The best differentiation of mesophyll tissue into adaxial palisade tissue and abaxial spongy tissue is seen in plants with leaves that are

Options

A. Under water
B. Held vertical
C. Held horizontal
D. Succulent

Answer

To answer the question regarding the best differentiation of mesophyll tissue into adaxial palisade tissue and abaxial spongy tissue in plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Leaf Structure**:
- A leaf consists of two layers of epidermis: the upper epidermis and the lower epidermis.
- The upper epidermis is exposed to more sunlight, while the lower epidermis has more stomata for gas exchange.

**Hint**: Recall that the upper and lower epidermis serve different functions in a leaf.

2. **Identify Mesophyll Tissue**:
- The mesophyll tissue is located between the upper and lower epidermis and is responsible for photosynthesis.
- It is differentiated into two types: palisade tissue (adaxial) and spongy tissue (abaxial).

**Hint**: Remember that palisade tissue is more efficient in capturing sunlight due to its chloroplast content.

3. **Differentiate Between Palisade and Spongy Tissue**:
- Palisade tissue is located on the upper side (adaxial) and contains more chloroplasts, making it ideal for photosynthesis.
- Spongy tissue is located on the lower side (abaxial) and has fewer chloroplasts, as it receives less sunlight.

**Hint**: Think about how the position of these tissues relates to light exposure.

4. **Consider Leaf Orientation**:
- Leaves that are held horizontally (dorsi-ventral) maximize sunlight absorption on the upper surface, allowing for better differentiation of mesophyll tissue.
- In contrast, leaves held vertically or underwater would not have the same level of differentiation due to reduced sunlight exposure.

**Hint**: Visualize how the orientation of a leaf affects its ability to capture sunlight.

5. **Conclusion**:
- The best differentiation of mesophyll tissue into adaxial palisade tissue and abaxial spongy tissue is observed in leaves that are held horizontally.

**Final Answer**: The correct answer is "held horizontal."