Genetics

Antibiotic resistance is an example of natural selection in action: bacteria with a random mutation that allows them to survive antibiotics reproduce, passing on resistance — a major public health threat.

Some characteristics are influenced by both genes and environment — for example, height has a strong genetic basis but is also affected by nutrition.

Selective breeding (artificial selection) is when humans choose which organisms reproduce to pass on desired characteristics, e.g. breeding cattle for more milk or dogs for temperament.

Chromosomes are long, coiled-up molecules of DNA found in the nucleus of cells; humans normally have 46 chromosomes (23 pairs).

Darwin gathered key evidence for evolution on the Galápagos Islands, where the variation among finches (especially their beak shapes) — collected during the 1831–36 voyage of HMS Beagle — helped inspire his theory of natural selection.

DNA (deoxyribonucleic acid) is a double helix molecule made of two strands of nucleotides; it carries the genetic instructions for building and running an organism.

Charles Darwin and Alfred Russel Wallace independently developed the theory of evolution by natural selection; Darwin published On the Origin of Species in 1859.

Environmental variation is caused by factors such as diet, exercise, sunlight, and experience; examples include language spoken, body mass, and scars.

Extinction occurs when every member of a species dies and no more can reproduce; it can be caused by environmental change, disease, competition, or predation.

A gene is a section of DNA that carries the instructions for making a specific protein, which determines a characteristic of the organism.