Problem 49 - Objective Biology for NEET

Question

The arrangement of flagella in brown algae is (a) One and equally arranged (b) Two unequal and laterally arranged (c) Many flagella arranged anywhere on the body (d) Depends from organism to organism

Step-by-Step Solution

Answer

The correct arrangement of flagella in brown algae is (b) Two unequal and laterally arranged.

Step 1: Identify the biological concept

Determine which biology area this addresses.

Step 2: Recall relevant principles

Review key concepts.

Step 3: Apply knowledge

Use biological reasoning.

Step 4: State the answer

The answer is: The correct arrangement of flagella in brown algae is (b) Two unequal and laterally arranged.

Key Concepts

Types of Flagella

Flagella are fascinating whip-like structures that help many organisms move. They come in different types based on their number and arrangement, which affects how they function. In general, flagella can be classified into a few main types:

• Single Flagellum (Monotrichous) - This is when a cell has one flagellum.
• Tufted Flagella (Lophotrichous) - This is when a cell has a cluster of flagella at one or both ends.
• Amphitrichous - Here, flagella are present at both ends of the cell.
• Peritrichous - This means the cell has flagella distributed all over its surface.

In brown algae, we encounter a special type known as "laterally inserted flagella," which is an important feature of many of their swimming reproductive cells. Understanding these types helps explain how flagella contribute to different forms of locomotion.

Brown Algae Characteristics

Brown algae, or Phaeophyceae, are a large group of mostly marine algae. They are known for their distinctive brown color, which comes from the pigment fucoxanthin, masking the green of chlorophyll. These algae play a crucial role in marine environments and have several noteworthy characteristics:

• They can range in size from small tufts to large, complex structures like the giant kelp, which can reach lengths of over 45 meters.
• Brown algae are multicellular and exhibit a differentiated thallus that includes parts analogous to leaves, stems, and roots in land plants.
• Their cell walls contain alginic acid, which gives them a slimy feel and is ecologically important.

These characteristics enable them to perform various ecological roles, such as providing habitat and nourishment for marine life and contributing to the ocean's biomass.

Flagella Functions

The main function of flagella is to enable movement; however, they can perform other roles depending on the organism. In brown algae, flagella are particularly involved in the movement of gametes and spores. Here's how flagella function to support algae and other organisms:

• Motility - Flagella act like tiny propellers, allowing cells to swim through their environment. This is critical for reproduction and finding nutrients.
• Sensory Roles - In some organisms, flagella can pick up environmental cues, helping the cell respond to changes in its surroundings.
• Locomotion - Movement achieved through flagella helps organisms reach optimal conditions for growth and survival.

Understanding these functions is crucial for studying how organisms interact with their environments, reproduce, and ensure their survival.

Lateral Flagella Arrangement

The arrangement of flagella in organisms can vary widely, contributing to different locomotion strategies. In brown algae, the lateral flagella arrangement is a key characteristic for the movement of motile cells like sperm. This arrangement is specifically two unequal flagella attached on the side of the cell, a setup distinct from other patterns like peritrichous or amphitrichous.

In lateral flagella arrangement:

• The two flagella are of different lengths, where the longer one is smooth and the shorter one has hair-like structures.
• This allows for efficient swimming, as the different lengths and compositions optimize movement in water environments.
• This unique arrangement is adapted to the needs of the algae, helping them ensure effective reproduction by enabling their reproductive cells to move and find appropriate spots or partners.

Comprehending lateral flagella arrangement offers insights into the dynamics of brown algae's reproductive strategies and their adaptation to aquatic life.