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Questions and Answers
What is the primary role of bacteria in the nutrient cycle?
What is the primary role of bacteria in the nutrient cycle?
Most bacteria found in the human body are pathogenic.
Most bacteria found in the human body are pathogenic.
False
What branch of study focuses on the study of bacteria?
What branch of study focuses on the study of bacteria?
Bacteriology
Bacteria do not contain a __________ and rarely have membrane-bound organelles.
Bacteria do not contain a __________ and rarely have membrane-bound organelles.
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Match each bacterial activity with its purpose:
Match each bacterial activity with its purpose:
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What are the two evolutionary domains that prokaryotes consist of?
What are the two evolutionary domains that prokaryotes consist of?
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Bacterial fossils have distinctive morphology which can be used to examine their evolutionary history.
Bacterial fossils have distinctive morphology which can be used to examine their evolutionary history.
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Approximately when did the first forms of life appear on Earth?
Approximately when did the first forms of life appear on Earth?
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The process known as __________ involves the engulfment of ancient bacteria to form mitochondria and chloroplasts.
The process known as __________ involves the engulfment of ancient bacteria to form mitochondria and chloroplasts.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Study Notes
Characteristics of Bacteria
- Bacteria are prokaryotic microorganisms and mostly single-celled, typically a few micrometers in length.
- Ubiquitous organisms inhabiting diverse environments like soil, water, hot springs, radioactively impacted areas, and deep geological formations.
- Play essential roles in nutrient cycling, including nitrogen fixation and decomposition of organic matter.
Ecological Importance
- Extremophiles around hydrothermal vents and cold seeps convert compounds like hydrogen sulfide and methane into energy, supporting local ecosystems.
- Participate in various symbiotic relationships: mutualistic, commensal, and parasitic with plants and animals.
- Vital for processes like sewage treatment, oil spill remediation, fermentation in cheese and yogurt production, and biomining.
Human Interaction and Health Implications
- The human microbiome contains about 10^13 to 10^14 bacteria, primarily beneficial or innocuous; significant populations reside in the gut and on the skin.
- Pathogenic bacteria can cause serious infectious diseases, including cholera, tuberculosis, and anthrax.
- Antibiotics are critical in treating bacterial infections but contribute to rising antibiotic resistance; they're also used in agriculture.
Classification and Evolution
- Once categorized as plants (class Schizomycetes), bacteria are recognized as prokaryotes, distinct from eukaryotic cells which contain nuclei and organelles.
- In the 1990s, it was established that prokaryotes include two major domains: Bacteria and Archaea, diverging from a common ancestral origin.
- Early bacterial forms emerged approximately 4 billion years ago; they dominated life forms for about 3 billion years.
Ancestry and Evolutionary Significance
- Bacterial phylogeny can be reconstructed through gene sequences, revealing they diverged before Archaea and Eukarya.
- The most recent common ancestor of bacteria and archaea is thought to have been a hyperthermophile existing between 2.5 billion to 3.2 billion years ago.
- Endosymbiotic events led to the evolution of eukaryotic cells, with ancient bacteria forming mitochondria and chloroplasts through primary endosymbiosis.
Etymology
- The term "bacteria" is derived from the Neo-Latin "bacterium," which comes from the Ancient Greek word "βακτήριον" (baktḗrion), meaning "staff" or "cane," referencing the initial rod-shaped observations of these organisms.
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Description
This quiz covers the domain of microorganisms, focusing specifically on bacteria. Explore the characteristics, habitats, and significance of these prokaryotic organisms. Discover how bacteria have thrived in diverse environments since the early stages of life on Earth.
