato), water will diffuse out of the potato into the sucrose solution and the mass of the potato will decrease.

What is the solute potential of potato tuber cells?

Using the trendline in figure 1 and figure 2, the solute potential of potato tuber cells was calculated as approximately -450kPa. A potato cylinder placed in a solution of this solute potential should not change in mass. The concentration of the sucrose solution in which no mass change of the potato cylinder would occur is 0.17mol dm-3.

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