Problem 48 - Objective Biology for NEET

Question

Zoospores of brown algae are (a) Uniflagellate (b) Multiflagellate (c) Biflagellate (d) May be any of the above three

Step-by-Step Solution

Answer

The zoospores of brown algae are Biflagellate

Step 1: Understanding terms

Firstly, it's essential to have an understanding of the terms. Uniflagellate refers to an organism with a single flagellum, multiflagellate means having multiple flagella, and biflagellate refers to organisms with two flagella.

Step 2: Research on brown algae

Through research or previous knowledge, it can be established that brown algae (Phaeophyta) produce zoospores, which are motile asexual reproductive structures that are characteristic of certain kinds of algae and fungi. These zoospores are generally biflagellate, meaning they have two flagella.

Step 3: Choosing the correct answer

Upon researching the specifics of the zoospores in brown algae, it becomes clear that the correct answer is (c) Biflagellate as brown algal zoospores generally possess two flagella.

Key Concepts

Brown Algae

Brown algae belong to a group of important marine organisms known as Phaeophyta. These algae are predominantly found in cold oceanic waters and are known for their distinct brown coloration, which results from the presence of the pigment fucoxanthin alongside chlorophyll a and c. Brown algae can vary significantly in size and structure, ranging from small filamentous forms to large kelps that can grow up to 60 meters long.

These organisms play a vital role in marine ecosystems. They provide food and habitat for a variety of marine life. Additionally, brown algae are used in numerous industries, including food, cosmetics, and agriculture, due to their nutritional and supportive properties. Common examples of brown algae include kelps, rockweeds, and sargassum.

• Habitat: Primarily marine
• Pigment: Fucoxanthin
• Examples: Kelp, sargassum, rockweed

Biflagellate

The term "biflagellate" refers to cells or organisms that have two flagella. Flagella are whip-like appendages that enable movement in various single-celled and simple multicellular organisms. In the context of brown algae, biflagellate zoospores are a crucial aspect of their life cycle.

These motile spores, equipped with two flagella, are essential for the asexual reproduction of brown algae. One flagellum is oriented toward the rear and is typically smooth, while the other is forward and has fine hairs (mastigonemes). This dual flagella arrangement allows the zoospore to navigate through water effectively.

• Function: Movement and reproduction
• Structure: Two flagella (one smooth, one with mastigonemes)

Reproduction in Algae

Algae exhibit a variety of reproductive strategies, ranging from simple binary fission to more complex forms of both sexual and asexual reproduction. In brown algae, asexual reproduction often involves the formation of motile zoospores. These zoospores are released into the water and eventually settle to form new individuals.

Algae can also reproduce sexually, involving gametes that fuse to form a zygote. The specifics of sexual reproduction can differ widely among different groups of algae. In brown algae, the lifecycle includes an alternation of generations, where both a gametophyte (producing gametes) and a sporophyte (producing spores) generation appear.

• Asexual reproduction: Zoospores, fragmentation
• Sexual reproduction: Fusion of gametes
• Lifecycle: Alternation of generations