Which of the following is an incorrect statement about the possible endosymbiotic origin of chloroplasts and mitochondria?

Options

A. They are the appropriate size to be descendants of bacteria
B. They contain their own genome and produce all their own proteins
C. They contain circular DNA molecules not associated with histones
D. Their membranes have enzymes and transport systems that resemble those found in the plasma membranes of prokaryotes

Explanation

To determine which statement about the possible endosymbiotic origin of chloroplasts and mitochondria is incorrect, let's analyze the key concepts step by step.

### Step 1: Understand the Endosymbiotic Theory
The endosymbiotic theory suggests that chloroplasts and mitochondria originated from free-living prokaryotic organisms that were engulfed by ancestral eukaryotic cells. Over time, these engulfed organisms formed a symbiotic relationship with their host cells.

**Hint:** Recall the basic premise of the endosymbiotic theory and its implications for the evolution of organelles.

### Step 2: Identify the Functions of Chloroplasts and Mitochondria
- **Chloroplasts** are found in plant cells and are responsible for photosynthesis, converting light energy into chemical energy.
- **Mitochondria** are known as the powerhouse of the cell, generating ATP through cellular respiration.

**Hint:** Remember the specific functions of chloroplasts and mitochondria to understand their roles in the cell.

### Step 3: Analyze the Statements
We need to evaluate the statements regarding the endosymbiotic origin of chloroplasts and mitochondria. One of the statements claims that they "contain their own genome and produce all their own protein."

- While chloroplasts and mitochondria do have their own DNA, they do not produce all their own proteins independently. They rely on the nuclear genome of the host cell for many of their proteins.

**Hint:** Consider the relationship between the organelles and the host cell's nucleus in terms of protein synthesis.

### Step 4: Determine the Incorrect Statement
Given the analysis, the statement that "they contain their own genome and produce all their own protein" is incorrect. This is because, although they have their own DNA, they do not synthesize all proteins independently; many proteins are encoded by the nuclear genome and imported into the organelles.

**Hint:** Focus on the dependency of chloroplasts and mitochondria on the host cell for certain proteins to identify the incorrect statement.

### Conclusion
The incorrect statement about the possible endosymbiotic origin of chloroplasts and mitochondria is that they "contain their own genome and produce all their own protein."