Problem 9 - Biology Concepts and Applications

Question

When a spore of a cellular slime mold germinates, it gives rise to a _____. a. free-living amoeboid b. fruiting body c. mycelium d. mycorrhiza

Step-by-Step Solution

Answer

A spore of a cellular slime mold germinates into a free-living amoeboid.

Step 1: Understand Cellular Slime Molds

Cellular slime molds are a type of protist known for their unique life cycle. They begin life as single-celled organisms and later can aggregate to form multicellular structures. An understanding of this life cycle is crucial to solving the exercise.

Step 2: Identify Key Transition in Life Cycle

When a spore germinates, it typically develops into a single-celled organism. In the case of cellular slime molds, the spore germinates into a free-living amoeboid, which is the primary motile feeding stage.

Step 3: Evaluate Options Given

Review the provided options: (a) free-living amoeboid, (b) fruiting body, (c) mycelium, (d) mycorrhiza. Given our understanding, the spore germinates into a free-living amoeboid cell, which later can contribute to forming a fruiting body.

Step 4: Confirm the Correct Answer

Based on the life cycle of cellular slime molds, the most direct product of a germinating spore is the free-living amoeboid. Therefore, the correct choice is (a).

Key Concepts

Life Cycle of Protists

Cellular slime molds are a fascinating group within the kingdom of protists, exhibiting a unique and complex life cycle. This life cycle is significant for their survival and reproduction. Protists in general, including cellular slime molds, go through various stages which allow them to adapt and thrive in diverse environments.

Typically, the life cycle of protists involves both asexual and sexual reproduction. Particularly for cellular slime molds, it starts with the germination of spores. When conditions are favorable, these spores germinate to form the primary cellular stage—free-living amoeboids. During this stage, they feed, grow, and multiply through binary fission.

• Spore Germination: The initial phase begins with the germination of spores into amoeboid cells.
• Growth Stage: These amoeboids consume bacteria and other microorganisms in their environment, proliferating as individual cells.
• Aggregation: When food is scarce, these cells aggregate to form a multicellular structure, preparing for the next stage.

Understanding this cycle highlights the protists' ability to shift between individual and collective phases, showcasing their adaptability.

Amoeboid Stage

The amoeboid stage is a crucial part of the life cycle of cellular slime molds. This stage is characterized by its motility and feeding capability. In this phase, the organisms demonstrate their ability to survive as independent, single-celled entities.

These amoeboid cells move by extending their cytoplasm to form pseudopodia, allowing them to glide across surfaces in search of food sources such as bacteria. Their movement and feeding strategy are essential for their survival as they acquire the necessary resources to thrive.

• Motility: Amoeboids are notable for their mobile nature, which is facilitated by pseudopodia.
• Feeding: During this phase, amoeboids act as active predators of bacteria, contributing to nutrient cycling in their ecosystem.
• Reproduction: Amoeboid cells undergo binary fission, an asexual reproduction process that increases their population.

The amoeboid stage is fundamental as each cell operates independently, and they are highly efficient in exploiting resources, which prepares them for the collective stages that follow when resources become limited.

Fruiting Body Formation

One of the most intriguing phases in the life cycle of cellular slime molds is when the amoeboid cells transform into a fruiting body. This typically occurs when environmental conditions become challenging, such as food scarcity.

In response, the individual amoeboid cells aggregate and collaborate to form a multicellular structure known as the fruiting body. This transformation is both incredible and vital for the propagation of spores, ensuring the species’ continuation.

• Aggregation Trigger: When resources are scarce, chemical signals prompt amoeboid cells to congregate.
• Differentiation: Within the structure, cells differentiate into various roles, forming spores and stalks within the fruiting body.
• Spore Dispersal: Elevated on tiny stalks, spores are dispersed into the environment, awaiting germination when conditions improve.

This form of collaboration in forming a fruiting body showcases an excellent example of the transition from single-celled to multicellular life forms, demonstrating a high level of biological complexity and adaptability.