Which of these statements is not true about DNA?

Options

A. It is the genetic material of the cell
B. Adenine pairs with thymine and guanine pairs with cytosine
C. It contains the sugar ribose
D. Sugar and phosphate groups form the backbone of the molecule

Explanation

To determine which statement is not true about DNA, we can analyze each provided statement step by step.

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA (Deoxyribonucleic Acid) is a thread-like structure located in the nucleus of the cell. It is composed of nucleotides, which include a sugar, phosphate group, and nitrogenous bases.

2. **Evaluating the First Statement**:
- The first statement claims that DNA is the genetic material of the cell.
- **Analysis**: This is true because DNA contains genes that encode the genetic information necessary for the development and functioning of living organisms.

3. **Evaluating the Second Statement**:
- The second statement mentions that adenine pairs with thymine and guanine pairs with cytosine.
- **Analysis**: This is also true. In DNA, adenine (A) pairs with thymine (T) through two hydrogen bonds, and guanine (G) pairs with cytosine (C) through three hydrogen bonds.

4. **Evaluating the Third Statement**:
- The third statement states that DNA contains the sugar ribose.
- **Analysis**: This is incorrect. DNA contains deoxyribose sugar, not ribose. Ribose is found in RNA (Ribonucleic Acid).

5. **Evaluating the Fourth Statement**:
- The fourth statement claims that sugar and phosphate groups form the backbone of the molecule.
- **Analysis**: This is true. The backbone of the DNA structure is formed by alternating sugar (deoxyribose) and phosphate groups.

6. **Conclusion**:
- Based on the evaluations, the statement that is not true about DNA is the third statement: "It contains the sugar ribose."

### Final Answer:
The statement that is not true about DNA is: **"It contains the sugar ribose."**

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