Midterm 1 Questions Flashcards
Briefly explain why soil is the most diverse biological habitat on
earth
- Soil is characterized by heterogeneity
- Highly complex with many biotic and abiotic factors
define and describe environmental gradients in the soil
habitat at different spatial scales (landscape, profile, aggregate)
- Temp and seasons - fluctuate
- OM decreased with depth
- pH increases with depth (closer to PM)
- O2 diffusion decreases with depth
- Bulk density increases and pore space decreases
- Moisture is variable
Define soil texture, porosity and bulk density; describe how these attributes influence the soil habitat
- Texture - portions of sand/silt/clay
- Porosity - percentage of soil volume that is pore space
- Bulk density - mass of soil per unit volume including pore space
Affect plant growth, water availability, and microbial ecosystems
Explain how temperature and moisture influence soil microbial
communities and soil microbial activity
- Microbial activity increases until optimum temp is reached then a rapid decrease
- Microbial activity is a function of moisture (optimal moisture of 60% FC)
Principles of microbial metabolic classification
- Source of energy
- Source of reducing equivalents
- Source of carbon
List the bacterial group for cyanobacteria, halobacteria, and methanogens, SRBs
- Photolithotroph
- Photoorganotroph
- Chemolithotroph
- Chemoorganotroph
Describe the interactions between methanogens and SRBs
Competition between methanogens and SRBs: both will compete for hydrogen.
Explain why measuring soil microbial biomass is important
Microbial biomass reflects the living component of soil organic matter, which plays a crucial role in nutrient cycling, organic matter decomposition, and soil structure formation.
What are the three domains of life
Archaea, the Bacteria, and the Eukarya
List main structure in cell walls for bacteria, fungi, and plants
- Peptidoglycan (NAG and NAM
- Chitin (NAG) and some cellulose
- Cellulose
