The AT/GC ratio in human beings is (where A=adenine, T=thymine, G=guanine, C=cytosine)

Options

A. `1.52`
B. `1.25`
C. `0.93`
D. 1

Answer

To find the AT/GC ratio in human beings, we need to understand the relationship between the nitrogenous bases in DNA.

### Step-by-Step Solution:

1. **Understand the Bases**: In DNA, the bases are adenine (A), thymine (T), guanine (G), and cytosine (C). The base pairing rules state that adenine pairs with thymine and guanine pairs with cytosine.

2. **Define the Ratio**: The AT/GC ratio is defined as the ratio of the amount of adenine and thymine (A + T) to the amount of guanine and cytosine (G + C).

3. **Collect Data**: In human beings, the approximate composition of these bases is known from various studies. The ratio of A + T to G + C is generally reported to be around 1.5.

4. **Calculate the Ratio**:
- If we let A + T = x and G + C = y, then the AT/GC ratio can be expressed as:
\[ \text{AT/GC ratio} = \frac{x}{y} \]
- Based on the known data for humans, we find that:
\[ \frac{A + T}{G + C} \approx 1.5 \]

5. **Select the Correct Option**: Given the options provided (1.5, 1.25, 0.93, and 1), we can conclude that the correct answer is 1.5.

### Final Answer:
The AT/GC ratio in human beings is **1.5**.

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