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Bacteria Characteristics and Classification
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Question
What are the main characteristics of prokaryotic cells in the kingdoms Archaebacteria and Eubacteria?
Answer
Single-celled, no membrane-bound organelles, smaller ribosomes, one chromosome, reproduce by binary fission.
Question
How does the structure of a generalized bacterial cell support its survival in harsh environments?
Answer
Cell wall provides structure; capsule protects from immune system; flagella enable movement; pili assist in clinginess.
Question
What distinguishes Archaebacteria from Eubacteria in terms of environment and evolution?
Answer
Archaebacteria are older, live without oxygen, in harsh conditions; Eubacteria are more successful, more common.
Question
Describe the three main bacterial shapes and give an example of each.
Answer
Bacillus (rod, e.g., E. coli); Coccus (round, e.g., gonorrhea); Spirilla (spiral, found in freshwater).
Question
Explain the differences among obligate aerobes, obligate anaerobes, and facultative anaerobes.
Answer
Obligate aerobes need O₂; obligate anaerobes grow only without O₂; facultative anaerobes survive with or without O₂.
Question
What nutritional strategies do bacteria use, and how do autotrophic bacteria produce their food?
Answer
Most are heterotrophs; some are parasitic; autotrophic bacteria are photosynthetic or chemosynthetic, using sunlight or chemicals.
Question
How does the Gram stain differentiate bacteria, and what does each group indicate about bacterial structure and antibiotic resistance?
Answer
Gram-positive absorb stain, indicating thick cell wall; Gram-negative do not, more resistant to antibiotics.
Question
Describe the process and significance of bacterial reproduction through binary fission and conjugation.
Answer
Binary fission: DNA replicates, cell divides into two; conjugation transfers plasmids via cytoplasmic bridge, enabling gene exchange.
Question
Why are bacteria classified into two kingdoms, and which group is considered the most ancient?
Answer
Classification based on genetics and environment; Archaebacteria are the oldest group.
Question
What roles do bacteria play in the environment and human health?
Answer
Decomposers, beneficial in intestines, some cause diseases, some produce food like yogurt.