Consider the following statements :-
(i) Bacteria have rigid cell wall made up of cellulose
(ii) Bacteria do not reproduce by sexual reproduction.
(iii) Ammonia is oxidised to nitrite by the bacteria Nitrosomonas.
(iv) Viruses are obligate parasites, cannot be living without host cell.
Which of the statements are correct and incorrect ?

Options

A. i, ii correct and iii, iv incorrect
B. ii, iii correct and i, iv incorrect
C. iii, iv correct and i incorrect
D. iv correct and i, ii, iii, incorrect

Answer

To determine which statements are correct and incorrect, we will analyze each statement one by one.

### Step 1: Analyze Statement (i)
**Statement:** Bacteria have a rigid cell wall made up of cellulose.
**Analysis:** This statement is incorrect. Bacteria have a rigid cell wall made up of peptidoglycan, not cellulose. Cellulose is primarily found in the cell walls of plants.
**Conclusion:** Statement (i) is **incorrect**.

### Step 2: Analyze Statement (ii)
**Statement:** Bacteria do not reproduce by sexual reproduction.
**Analysis:** This statement is generally considered correct. Bacteria primarily reproduce asexually through binary fission. However, they can exchange genetic material through processes like conjugation, transformation, and transduction, which are not sexual reproduction in the traditional sense.
**Conclusion:** Statement (ii) is **correct**.

### Step 3: Analyze Statement (iii)
**Statement:** Ammonia is oxidized to nitrite by the bacteria Nitrosomonas.
**Analysis:** This statement is correct. Nitrosomonas is a type of bacteria that plays a key role in the nitrogen cycle by oxidizing ammonia (NH3) to nitrite (NO2-). This process is known as nitrification.
**Conclusion:** Statement (iii) is **correct**.

### Step 4: Analyze Statement (iv)
**Statement:** Viruses are obligate parasites, cannot be living without a host cell.
**Analysis:** This statement is correct. Viruses are considered obligate parasites because they cannot carry out metabolic processes or reproduce without infecting a host cell. Outside of a host, they are inactive and do not exhibit characteristics of living organisms.
**Conclusion:** Statement (iv) is **correct**.

### Summary of Findings
- Statement (i): Incorrect
- Statement (ii): Correct
- Statement (iii): Correct
- Statement (iv): Correct

### Final Conclusion
The correct statements are (ii), (iii), and (iv). The incorrect statement is (i).