Diversity

Classification & taxonomy

Naming, describing and classification of all living organisms.

Binomial nomenclature

A two-part scientific name (Genus species). Ex. Homo sapiens. Developed by Linnaeus to standardize naming.

Hierarchical classification

Organizes life from broad to specific: Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species.

Species concepts

How scientists define a species.

Biological species concept

A species is a group of organisms that can interbreed and produce fertile offspring. Limitation: Doesn't apply to extinct or asexual organisms.

Morphological species concept

A species is defined by physical characteristics (shape, size, structure). Useful for fossils and organisms that don't reproduce sexually. Limitation: Some species look alike but aren't the same (or vice versa).

Phylogenetic species concept

A species is the smallest group that shares a common ancestor, based on evolutionary history. Uses DNA and genetic evidence. Useful for classifying microorganisms and extinct species.

Phylogeny

Shows evolutionary relationships.

Dichotomous key

A step-by-step tool for identifying organisms using pairs of contrasting traits. Always leads to a specific name or category.

The 6 kingdoms

Way to classify all living organisms based on characteristics like cell type, how they obtain nutrients, and how they reproduce.

Archaea

Prokaryotic (no nucleus), live in extreme environments (extremophiles), cell walls with unique lipids.

Bacteria

Prokaryotic, very diverse, come in shapes like cocci (spherical), bacilli (rod-shaped), and spirilla (spiral); use Gram staining to classify.

Protista

Eukaryotic (nucleus present), mostly single-celled, found in water; some are like plants (photosynthetic), animals (move, consume), or fungi (absorb nutrients).

Fungi

Eukaryotic, heterotrophic by absorption, have cell walls made of chitin, reproduce using spores, consist of hyphae (thread-like structures).

Plantae

Eukaryotic, autotrophic (make food via photosynthesis), have cell walls made of cellulose, multicellular.

Animalia

Eukaryotic, heterotrophic by ingestion (consume food), multicellular, no cell walls, complex body systems.

Viruses

Not in any kingdom; not living. Made of DNA or RNA inside a protein coat (capsid).

Lytic cycle

Immediate replication and cell destruction.

Lysogenic cycle

Viral DNA hides in host DNA, activates later.

Retroviruses

It's a type of virus that inserts a DNA copy of its RNA genome into the DNA of a host cell that it invades, changing its genome.

Biodiversity

Variety of life on Earth at all its levels, from genes to ecosystems.

Types of biodiversity

Genetic diversity, species diversity, ecosystem diversity.

Importance of biodiversity

Ecological: Healthy ecosystems = more stability and resilience; Economic: Provides resources (food, timber, medicine, tourism); Medicinal: Many drugs come from natural compounds in plants, fungi, bacteria.

Threats to biodiversity

Habitat loss, pollution, climate change, invasive species, overuse.

Timeline of life

Water - Land, Simple - Complex, Luca - Today, ~ 3.6 BYA.