The structures that are formed by stacking of organized flattened membranous sacs in the chloroplasts are:

Options

A. Stroma lamellae
B. Stroma
C. Cristae
D. Grana

Answer

To answer the question, "The structures that are formed by stacking of organized flattened membranous sacs in the chloroplasts are:", we need to understand the components of chloroplasts and their functions. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Chloroplast Structure**:
- Chloroplasts are organelles found in plant cells that are responsible for photosynthesis. They have a double membrane structure, consisting of an outer membrane and an inner membrane.

2. **Identifying Key Components**:
- Inside the chloroplast, there are various structures, including the stroma (the fluid-filled space), thylakoids (flattened membranous sacs), and grana (stacks of thylakoids).

3. **Defining Thylakoids and Grana**:
- **Thylakoids**: These are the individual flattened membranous sacs where the light-dependent reactions of photosynthesis occur.
- **Grana**: When multiple thylakoids are stacked together, they form a structure called a granum (singular). The plural of granum is grana.

4. **Connecting Structures**:
- The thylakoids are interconnected by stroma lamellae, which help in the organization of the thylakoids into stacks (grana).

5. **Conclusion**:
- The question specifically asks for the structures formed by stacking of organized flattened membranous sacs. The correct answer is **grana**, which are made up of stacked thylakoids.

### Final Answer:
The structures that are formed by stacking of organized flattened membranous sacs in the chloroplasts are **grana**.

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