Problem 10 - Biology Concepts and Applications

Question

A ____ helps to break down rocks and form soil. a. chytrid c. mycorrhiza b. glomeromycete d. lichen

Step-by-Step Solution

Answer

The correct answer is 'd. lichen'.

Step 1: Identify the Main Function

First, we need to recognize the function mentioned in the question: helping to break down rocks and form soil. This process is primarily related to biological and chemical weathering.

Step 2: Understand Rock and Soil Formation

Consider how rocks break down and soil forms. This process involves various organisms, some of which release acids or other substances that contribute to rock weathering.

Step 3: Analyze Each Option

Evaluate each given option: - Chytrids are fungi primarily known for living in water and decomposing organic matter. - Mycorrhiza refers to a symbiotic association between fungi and plant roots. - Glomeromycetes are a group of fungi mainly forming mycorrhizal relationships and benefiting plants. - Lichen is a mutualistic relationship between fungi and algae or cyanobacteria, often colonizing bare rocks and breaking them down.

Step 4: Determine the Correct Answer

From the analysis, lichens are the organisms that primarily contribute to breaking down rocks by secreting acids, thus aiding in soil formation.

Key Concepts

Biological Weathering

Biological weathering is a crucial natural process where living organisms contribute to the breakdown of rocks. This process involves

• Physical actions such as root expansion, where plant roots grow into cracks in the rock, causing it to split apart,
• and chemical actions, where organisms produce substances that chemically react with the rock.

Lichens are a great example of biological weathering in action. They grow on rocks and secrete acids that dissolve minerals in the rocks. Over time, this process weakens the rock structure, enabling further disintegration. Biological weathering is essential for transforming rigid rock surfaces into finer particles. This promotes the formation of new materials and initiates a chain reaction that involves other weathering forms like physical and chemical processes.

Rock Breakdown

Rock breakdown, or rock erosion, is a step-by-step process of disassembling rocks into smaller particles. Different factors contribute to rock breakdown, including weathering, erosion, and human activities. Weathering is the initial phase here and is classified into physical, chemical, and biological types.

• Physical weathering involves mechanical forces splitting and cracking rocks,
• while chemical weathering involves chemical reactions that alter the rock's material.
• But biological weathering leverages the abilities of organisms like lichens.

Lichens, tiny but mighty, cling to rocks in harsh environments and start the breakdown process, making nutrients and minerals accessible for further soil formation. In doing so, they play a pivotal role in ecosystems by transforming bare rock landscapes into nutrient-rich environments supportive of varied life forms.

Soil Formation

Soil formation is the natural result of rock breakdown combined with the accumulation of organic matter. It is influenced by climate, organisms, topography, and time. The process begins with the weathering of rocks into smaller particles, followed by the addition of organic material from decomposing plants and animals.

Factors like lichens not only break down rocks but also contribute to the soil formation by initiating the accumulation of organic materials.

• As lichens break down rock, the resulting mineral particles mix with organic debris from dead lichens and other organisms.
• This forms a primitive soil layer, providing a medium for other plants to root and grow.

The continuous interplay of weathering and organic matter accumulation turns barren rock surfaces into arable land over long periods. Thus, soil formation is a key environmental process that facilitates plant growth, water storage, and ultimately sustains life on Earth.