Problem 82 - Objective Biology for NEET

Question

The following characteristics are of which of the given fungi? A. Mycelium branched and septate. B. Asexual spores are generally not found. C. Vegetative reproduction by fragmentation is common. D. Sex organs are absent but plasmogamy is by fusion of two somatic cells of different strains or genotype. (a) Phycomycetes (b) Basidiomycetes (c) Deuteromycetes (d) Ascomycetes

Step-by-Step Solution

Answer

The fungi that matches all the characteristics described in the question is Deuteromycetes.

Step 1: Identifying the Fungi Characteristics

Start by identifying the fungi that match each of the given characteristics. In this case, the characteristics pertain to the structure of the fungi (septate, branched Mycelium), the method of reproduction (absence of asexual spores, common vegetative reproduction by fragmentation), and the method of plasmogamy (fusion of two somatic cells of different genotype).

Step 2: Match Each Characteristic to the Fungi Types

Based on known characteristics of each fungi, match each characteristic to the fungi types. Make use of any biological resources or textbooks that provide information on the typical characteristics of Phycomycetes, Basidiomycetes, Deuteromycetes, and Ascomycetes.

Step 3: Select the Fungi with All Matched Characteristics

After matching all the characteristics, select the fungi type that matches all the characteristics described in the exercise. A fungi that does not match all the given characteristics must be eliminated.

Key Concepts

Mycelium Structure

Mycelium is an important part of fungi, acting as the vegetative structure. It comprises a network of thread-like structures known as hyphae. These hyphae can be either septate or non-septate.
Septate hyphae have partitions called septa between their cells, whereas non-septate hyphae are continuous and do not have these partitions.
The main functions of mycelium include:

• Absorbing nutrients from the surrounding environment for the fungal body.
• Providing structural support to the fungus.
• Participating in reproduction and growth by extending the network of hyphae.

One of the defining characteristics of fungi like Basidiomycetes and Ascomycetes is having a branching and septate mycelium.
Understanding mycelium is key to studying how fungi grow and thrive in various environmental conditions.

Fungal Reproduction

Fungi have a fascinating array of reproductive strategies. They can reproduce both sexually and asexually, depending on the species and environmental conditions.

• Asexual Reproduction: This usually involves the production of spores such as conidia or sporangiospores, which are dispersed into the environment to form new fungi. However, some fungi, like the ones described in the textbook problem, typically do not produce asexual spores and rely heavily on vegetative reproduction, often through fragmentation of the mycelium.
• Sexual Reproduction: This process includes stages like plasmogamy, karyogamy, and meiosis, leading to the fusion of genetic material from two different fungal cells.

Vegetative reproduction by fragmentation occurs when the mycelium breaks into pieces, each of which can grow into a new organism. Understanding these diverse reproductive methods is essential for exploring fungal life cycles and adaptation mechanisms.

Plasmogamy

Plasmogamy is a critical stage in the sexual reproduction process of fungi. It refers to the fusion of the cytoplasm from two distinct fungal cells. These cells usually come from different strains or genotypes.
During plasmogamy:

• The two fungal cells merge to form a cell with two separate nuclei, creating a stage known as a dikaryotic state.
• This stage might last for a while before progressing to karyogamy, where the nuclei themselves fuse.
• The dikaryotic phase is important for genetic diversity and adaptation.

In fungi such as Basidiomycetes, this process precedes the formation of complex fruiting bodies.
The absence of separate sex organs in these fungi means that plasmogamy occurs directly through the fusion of somatic cells, emphasizing the versatility and adaptability of fungal reproductive strategies.