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 answer the question of how diatoms differ from algae, we will analyze each option provided in the question step by step.

### Step 1: Analyze the Mode of Nutrition
- **Diatoms** and **algae** both primarily exhibit an autotrophic mode of nutrition, meaning they can produce their own food through photosynthesis. Therefore, this option is incorrect as a distinguishing factor.

**Hint:** Consider how organisms obtain their energy and nutrients when comparing them.

### Step 2: Examine the Presence of Sculptured Plates
- The presence of intricately sculptured plates is a characteristic feature of **diatoms**. Diatoms have a unique silica cell wall that forms two halves, resembling a petri dish. This option is a distinguishing feature of diatoms.

**Hint:** Look for structural differences in the cell walls of the organisms when comparing them.

### Step 3: Assess the Presence of Bivalve Siliceous Frustules
- Diatoms are specifically characterized by their **bivalve siliceous frustules**. This means they have a silica-based cell wall that is unique to them, making this option a correct distinguishing feature of diatoms.

**Hint:** Think about the composition of the cell walls and how they contribute to the classification of organisms.

### Step 4: Evaluate Habitat and Flagellar Organization
- Both **diatoms** and **algae** are primarily aquatic organisms, meaning they inhabit water environments. Additionally, their flagellar organization is similar, as both groups can have flagella for movement. Thus, this option does not serve as a distinguishing factor.

**Hint:** Consider the living environments and structural similarities when determining differences.

### Conclusion:
From the analysis, the correct distinguishing features of diatoms compared to algae are the presence of sculptured plates and the presence of bivalve siliceous frustules. The mode of nutrition and habitat do not differentiate them.

### Final Answer:
Diatoms differ from algae primarily in the presence of bivalve siliceous frustules and sculptured plates, while they share similarities in mode of nutrition and habitat.