Arrange the following in correct ascending order based on their number
I. DNA molecules in anaphase chromosome
II. Kinetochores at a centromere of a metaphase chromosome
III. Types of histone in a nucleosomes core
IV. Number of histones in a nucleosomes core

Options

A. I, II, III, IV
B. IV, III, II, I
C. I, IV, III, II
D. I, III, IV, II

Answer

To arrange the given items in correct ascending order based on their number, we will analyze each item step by step.

### Step-by-Step Solution:

1. **DNA molecules in anaphase chromosome (I)**:
- During anaphase, each chromosome is split into two sister chromatids, and these chromatids are pulled to opposite poles of the cell.
- If we consider a typical diploid organism with 4 chromosomes, there would be a total of 8 DNA molecules (4 chromosomes × 2 chromatids each).
- **Total = 8 DNA molecules.**

2. **Kinetochores at a centromere of a metaphase chromosome (II)**:
- Each metaphase chromosome has two kinetochores, one at each sister chromatid.
- Therefore, for one metaphase chromosome, the total number of kinetochores is 2.
- **Total = 2 kinetochores.**

3. **Types of histone in a nucleosome core (III)**:
- The nucleosome core is made up of five different types of histones: H1, H2A, H2B, H3, and H4.
- **Total = 5 types of histones.**

4. **Number of histones in a nucleosome core (IV)**:
- A nucleosome core consists of an octamer of histones, which includes 2 copies each of H2A, H2B, H3, and H4 (totaling 8 histones).
- Additionally, there is one H1 histone associated with the nucleosome, bringing the total to 9.
- **Total = 9 histones.**

### Summary of Totals:
- I. DNA molecules in anaphase chromosome = 8
- II. Kinetochores at a centromere of a metaphase chromosome = 2
- III. Types of histone in a nucleosome core = 5
- IV. Number of histones in a nucleosome core = 9

### Ascending Order:
Now, we can arrange these totals in ascending order:
1. Kinetochores at a centromere of a metaphase chromosome (II) = 2
2. Types of histone in a nucleosome core (III) = 5
3. DNA molecules in anaphase chromosome (I) = 8
4. Number of histones in a nucleosome core (IV) = 9

### Final Answer:
The correct ascending order based on their number is:
II < III < I < IV