Warburg effect has not been observed in

Options

A. Maize
B. Sugarcane
C. Sorghum
D. All of these

Answer

### Step-by-Step Solution:

1. **Understanding the Warburg Effect**: The Warburg effect refers to the phenomenon where the rate of photosynthesis decreases under high oxygen concentration. This is primarily due to the competition between oxygen and carbon dioxide for the enzyme RuBisCO, leading to a process called photorespiration.

2. **Conditions Leading to the Warburg Effect**: The Warburg effect occurs when:
- There is a **high concentration of oxygen**.
- There is a **low concentration of carbon dioxide**.
In such conditions, plants tend to undergo photorespiration instead of photosynthesis.

3. **Identifying Plant Types**:
- **C3 Plants**: These plants are more susceptible to the Warburg effect because they do not have mechanisms to concentrate CO2, leading to higher rates of photorespiration under high oxygen conditions.
- **C4 Plants**: These plants have adaptations that allow them to maintain higher concentrations of CO2 and lower concentrations of O2 in their leaf tissues, thereby minimizing photorespiration.

4. **Examples of C4 Plants**: Common examples of C4 plants include:
- **Maize**
- **Sugarcane**
- **Sorghum**
These plants effectively avoid the Warburg effect due to their unique photosynthetic pathways.

5. **Conclusion**: Since the Warburg effect is not observed in C4 plants due to their ability to maintain CO2 and O2 concentrations, the answer to the question "Warburg effect has not been observed in" is **all of the above** (referring to maize, sugarcane, and sorghum).

### Final Answer:
The Warburg effect has not been observed in **C4 plants** such as maize, sugarcane, and sorghum.

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