Read the following four statements (i -iv)
(i) Every chromosome essentially has a primary constriction or the centromere.
(ii) During different stages of cell division, cells show structured chromosomes in place of the nucleus .
(iii) Nuclear pores are the passages through which movement of RNA and Protein takes place in one direction between the nucleus and cytoplasm.
(iv) Chromatin contains DNA, some basic proteins called histone adn RNA only .
How many of the above statement are correct

Options

A. Four
B. One
C. Two
D. Three

Answer

To determine how many of the statements (i - iv) are correct, let's analyze each statement one by one.

### Step 1: Analyze Statement (i)
**Statement (i)**: Every chromosome essentially has a primary constriction or the centromere.
- **Analysis**: This statement is true. Every chromosome has a centromere, which is the primary constriction point where the two sister chromatids are joined.

**Hint**: Recall the structure of chromosomes and the role of the centromere in chromosome organization.

### Step 2: Analyze Statement (ii)
**Statement (ii)**: During different stages of cell division, cells show structured chromosomes in place of the nucleus.
- **Analysis**: This statement is also true. During cell division, particularly in the phases of mitosis (prophase, metaphase, anaphase, and telophase), chromosomes become visible and structured, while the nucleus disassembles.

**Hint**: Think about the stages of cell division and how chromatin condenses to form visible chromosomes.

### Step 3: Analyze Statement (iii)
**Statement (iii)**: Nuclear pores are the passages through which movement of RNA and Protein takes place in one direction between the nucleus and cytoplasm.
- **Analysis**: This statement is true, but it is misleading because it implies movement in only one direction. RNA moves from the nucleus to the cytoplasm, while proteins can move in both directions (from cytoplasm to nucleus for various functions). However, the core idea about nuclear pores facilitating transport is correct.

**Hint**: Consider the functions of nuclear pores and the types of molecules that pass through them.

### Step 4: Analyze Statement (iv)
**Statement (iv)**: Chromatin contains DNA, some basic proteins called histone, and RNA only.
- **Analysis**: This statement is false. While chromatin does contain DNA and histone proteins, it also contains non-histone proteins and is not limited to RNA only.

**Hint**: Review the composition of chromatin and the types of proteins it includes.

### Conclusion
From the analysis:
- Statement (i) is correct.
- Statement (ii) is correct.
- Statement (iii) is correct in essence but could be misleading.
- Statement (iv) is incorrect.

Thus, **three statements (i, ii, and iii) are correct**.

### Final Answer
The number of correct statements is **3**.