Halophilic archaebacterium (Halobacterium salinarum) found in Great Salt Lake and Dead Sea cannot live in

Options

A. Less then 3 M `NaCl` concentration
B. Less than 5 M `NaCl` concentration
C. More than 4 M `NaCl concenteation
D. More than 3 M `NaCl` concentration.

Answer

### Step-by-Step Solution:

1. **Understanding Halophilic Archaebacteria**:
- Halophilic archaebacteria, such as *Halobacterium salinarum*, are organisms that thrive in highly saline environments. They are a specific type of archaebacteria that require high salt concentrations for their survival.

2. **Identifying Their Habitat**:
- These bacteria are commonly found in extreme saline environments like the Great Salt Lake and the Dead Sea. These locations have very high concentrations of sodium chloride (NaCl).

3. **Determining Minimum Salt Concentration**:
- Halophiles require a minimum concentration of NaCl to survive. Research indicates that they need at least 3 molar NaCl concentration to maintain their cellular functions and avoid osmotic stress.

4. **Analyzing the Options**:
- The question provides several options regarding the NaCl concentration in which *Halobacterium salinarum* cannot live:
- A) Less than 3 molar NaCl
- B) Less than 5 molar NaCl
- C) More than 4 molar NaCl
- D) More than 3 molar NaCl

5. **Evaluating Each Option**:
- **Option A (Less than 3 molar NaCl)**: Correct, as halophiles cannot survive in conditions below their minimum requirement of 3 molar NaCl.
- **Option B (Less than 5 molar NaCl)**: Incorrect, as they can survive in this range, provided it is above 3 molar.
- **Option C (More than 4 molar NaCl)**: Incorrect, as they can survive in this range too.
- **Option D (More than 3 molar NaCl)**: Incorrect, as they can survive in this range as well.

6. **Conclusion**:
- The correct answer is **A) Less than 3 molar NaCl**, as *Halobacterium salinarum* cannot survive in environments with salt concentrations below this threshold.