Diatoms differ from the algae in :

Options

A. mode of nutrition
B. presence of sculptured plates
C. presence of bivalved siliceous frustules
D. habitat and flagella organisation

Answer

To solve the question "Diatoms differ from the algae in:", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Diatoms**: A group of microalgae belonging to the phylum Chrysophyta, characterized by their unique cell wall structure.
- **Algae**: A diverse group of photosynthetic organisms that can be found in various environments, typically containing chlorophyll.

2. **Identify Key Characteristics**:
- Diatoms are autotrophic, meaning they produce their own food through photosynthesis, similar to algae.
- Diatoms have a unique cell wall structure known as a frustule, which is made of hydrated silica.

3. **Compare Nutritional Modes**:
- Both diatoms and algae are autotrophs, so they do not differ in their mode of nutrition.

4. **Examine Structural Differences**:
- Diatoms possess a distinctive bivalve siliceous frustule, which is not found in typical algae. This structure is composed of two halves (theca) and is a significant distinguishing feature.

5. **Consider Other Factors**:
- Look at other characteristics such as habitat and flagella organization. Both diatoms and algae are primarily aquatic and share similar flagella structures, so these cannot be the distinguishing factors.

6. **Conclude the Main Difference**:
- The primary difference between diatoms and algae lies in the presence of the bivalve siliceous frustule in diatoms, which is not present in algae.

### Final Answer:
Diatoms differ from algae in the presence of bivalve siliceous frustules.

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