Biology

Evolution

The slow change in a population’s traits over time, leading to new species forming from existing ones.

Population

A group of the same species living in one area.

Species

A group of organisms that can interbreed and produce fertile offspring.

Convergent evolution

Different species develop similar traits due to similar environments, not because of a common ancestor.

Vestigial structures

Leftover traits with little or no function today, useful to ancestors (e.g., the appendix).

Imperfect structures

Traits that are not well-designed for their current function (e.g., the human eye).

Comparative embryology

The study of early embryos of different species that look similar, suggesting shared ancestry.

Comparative biochemistry

The principle that all life shares similar DNA, proteins, and chemical processes.

Jean-Baptiste Lamarck

A scientist who believed in use and disuse, proposing that acquired traits could be inherited.

Charles Darwin

The scientist who developed the theory of natural selection and wrote On the Origin of Species.

Panspermia

The idea that life (or its building blocks) came from space.

Relative dating

Method to determine the age of fossils based on rock layers (deeper = older).

Absolute dating

Technique using radioactive decay (like carbon-14) to determine the exact age of fossils.

Homologous structures

Structures with a common ancestry but different functions.

Analogous structures

Structures with similar functions but different ancestries.

Natural selection

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

Stabilizing selection

Natural selection that favors average traits.

Directional selection

Natural selection that favors one extreme trait.

Disruptive selection

Natural selection that favors both extreme traits.

Morphological adaptations

Physical traits that help organisms survive.

Gradualism

The concept of gradual, steady change in a population over time.

Punctuated equilibrium

The theory that evolution occurs in rapid bursts followed by long periods of stability.

Speciation

The process by which new species form through reproductive isolation and genetic changes.

Genetic drift

Random changes in allele frequencies within a population.

Gene flow

Movement of genes between populations.

Endosymbiotic theory

The hypothesis that eukaryotic cells evolved from prokaryotic cells engulfing each other.

Cenozoic Era

The current geological era, known as the age of mammals.

Mass extinction

A rapid decrease in the biodiversity on Earth, often caused by catastrophic events.

Adaptive radiation

The rapid evolution of many species from a common ancestor due to various environmental opportunities.

Artificial selection

The process by which humans select which organisms breed based on desired traits.

Hardy-Weinberg Principle

A principle stating that allele frequencies in a population remain constant under specific conditions.

Allele

Different forms of a gene.