In which class of algae, gametes are pyriform (pear-shaped) and bear two unequal laterally attached flagella?

Answer

To answer the question regarding the class of algae in which gametes are pyriform (pear-shaped) and bear two unequal laterally attached flagella, we can follow these steps:

### Step 1: Identify the Characteristics of Gametes
The question specifies two main characteristics of the gametes:
1. **Shape**: The gametes are described as pyriform (pear-shaped).
2. **Flagella**: There are two flagella that are unequal in size and are laterally attached.

### Step 2: Relate Characteristics to Algal Classes
Next, we need to determine which class of algae exhibits these specific characteristics. The two key features (pyriform shape and two unequal flagella) are essential for identifying the correct class.

### Step 3: Recall Algal Classes
There are several classes of algae, including:
- Green algae (Chlorophyceae)
- Red algae (Rhodophyceae)
- Brown algae (Phaeophyceae)

### Step 4: Match Characteristics to Brown Algae
Upon reviewing the characteristics:
- The class of brown algae (Phaeophyceae) is known to have gametes that are pyriform and possess two unequal flagella that are laterally attached.

### Step 5: Provide Examples
Examples of brown algae include:
- Laminaria
- Sargassum

### Conclusion
Thus, the class of algae in which gametes are pyriform and bear two unequal laterally attached flagella is **Brown Algae (Phaeophyceae)**.

---