Which of the following statement is incorrect ?

Options

A. Backbone of DNA is formed by sugar-phosphate-sugar chain
B. Nucleic acids are present in acid soluble fraction of any living tissue
C. DNA and RNA function as genetic material
D. There are three hydrogen bonds between G and C in DNA molecule

Answer

To determine which statement is incorrect, let's analyze each option step by step.

### Step 1: Analyze the first statement
**Statement:** "The backbone of DNA is formed by sugar phosphate sugar chain."

**Analysis:**
The backbone of DNA is indeed formed by alternating sugar (deoxyribose) and phosphate groups. Each nucleotide consists of a phosphate group, a sugar molecule, and a nitrogenous base. The sugar and phosphate form the backbone, while the nitrogenous bases extend from this backbone. Therefore, this statement is **correct**.

### Step 2: Analyze the second statement
**Statement:** "Nucleic acids are present in the acid-soluble fraction of any living tissue."

**Analysis:**
Nucleic acids (DNA and RNA) are high molecular weight macromolecules. They are typically found in the acid-insoluble fraction of living tissues, as they do not dissolve in acidic conditions. Instead, low molecular weight compounds are found in the acid-soluble fraction. Therefore, this statement is **incorrect**.

### Step 3: Analyze the third statement
**Statement:** "DNA and RNA function as genetic material."

**Analysis:**
DNA is the primary genetic material in most organisms, including humans. RNA can also serve as genetic material in certain viruses (e.g., retroviruses). Thus, this statement is **correct**.

### Step 4: Analyze the fourth statement
**Statement:** "There are three hydrogen bonds between guanine and cytosine in a DNA molecule."

**Analysis:**
According to Chargaff's rules, guanine (G) pairs with cytosine (C) through three hydrogen bonds, while adenine (A) pairs with thymine (T) through two hydrogen bonds. Therefore, this statement is **correct**.

### Conclusion
After analyzing all the statements, the **incorrect statement** is the second one: "Nucleic acids are present in the acid-soluble fraction of any living tissue."

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