All the given statement are true, except

Options

A. DNA is more stable the RNA because DNA contains 5 methyl uracil and deoxyribose
B. DNA replication is semi-conservation bidirectional and semi-discontinuous
C. Taylor proved semi-conservative replication of DNA by working on E. Coil bacteria
D. Klenow fragment' is a part of DNA polymerase.

Answer

To solve the question "All the given statements are true, except," we need to analyze each statement provided in the options and identify which one is incorrect.

### Step-by-Step Solution:

1. **Evaluate the First Statement:**
- The first statement claims that "DNA is more stable than RNA because 5-methyluracil and deoxyribose are present in DNA as a sugar."
- This statement is **true**. DNA is indeed more stable than RNA due to the presence of deoxyribose (which lacks an oxygen atom at the 2' position) and the absence of the hydroxyl group that is present in ribose, making DNA less susceptible to hydrolysis.

**Hint:** Consider the structural differences between DNA and RNA that contribute to their stability.

2. **Evaluate the Second Statement:**
- The second statement states that "DNA replication is Semi-Conservative, Bi-Directional, and Semi-Discontinuous."
- This statement is also **true**. DNA replication is semi-conservative because each new DNA molecule consists of one old strand and one new strand. It is bi-directional as replication occurs in both directions from the origin of replication, and it is semi-discontinuous because one strand (leading strand) is synthesized continuously while the other (lagging strand) is synthesized in short fragments (Okazaki fragments).

**Hint:** Recall the mechanisms of DNA replication and how the strands are synthesized.

3. **Evaluate the Third Statement:**
- The third statement mentions "Tailor-proof semi-conservative replication of DNA by working on E.coli bacteria."
- This statement is **incorrect**. The correct attribution for proving the semi-conservative nature of DNA replication is to Meselson and Stahl, not Taylor. Taylor's work was related to the replication of DNA in other contexts, but he did not prove the semi-conservative model.

**Hint:** Think about the historical experiments that demonstrated the semi-conservative replication of DNA.

4. **Evaluate the Fourth Statement:**
- The fourth statement says, "Chilofector fragment is a part of the DNA polymerase."
- This statement is **true**. The "Chilofector fragment" refers to a part of the DNA polymerase enzyme that is involved in the synthesis of DNA.

**Hint:** Consider the components and functions of DNA polymerase.

### Conclusion:
After evaluating all statements, the incorrect statement is the third one regarding Taylor's work on semi-conservative replication. Therefore, the answer to the question is the third statement.

### Final Answer:
The incorrect statement is: "Tailor-proof semi-conservative replication of DNA by working on E.coli bacteria."