On a warm summer day the transpiration pull is the main force that drives from root parenchyma into the root xylem. The table shows values of `Psi_(rho)`(pressure potential ) and `Psi_(s)`(solute potential) in root xylem and root parenchyma , in kPa. In which of the options (a-d) would tranpiration pull cause water to move from root parenchyma into the root xylem?

Options

A. `{:("Root parenchyma",,"Root xylem"),(Psi_(p) " " Psi_(s),,Psi_(p)" "Psi_(s)),("200 -190",,"-200 5"):}`
B. `{:("Root parenchyma",,"Root xylem"),(Psi_(p) " " Psi_(s),,Psi_(p)" "Psi_(s)),("-200 220",,"65 -5"):}`
C. `{:("Root parenchyma",,"Root xylem"),(Psi_(p) " " Psi_(s),,Psi_(p)" "Psi_(s)),("200 -220",,"65 -5"):}`
D. `{:("Root parenchyma",,"Root xylem"),(Psi_(p) " " Psi_(s),,Psi_(p)" "Psi_(s)),("200 -220",,"-65 -5"):}`

Answer

To determine in which option the transpiration pull would cause water to move from root parenchyma into the root xylem, we need to analyze the water potential values of both the root parenchyma and the root xylem for each option provided.

### Step-by-Step Solution:

1. **Understand Water Potential**:
Water potential (Ψ) is calculated using the formula:
\[ Ψ = Ψ_p + Ψ_s \]
where Ψ_p is the pressure potential and Ψ_s is the solute potential.

2. **Calculate Water Potential for Each Option**:
We will calculate the water potential for both root parenchyma and root xylem for each option (a-d).

- **Option A**:
- Root Parenchyma: Ψ_p = 10 kPa, Ψ_s = 0 kPa
\[ Ψ_{parenchyma} = 10 + 0 = 10 \text{ kPa} \]
- Root Xylem: Ψ_p = -195 kPa, Ψ_s = 0 kPa
\[ Ψ_{xylem} = -195 + 0 = -195 \text{ kPa} \]

- **Option B**:
- Root Parenchyma: Ψ_p = 20 kPa, Ψ_s = 0 kPa
\[ Ψ_{parenchyma} = 20 + 0 = 20 \text{ kPa} \]
- Root Xylem: Ψ_p = 60 kPa, Ψ_s = 0 kPa
\[ Ψ_{xylem} = 60 + 0 = 60 \text{ kPa} \]

- **Option C**:
- Root Parenchyma: Ψ_p = -20 kPa, Ψ_s = 0 kPa
\[ Ψ_{parenchyma} = -20 + 0 = -20 \text{ kPa} \]
- Root Xylem: Ψ_p = 60 kPa, Ψ_s = 0 kPa
\[ Ψ_{xylem} = 60 + 0 = 60 \text{ kPa} \]

- **Option D**:
- Root Parenchyma: Ψ_p = -20 kPa, Ψ_s = 0 kPa
\[ Ψ_{parenchyma} = -20 + 0 = -20 \text{ kPa} \]
- Root Xylem: Ψ_p = -70 kPa, Ψ_s = 0 kPa
\[ Ψ_{xylem} = -70 + 0 = -70 \text{ kPa} \]

3. **Compare Water Potentials**:
For water to move from root parenchyma to root xylem, the water potential of the parenchyma must be higher (less negative) than that of the xylem.

- **Option A**:
- Ψ_parenchyma = 10 kPa (higher)
- Ψ_xylem = -195 kPa (lower)
- **Water moves from parenchyma to xylem**.

- **Option B**:
- Ψ_parenchyma = 20 kPa (higher)
- Ψ_xylem = 60 kPa (lower)
- **Water does not move**.

- **Option C**:
- Ψ_parenchyma = -20 kPa (higher)
- Ψ_xylem = 60 kPa (lower)
- **Water does not move**.

- **Option D**:
- Ψ_parenchyma = -20 kPa (higher)
- Ψ_xylem = -70 kPa (lower)
- **Water moves from parenchyma to xylem**.

4. **Conclusion**:
The correct options where water moves from root parenchyma to root xylem are **Option A and Option D**.