Biology

Lipid bilayer: structure, formation, and biological roles Lipid bilayer Comprehensive overview of the lipid bilayer: its structure, self-assembly from phospholipids, physical properties, embedded proteins, biological functions, history and experimental…

Lipopolysaccharide (LPS): structure, function, and medical importance Lipopolysaccharide Lipopolysaccharides are complex molecules on Gram-negative bacterial outer membranes that provoke innate immune responses; they are central to endotoxin activity, vaccine design, a…

Lissamphibia: the living amphibians — groups, traits, history, and importance Lissamphibia Lissamphibia is the clade that contains all living amphibians: frogs, salamanders and caecilians. Overview of classification, shared traits, fossil context, ecological roles and co…

List of biochemistry topics An organized overview of principal biochemistry subjects, grouped by concept, technique, metabolism, molecular components, applications, and historical context for study and refere…

List of Biologists Overview and organization of notable biologists: roles, major fields, historical development, examples of influential scientists, and how lists are compiled and used.

Listeria (bacterial genus and public‑health relevance) Listeria Listeria is a genus of Gram‑positive bacteria, including species that can cause listeriosis. Notable for surviving cold storage and posing risks to pregnant people, neonates, elder…

Litoria — Australasian tree frog genus Litoria Litoria is a genus of hylid tree frogs native to Australasia and nearby islands, notable for arboreal adaptations, varied life histories, and conservation concerns across a wide ra…

Liver (hepatic organ) Liver The liver is a large abdominal organ central to metabolism, bile production, detoxification, and storage. This article outlines its structure, key functions, clinical importance, a…

Living fossil: species showing long-term morphological continuity Living fossil A living fossil is a modern species that closely resembles its distant fossil relatives. This article explains the concept, causes of morphological stasis, prominent examples, scie…

Local extinction (extirpation): causes, consequences and recovery Local extinction Local extinction (extirpation) occurs when a species disappears from part of its range. This article outlines definitions, causes, ecological impacts, and approaches to reintroduct…

Locomotion: movement and mechanisms in animals, microbes and machines Locomotion Locomotion is active movement by organisms or devices that changes position. This article covers biological mechanisms, common forms (walking, swimming, flying), evolutionary origi…

Longevity: understanding long life, causes, and implications Longevity Longevity refers to long life or increased life expectancy. This article explains definitions, causes, historical interest, research directions, practical approaches, and societal…

Lophophore: the ciliated tentacle feeding organ of lophophorate animals Lophophore A ciliated, tentacular feeding structure found in several aquatic invertebrate phyla (brachiopods, bryozoans, entoprocts, phoronids). It functions in suspension feeding and sometim…

Lophotrochozoa: a major clade of bilaterian animals Lophotrochozoa Lophotrochozoa are a molecularly defined clade of protostome animals that includes mollusks, annelids and several lesser-known phyla; they lack a single unifying morphology but sha…

Loricifera — tiny loricate animals of marine sediments Loricifera Loricifera are microscopic marine animals living between sediment grains. Described in 1983, they form a distinct ecdysozoan phylum notable for their protective lorica and for spec…

Lufengosaurus — Early Jurassic sauropodomorph from China Lufengosaurus Lufengosaurus is an early sauropodomorph dinosaur from the Lower Jurassic Lufeng Basin of southwestern China, known from comparatively complete skeletons and important for studies…

Lung: structure, function, development and importance Lung The lung is the primary respiratory organ in most vertebrates. This article explains its structure, how breathing and gas exchange work, evolutionary origins, and why lungs matter…

Luria–Delbrück experiment (Fluctuation Test) Luria–Delbrück experiment A 1943 bacterial genetics experiment demonstrating that mutations arise randomly, before selection, by measuring variation in resistance across independent cultures.

Luteinizing hormone (LH) Luteinizing hormone Luteinizing hormone (LH) is a pituitary gonadotropin that regulates ovulation, corpus luteum function and testosterone production; it is key to reproductive physiology and clinical…

Lycoperdon umbrinum — the umber-brown puffball Lycoperdon umbrinum A puffball fungus in the genus Lycoperdon found across Europe, China and North America; small to medium-sized, saprotrophic, notable for its brown peridium and powdery spore mass w…

Lycopsis — extinct Miocene South American metatherian carnivore Lycopsis Lycopsis is a Miocene borhyaenid metatherian from South America. Fossils indicate a partly terrestrial ambush predator with features linking arboreal ancestors and ground‑living bo…

Lymph node Small, encapsulated immune organs that filter lymph and coordinate immune responses; located throughout the body and important in infection control, cancer staging, and immune surv…

Lymphatic system: structure, roles, and clinical relevance Lymphatic system The lymphatic system is a unidirectional vascular network that returns interstitial fluid to the blood, supports immunity, and transports absorbed fats; it includes vessels, nodes,…

Lymphocyte Lymphocytes are a class of white blood cells central to vertebrate immunity, including B cells, T cells and natural killer cells that provide antibody production, cell-mediated def…

Lysis: rupture of cell membranes or walls causing cell death Lysis Lysis is the loss of cellular integrity when a membrane or wall breaks down, caused by viruses, enzymes, immune attack, osmotic stress or toxins; significant in microbiology, medic…

Lysosome: cellular digestive organelle and recycling center Lysosome Membrane-bound organelles in eukaryotic cells that contain acid hydrolases to degrade biomolecules, recycle components, and contribute to immunity and disease.

Lysozyme Lysozyme is a small antimicrobial enzyme of the innate immune system that breaks down bacterial cell walls; important in biology, medicine and structural biochemistry.

Macrococcus Macrococcus is a genus of Gram-positive, catalase- and oxidase-positive cocci related to staphylococci, primarily found on animals; relevant to veterinary microbiology and antimicr…

Macroevolution: patterns, processes, and evidence across large evolutionary scales Macroevolution Macroevolution describes large-scale evolutionary change above the population level — origins of new taxa, long-term trends in the fossil record, and methods used to study them.

Macrolepidoptera: overview, composition, and significance Macrolepidoptera Macrolepidoptera is a modern grouping of larger moths and butterflies within the order Lepidoptera, assembled to reflect evolutionary relationships. It includes familiar superfamil…

Macrophage: tissue phagocyte and immune regulator Macrophage Macrophages are versatile immune cells that engulf debris and microbes, present antigens, and regulate inflammation. They arise from monocytes or embryonic precursors and play role…

Major histocompatibility complex (MHC) Major histocompatibility complex The major histocompatibility complex is a set of cell-surface proteins encoded by a diverse gene family that present peptide fragments to T cells and shape adaptive immune response…

Malacology: The Scientific Study of Molluscs Malacology Malacology is the branch of zoology concerned with molluscs — their diversity, structure, life histories, ecological roles, human uses, and conservation. This article summarizes sc…

Mammaliaformes: mammals and their closest extinct relatives Mammaliaformes Mammaliaformes groups living mammals and their nearest extinct kin. Covers key traits (teeth, lactation, fur, jaw and ear changes), major fossils, evolutionary history and why this…

Mammalogy: The Scientific Study of Mammals Mammalogy An overview of mammalogy: defining characteristics of mammals, main subfields, methods, history, conservation importance, and career paths in the study of mammals.

Mammary gland: structure, function, development, and clinical notes Mammary gland Glandular organs in mammals that produce milk for offspring. Covers anatomy, development, hormonal control of lactation, species variation, and common clinical issues.

Mandible (lower jaw) Mandible The mandible is the lower jawbone in jawed vertebrates. This article explains its anatomy, development, evolution, functions, and clinical significance across species, with emphasi…

Mantle (mollusc anatomy) Mantle (mollusc) The mantle is the dorsal body wall of molluscs that encloses the visceral organs, forms the mantle cavity, and in many species secretes the shell and related structures.

Marine biology: the study of life in the oceans Marine biology Marine biology is the scientific study of organisms that live in the ocean and their interactions with the marine environment, spanning ecology, behavior, physiology, and conservat…

Mast cell: tissue-resident immune cell involved in allergy, defense and repair Mast cell Mast cells are tissue-resident leukocytes formed in bone marrow that store histamine and other mediators. They mediate allergic reactions, fight parasites, aid wound healing, and i…

Mating: Biological reproduction, mechanisms and behaviors Mating Overview of mating across animals, plants and fungi: definitions, mechanisms (internal/external fertilization), hermaphroditism, mating systems, parental care, and human uses like…

Maxilla (upper jaw bone) Maxilla The maxilla is the paired upper jaw bone that forms the central face, supports the upper teeth, helps form the nose and eye sockets, and varies in form and mobility across vertebra…

Mayfly (Order Ephemeroptera): life cycle, features, and ecological importance Mayfly Mayflies (order Ephemeroptera) are ancient, short-lived aquatic insects. Their aquatic nymphs and brief-winged adults play key roles in freshwater food webs and serve as indicators…

Mecoptera: scorpionflies, hangingflies, and related long-rostrum insects Mecoptera Mecoptera is an order of about 550 species of insects (nine families) including scorpionflies and hangingflies. This article covers their traits, life cycle, behavior, evolution, a…

Medulla oblongata: structure, functions, and clinical importance Medulla oblongata The medulla oblongata is the lowermost brainstem segment that links brain and spinal cord and houses vital centers controlling breathing, circulation and reflexes.

Medusa (biology): the umbrella-shaped form of cnidarians Medusa (biology) A medusa is the free-swimming, umbrella-shaped body form found in many cnidarians. This article explains its anatomy, life cycle, ecological role, dangers to humans, and how it dif…

Megavirus (Megavirus chilensis) — a giant double‑stranded DNA virus Megavirus Megavirus chilensis is a member of the giant viruses infecting free‑living amoebae. It is closely related to Mimivirus and was, until 2013, notable for the largest known capsid and…

Meiosis: reduction division, stages, and role in sexual reproduction Meiosis Meiosis is a specialized cell division that halves chromosome number to produce gametes, creating genetic diversity through recombination and independent assortment and enabling se…