Select the incorrect statement.

Options

A. Egg of ostrich is the largest isolated single cell
B. Ribosomes are organelle within the organelle
C. The Shape of the cells may vary with the function they perform
D. Genetic material is present in well defined nucleus in both prokaryotes and eukaryotes

Answer

To identify the incorrect statement from the options provided, we will analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement:** "The egg of the ostrich is the largest isolated single cell."
- **Explanation:** The ostrich egg is indeed the largest single cell known. It is a single cell before fertilization and is often cited as the largest isolated cell.
- **Conclusion:** This statement is **correct**.

### Step 2: Analyze the second statement
**Statement:** "Ribosomes are organelles within an organelle."
- **Explanation:** Ribosomes are indeed considered organelles. They are found within the mitochondria (which are organelles themselves) as well as in the cytoplasm of eukaryotic cells. The statement is somewhat misleading but can be interpreted as correct in the context of mitochondria.
- **Conclusion:** This statement is **correct**.

### Step 3: Analyze the third statement
**Statement:** "The shape of cells may vary from the function they perform."
- **Explanation:** This statement is true as well. Different cell types have different shapes that are adapted to their specific functions (e.g., nerve cells, muscle cells, etc.).
- **Conclusion:** This statement is **correct**.

### Step 4: Analyze the fourth statement
**Statement:** "Genetic material is present in a well-defined nucleus in both prokaryotes and eukaryotes."
- **Explanation:** This statement is **incorrect**. Prokaryotes do not have a well-defined nucleus; instead, their genetic material is located in a region called the nucleoid, which is not surrounded by a membrane. Eukaryotes, on the other hand, have a well-defined nucleus that contains their genetic material.
- **Conclusion:** This statement is **incorrect**.

### Final Answer
The incorrect statement is: **"Genetic material is present in a well-defined nucleus in both prokaryotes and eukaryotes."**

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