Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

Which group of organisms is known for their ability to thrive in extreme environments?

1. Archaebacteria

2. Eubacteria

3. Protista

4. Phaeophyta

The correct answer is: Archaebacteria

The group of organisms recognized for their remarkable ability to thrive in extreme environments is Archaebacteria. These microorganisms are often found in habitats that would be hostile to most other forms of life, including extreme temperatures, high salinity, low pH, and high pressure. This resilience is attributed to their unique biochemical and genetic characteristics, which allow them to adapt to such conditions. For example, some Archaebacteria can live in extreme heat, such as those found in hydrothermal vents, while others can survive in highly acidic environments like hot springs. Their cell membranes and metabolic pathways are distinct from those of eubacteria, enabling these organisms to maintain stability and function under conditions that would typically denature proteins and disrupt cellular processes in other organisms. In contrast, eubacteria, while diverse and widespread, generally prefer more moderate habitats. Protista includes a variety of organisms, many of which are found in aquatic environments but do not specifically thrive in extreme conditions. Phaeophyta, or brown algae, are primarily marine organisms that inhabit cooler ocean waters and do not exhibit the extreme adaptability associated with Archaebacteria.