Origin and Evolution of Life on Earth

Earth Formation

Earth formed 4.6 billion years ago from cosmic materials.

Prokaryotic Life

First life forms, including Archaebacteria and Eubacteria.

Anaerobic Environments

Habitats lacking oxygen where early life thrived.

Oxygen Revolution

Cyanobacteria produced oxygen through photosynthesis.

Eukaryotic Life

Complex cells emerged 2 billion years ago.

Cambrian Explosion

Major animal groups appeared 541 million years ago.

Vascular Plants

Plants adapted to land, enabling terrestrial ecosystems.

Arthropods

Invertebrates that adapted to land environments.

Tetrapods

Four-limbed vertebrates transitioning from sea to land.

Dinosaurs Emergence

Dinosaurs appeared around 230 million years ago.

Early Mammals

Mammals began to rise 66 million years ago.

Hominid Development

Evolution of human ancestors 4 to 2 million years ago.

Anthropocene Epoch

Current geological epoch marked by human impact.

Geologic Time Scale

Calendar of Earth's history events and periods.

Pre-Cambrian Eons

Longest eon, covering most of Earth's history.

Phanerozoic Eon

Recent eon divided into Paleozoic, Mesozoic, Cenozoic.

Paleozoic Era

Era of ancient life, 541 to 252 million years ago.

Mesozoic Era

Era of middle life, 252 to 66 million years ago.

Cenozoic Era

Era of recent life, 66 million years ago to present.

Cambrian Period

Known for the Cambrian Explosion of life.

Ordovician Period

Diverse marine life and first vertebrates evolved.

Devonian Period

Age of Fish; first amphibians and trees appeared.

Permian Period

Evolution of reptiles; ended with largest extinction.

Triassic Period

Early dinosaurs and first mammals appeared.

Jurassic Period

Dominance of dinosaurs and first birds evolved.

Cretaceous Period

Diversification of dinosaurs; ended with mass extinction.

Paleogene Period

Mammals diversified; early primates set stage for humans.

Neogene Period

Evolution of hominids and grazing mammals.

Quaternary Period

Lasts from 2.58 million years ago to present.

Homo sapiens

Modern humans, dominant species on Earth.

Continental Drift

Movement of continents affecting climate and species.

Abiogenesis

Life emerged from non-living matter through reactions.

RNA World Hypothesis

Replicating RNA crucial for early life stages.

Panspermia

Life may have originated from outside Earth.

Photosynthetic Autotrophs

Organisms producing energy through photosynthesis.

Plant Characteristics

Multicellular eukaryotes with cellulose cell walls.

Mosses

Small, non-vascular plants reproducing via spores.

Ferns

Large, vascular plants with feathery leaves.

Gymnosperms

Seeds exposed on cone scales, not fruits.

Angiosperms

Produce flowers and seeds within fruits.

Animal Characteristics

Multicellular eukaryotes, heterotrophic, lacking cell walls.

Porifera

Simple, porous animals like sponges.

Cnidaria

Radially symmetrical animals like jellyfish.

Platyhelminthes

Flatworms, often parasitic or free-living.

Nematoda

Roundworms, diverse in habitats.

Annelida

Segmented worms like earthworms.

Arthropoda

Invertebrates with exoskeletons, jointed limbs.

Mollusca

Soft-bodied animals, often with shells.

Echinodermata

Marine animals with radial symmetry, like starfish.

Chordata

Animals with a notochord, including vertebrates.

Microorganism Characteristics

Unicellular or simple multicellular organisms.

Bacteria

Prokaryotic cells crucial for nutrient cycling.

Fungi

Eukaryotic decomposers forming symbiotic relationships.

Viruses

Non-living entities requiring host cells for reproduction.

Protists

Eukaryotic, mostly unicellular organisms like algae.

Natural Selection

Survival of traits enhancing fitness in populations.

Artificial Selection

Humans breed individuals for desired traits.

Giraffe Neck Length

Longer necks favored for accessing food.

Peppered Moths

Dark moths favored for camouflage during Industrial Revolution.

Natural Selection

Process where organisms better adapted survive.

Peppered Moths

Dark moths thrived due to soot camouflage.

Selective Breeding

Intentional mating for specific characteristics.

Dog Breeds

Humans select traits like size and color.

Genetic Drift

Random allele frequency changes in populations.

Founder Effect

New population starts from a small group.

Bottleneck Events

Population size drastically reduced by catastrophe.

Mutation

Heritable DNA sequence change in organisms.

Antibiotic Resistance

Bacterial mutations confer survival against antibiotics.

Evolutionary Relationships

Patterns of ancestry among different species.

Molecular Data

Information from DNA, RNA, and proteins.

Protein Sequences

Reflect genetic changes over evolutionary time.

Homologous Structures

Anatomical features from a common ancestor.

Analogous Structures

Similar functions without common evolutionary origin.

Fossils

Preserved remains providing evidence of ancient life.

Developmental Characteristics

Traits used for categorizing organisms in taxonomy.

Embryonic Development

Early vertebrate embryos share similar appearances.

Metamorphosis

Life cycle changes in butterflies and moths.

Mendelian Genetics

Study of inheritance patterns in traits.

Sex-Linked Traits

Traits associated with genes on sex chromosomes.

Pedigree Analysis

Charting family traits to understand inheritance.

Colorblindness

X-linked recessive trait affecting vision.

Carrier

Individual with one recessive allele, not expressed.

Hemophilia

X-linked recessive disorder affecting blood clotting.

Hypophosphatemic Rickets

X-linked dominant condition causing phosphate deficiency.

Webbed Toes

Recessive trait causing webbing in frog toes.

Genotypic Ratio

Proportion of different genotypes in offspring.

Phenotypic Ratio

Proportion of different phenotypes in offspring.

Dominant Trait

Trait that masks the expression of another.

Recessive Trait

Trait that is masked by a dominant trait.

P Generation

Parental generation in Mendelian experiments.

F1 Generation

First generation of offspring from P generation.

F2 Generation

Second generation from self-pollination of F1.

Self-Pollination

Process where a plant fertilizes itself.

True Breeding

Plants that consistently produce the same trait.

Mendel's Law of Dominance

Dominant traits mask recessive traits in offspring.

Tongue Rolling

Dominant trait for rolling the tongue.

Heterozygous

Having two different alleles for a trait.

Autosomal Trait

Trait not linked to sex chromosomes.

X-linked Trait

Trait associated with genes on the X chromosome.

Probability of Offspring

Likelihood of specific traits in offspring.