Biology

Hexapoda

Hexapoda — six-legged arthropods and their major groups

Hibernation

Hindbrain

Hindbrain (Rhombencephalon)

Hinge teeth

Hinge teeth (bivalve shell dentition)

Histology

Histone

Histone (chromatin protein)

Holozoa

Homeostasis

Homeostasis: biological self-regulation and internal stability

Homologous chromosome

Homologous chromosomes

Homology

Homology (biology): traits shared through common ancestry

Horizontal gene transfer

Horizontal gene transfer: mechanisms, evolution, and significance

Hormone

Hormone: chemical messengers in animals and plants

Horn (anatomy)

Horn (anatomy): structure, function and cultural uses

Host (biology)

Host defence peptide

Host defence peptide (antimicrobial peptide)

Hox gene

Hox gene family: master regulators of body patterning

Human biology

Human biology: form, function, variation and evolution of Homo sapiens

Human body

Human body: structure, function, development and health

Human cloning

Human genome

Human microbiome

Human reproductive system

Human reproductive system: structure, function, and health

Human skeleton

Human skeleton: structure, development, functions, and variation

Humerus

Humerus (upper arm bone)

Humoral immunity

Humoral immunity is the branch of the immune response mediated by soluble molecules — notably antibodies, complement, and antimicrobial peptides — that neutralize and clear pathoge

Hybrid vigour

Hybrid vigour (heterosis)

Hydrogenosome

Hydrogenothermaceae

Hydrogenothermaceae: thermophilic, hydrogen‑oxidizing bacteria of geothermal habitats

Hymenium

Hyperthermophile

Hyperthermophile: organisms adapted to very high temperatures

Hypertrophy

Hypothalamus

IC50

IC50: definition, measurement, interpretation, and applications

IC50 is the concentration of a substance that produces 50% inhibition of a defined biological function. This article explains its meaning, measurement, limitations, and common uses

Ice algae

Ice algae: biology, ecology and roles in snow and sea ice environments

Ichneumon

Ichthyology

Ichthyology: The Scientific Study of Fishes

Identical twins

Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis: overview, features, diagnosis and management

Ileum

Imago

Imago (adult stage of an insect)

Immortality

Immune system

Immunity (medical)

Immunology

Inbreeding

Inbreeding: mating of closely related organisms

Incisor

Incisor: structure, function, and variation in mammals

Infant mortality

Infant mortality: definition, measurement, causes, and public health significance

Infertility

Infertility: Causes, Diagnosis, and Treatment Options