CMI Mold Biology & Ecology 1 — Questions and Answers
Question 1: What is the primary reproductive structure of mold that allows it to spread through the air?
- Hyphae
- Mycelium
- Spores (Correct answer)
- Rhizoids
Correct answer: Spores
Mold reproduces by releasing spores, which are microscopic particles that travel through the air and colonize new surfaces when conditions of moisture, temperature, and nutrients are favorable.
Question 2: Which of the following best describes the vegetative body of a mold fungus?
- Spore
- Mycelium (Correct answer)
- Conidium
- Basidiospore
Correct answer: Mycelium
The mycelium is the vegetative part of a fungus, consisting of a network of branching thread-like structures called hyphae that absorb nutrients from the substrate.
Question 3: At approximately what minimum relative humidity do most common indoor molds begin to grow?
- 30%
- 40%
- 60% (Correct answer)
- 80%
Correct answer: 60%
Most common indoor molds begin to grow when relative humidity exceeds approximately 60%, which is why building scientists recommend keeping indoor RH below this threshold.
Question 4: Which fungal genus is commonly called 'black mold' and requires chronically wet, cellulose-rich materials to grow?
- Aspergillus
- Cladosporium
- Penicillium
- Stachybotrys (Correct answer)
Correct answer: Stachybotrys
Stachybotrys chartarum is commonly called 'black mold' and requires consistently saturated cellulose-rich materials such as drywall paper or ceiling tiles, making it a marker of chronic water intrusion.
Question 5: What is the term for the individual thread-like filaments that collectively form the body of a mold?
- Conidiophores
- Sporangia
- Hyphae (Correct answer)
- Rhizomorphs
Correct answer: Hyphae
Hyphae are the individual microscopic filaments that, when massed together, form the mycelium — the main structural and nutritive body of a mold fungus.
Question 6: Which term describes a mold adapted to grow in low-moisture or dry environmental conditions?
- Thermophilic
- Xerophilic (Correct answer)
- Hydrophilic
- Mesophilic
Correct answer: Xerophilic
Xerophilic molds are adapted to grow in low-moisture or dry conditions, allowing them to colonize surfaces even when relative humidity is below levels that support most other mold species.
Question 7: What is the primary nutrient source for most molds found growing on indoor building materials?
- Minerals in concrete
- Nitrogen in the air
- Cellulose and other organic materials (Correct answer)
- Iron compounds in metal pipes
Correct answer: Cellulose and other organic materials
Most indoor molds obtain nutrition by breaking down cellulose and other organic materials found in drywall paper, wood studs, carpet backing, and other common building components.
CMI Mold Biology & Ecology 1
What is the primary reproductive structure of mold that allows it to spread through the air?