In the DNA of an animal percentage of Adenine is 30 then percentage of Guanine will be -

Options

A. 40
B. 30
C. 20
D. 70

Answer

To determine the percentage of Guanine in the DNA of an animal where the percentage of Adenine is given as 30%, we can follow these steps:

### Step 1: Understand the Base Pairing Rules
In DNA, the base pairing rules dictate that Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). This means that the percentage of Adenine will equal the percentage of Thymine.

### Step 2: Calculate the Percentage of Thymine
Since the percentage of Adenine is given as 30%, the percentage of Thymine will also be 30%.

- Percentage of Thymine (T) = Percentage of Adenine (A) = 30%

### Step 3: Calculate the Total Percentage of A and T
Now, we can calculate the total percentage of Adenine and Thymine combined:

- Total percentage of A and T = Percentage of Adenine + Percentage of Thymine
- Total percentage of A and T = 30% + 30% = 60%

### Step 4: Determine the Remaining Percentage for G and C
Since the total percentage of all four bases (A, T, G, C) must equal 100%, we can find the percentage of Guanine and Cytosine combined:

- Remaining percentage for G and C = 100% - Total percentage of A and T
- Remaining percentage for G and C = 100% - 60% = 40%

### Step 5: Calculate the Percentage of Guanine and Cytosine
According to the base pairing rules, Guanine and Cytosine will also be present in equal amounts. Therefore, we can divide the remaining percentage equally between Guanine and Cytosine:

- Percentage of Guanine (G) = Remaining percentage for G and C / 2
- Percentage of Guanine (G) = 40% / 2 = 20%

### Conclusion
Thus, the percentage of Guanine in the DNA of the animal is 20%.

### Final Answer:
The percentage of Guanine will be 20%.

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