Biology Classification and Taxonomy Quiz

Classification and Taxonomy

• Classification groups organisms based on shared characteristics.
• Carolus Linnaeus developed the first formal classification system.
• Taxonomy identifies, names, and categorizes species based on natural relationships.
• Binomial nomenclature assigns a two-part scientific name: genus and species.
• A taxon refers to any group of organisms that share a common identity.

Taxonomic Ranks

• Genus includes closely related species sharing a common ancestor.
• Family comprises related genera.
• Order consists of related families.
• Class encompasses related orders.
• Phylum (or division) contains related classes.
• Kingdom includes multiple phyla or divisions.
• Domain is the broadest taxon category, incorporating one or more kingdoms.

Domains and Kingdoms

• Three domains exist: Bacteria, Archaea, and Eukarya.
• Six kingdoms include: Eubacteria, Archaea, Protista, Fungi, Plantae, Animalia.
• Domain Bacteria represents prokaryotes with peptidoglycan cell walls.
• Domain Archaea includes prokaryotes without peptidoglycan, found in extreme conditions.
• Domain Eukarya features eukaryotes, which can be unicellular or multicellular.

Characteristics of Domains and Kingdoms

• Kingdom Fungi consists of eukaryotic organisms that absorb nutrients and lack mobility.
• Kingdom Plantae is made up of multicellular eukaryotes with cellulose cell walls.
• Kingdom Animalia contains multicellular eukaryotes without cell walls, organized into tissues.

Bacterial Structure and Reproduction

• Bacteria are microscopic prokaryotes characterized by structures like nucleoid, pili, capsule, and flagella.
• Bacterial chromosomes are circular and found in the nucleoid.
• Binary fission is the process by which bacteria replicate into two genetically identical cells.
• Conjugation involves the exchange of genetic material between two bacterial cells.

Bacterial Metabolism and Survival

• Bacteria can be photoautotrophs (photosynthesis), chemoautotrophs (chemosynthesis), aerobes (require oxygen), or anaerobes (do not need oxygen).
• Survival endospores allow bacteria to endure harsh environmental conditions.

Viruses

• Viruses consist of a nonliving strand of genetic material encased in a protein coat (capsid).
• The lytic cycle involves immediate viral gene expression after infection, resulting in new virus assembly and host cell lysis.
• The lysogenic cycle integrates viral DNA into the host's genome, remaining dormant before triggering the lytic cycle.
• Retroviruses contain RNA and exhibit complex replication cycles.

Prions and Protists

• Prions are infectious proteins that can cause disease and cause other proteins to mutate.
• Protists are diverse eukaryotes that can behave as plant-like, animal-like, or fungus-like organisms, often living in aquatic environments.

Fungi Characteristics

• Fungi are eukaryotic, with cell walls made of chitin and lacking chloroplasts.
• Reproduction occurs asexually (budding, fragmentation) and sexually (spore production).
• Fungi obtain nutrients as saprophytes (decomposers), parasites, or mutualists associated with plants.

Nutritional Modes of Fungi

• Saprophytic fungi decompose dead organic material.
• Parasitic fungi feed on living cells, using specialized hyphae called haustoria to penetrate host tissues.
• Mutualistic fungi benefit from symbiotic relationships with plants, aiding in nutrient absorption.

Classification Criteria

• Organisms are classified based on cell type and structure.
• Protistas are eukaryotic and cannot form organs, distinguishing them in the biological classification system.
• Viruses lack cellular structure, leading to their exclusion from traditional biological classification.