Problem 89 - Objective Biology for NEET

Question

The following features belongs to A. Mycelium septate and branched. B. Some members are saprophytes or parasites. C. Reproduce only by conidia. (a) Ascomycetes (b) Deuteromycetes (c) Basidiomycetes (d) Phycomycetes

Step-by-Step Solution

Answer

The type of fungus that matches all the given features is (b) Deuteromycetes.

Step 1: Identify Type of Fungus with Septate and Branched Mycelium

Mycelium septate is a feature found in Ascomycetes, Deuteromycetes, and Basidiomycetes. It is not present in Phycomycetes. So, options (a), (b) and (c) remain.

Step 2: Identify Fungus with Saprophytic or Parasitic Members

Ascomycetes, Deuteromycetes, Basidiomycetes and Phycomycetes can all be saprophytes or parasites. Thus, this feature doesn't help us eliminate any of the remaining options.

Step 3: Identify Type of Fungus that Reproduces Only by Conidia

Only Deuteromycetes reproduce only by conidia. Ascomycetes, Basidiomycetes, and Phycomycetes utilize other methods of reproduction as well. So, our final choice is Deuteromycetes.

Key Concepts

Fungal classification

Fungal classification can sometimes seem complex because fungi are a diverse group of organisms. Yet, understanding how fungi are classified helps us understand their roles in nature and how they function biologically. Here’s a simple breakdown.

Fungi are traditionally categorized into several major groups based on their characteristics, ways of reproduction, and life cycle stages.

• **Ascomycetes**: Also known as sac fungi, they reproduce sexually through the formation of spores in a sac-like structure called an ascus.
• **Basidiomycetes**: Known for producing spore-bearing structures called basidia; many mushrooms belong to this group.
• **Phycomycetes**: Also referred to as lower fungi, they usually have non-septate mycelium and often reproduce both sexually and asexually.
• **Deuteromycetes**: Often called fungi imperfecti, they are unique because their sexual form of reproduction has never been observed. Instead, they reproduce asexually, especially by conidia.

Understanding these categories helps in identifying various fungi and predicting their ecological roles and impacts.

Mycelium

Mycelium is a vital part of a fungus, often called its "body." The mycelium is a network of thread-like structures known as hyphae. These hyphae spread out and form what can resemble a web throughout the substrate where the fungus is growing, whether it's soil, wood, or any organic material.

Mycelium can be categorized based on its structure:

• **Septate Mycelium**: This type of mycelium has hyphae that are divided into cells by cross-walls known as septa. This feature is common in groups like Ascomycetes, Basidiomycetes, and Deuteromycetes.
• **Non-Septate (Coenocytic) Mycelium**: Here, the hyphae form long continuous cells without septa, often seen in groups such as Phycomycetes.

The structure of the mycelium is crucial for the classification of fungi and understanding how they interact with their environment. It plays a critical role in the way fungi absorb nutrients and contribute to ecosystems, such as decomposing organic material.

Conidia

Conidia are asexual spores produced by fungi, and they serve as a primary method of reproduction for certain fungi. These spores are often formed at the tips or sides of specialized hyphae known as conidiophores.

Conidia can vary greatly in size, shape, and color.

• Reproductive Role: Conidia allow fungi to reproduce and spread rapidly in suitable conditions due to their ability to form without sexual reproduction.
• Diversity: Conidia are the sole form of reproduction in Deuteromycetes, but other fungi like Ascomycetes can use them as part of their asexual cycles.

In the ecosystem, conidia play a vital role as they aid in the dispersal and colonization of fungi in new environments. They are incredibly resilient and can survive harsh conditions, allowing fungi to thrive and maintain their ecological roles.