CMI Mold Biology & Ecology 2 — Questions and Answers
Question 1: Which mold genus is most commonly found in outdoor air samples and serves as the primary reference for background environmental mold levels?
- Stachybotrys
- Chaetomium
- Cladosporium (Correct answer)
- Fusarium
Correct answer: Cladosporium
Cladosporium is one of the most abundant outdoor molds worldwide and consistently dominates background air samples, making it the standard benchmark for comparing indoor-to-outdoor spore concentrations.
Question 2: What broad temperature range can most indoor mold species tolerate and grow within?
- 32°F–50°F (0°C–10°C)
- 40°F–100°F (4°C–38°C) (Correct answer)
- 65°F–75°F (18°C–24°C)
- 95°F–115°F (35°C–46°C)
Correct answer: 40°F–100°F (4°C–38°C)
Most indoor molds are mesophilic and can grow across a wide range of approximately 40°F to 100°F (4°C–38°C), which encompasses virtually all indoor and temperate outdoor temperatures.
Question 3: Which mold genus is the biological source of the antibiotic penicillin and is also frequently isolated from water-damaged building materials?
- Aspergillus
- Alternaria
- Penicillium (Correct answer)
- Trichoderma
Correct answer: Penicillium
Penicillium species produce penicillin and are also common colonizers of water-damaged insulation, paper, and food products, producing a distinctive blue-green color and musty odor.
Question 4: What are asexual spores produced externally on mold hyphae or conidiophores called?
- Ascospores
- Basidiospores
- Zygospores
- Conidia (Correct answer)
Correct answer: Conidia
Conidia (singular: conidium) are asexually produced spores formed on the exterior of specialized hyphae called conidiophores and are the most common type of spore encountered in mold air and surface sampling.
Question 5: Which single environmental condition is the most critical factor promoting mold growth on building materials?
- Low carbon dioxide levels
- High foot traffic in occupied spaces
- Persistent moisture or water intrusion (Correct answer)
- Exposure to ultraviolet light from windows
Correct answer: Persistent moisture or water intrusion
Persistent moisture or water intrusion is the single most critical factor for mold growth, which is why all remediation guidance — including the EPA's — mandates eliminating the moisture source before addressing mold.
Question 6: What is 'hyphal fragmentation' in the context of mold biology?
- Hyphae breaking into individual cells that can spread and establish new colonies (Correct answer)
- The enzymatic process by which molds digest cellulose substrates
- The formation of sexual spores within a protected fruiting body
- The breakdown of mold cell walls during chemical treatment
Correct answer: Hyphae breaking into individual cells that can spread and establish new colonies
Hyphal fragmentation occurs when mycelium breaks into individual cells called arthrospores or hyphal fragments, each capable of dispersing and establishing a new mold colony independent of spore production.
Question 7: Which life cycle stage describes when a mold spore begins to grow after landing on a suitable substrate?
- Sporulation
- Germination (Correct answer)
- Sporogenesis
- Anastomosis
Correct answer: Germination
Germination is the stage at which a mold spore activates and extends an initial hyphal tube called a germ tube when conditions of moisture, temperature, and nutrient availability are adequate.
CMI Mold Biology & Ecology 2
Which mold genus is most commonly found in outdoor air samples and serves as the primary reference for background environmental mold levels?