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Biology LibreTexts

25.19: Glossary: B

  • Page ID
  • baby boom

    period marked by a temporary but dramatic increase in the birth rate


    one of two domains of prokaryotes, some of which cause human diseases


    ability to sense and maintain an appropriate body position

    bariatric surgery

    weight-loss surgery for obesity that modifies the digestive system to limit the intake of food and/or absorption of nutrients from food

    barrier method

    type of contraception in which a device such as a condom or diaphragm is used to physically block sperm from entering the uterus

    basal cell carcinoma

    most common type of skin cancer that occurs in basal cells of the epidermis and rarely metastasizes

    basal metabolic rate (BMR)

    amount of energy needed to keep the body functioning at rest


    solution with a pH higher than 7

    B cell

    type of lymphocyte that fights infections by forming antibodies

    Bergmann’s rule

    ecogeographic rule stating that, within a broadly distributed taxonomic group, populations or species of larger size are found in colder environments, whereas populations or species of smaller size are found in warmer environments


    fluid produced by the liver and stored in the gall bladder that is secreted into the small intestine to help digest lipids and neutralize acid from the stomach


    brown pigment secreted into bile by the liver that is a byproduct of catabolism of dead red blood cells and is excreted in feces by the large intestine

    binding site

    region of a protein responsible for binding with another molecule

    binge eating disorder

    eating disorder in which people repeatedly binge on a large amount of food, followed by feelings of guilt but not purging and usually leading to excessive weight gain

    binomial nomenclature

    method of naming species with two names, consisting of the genus name and species name


    increasing concentration of a nonbiodegradable substance as it passes from lower to higher trophic levels in an ecosystem

    biochemical compound

    any carbon-based chemical compound that helps make up the cells of living things or carry out life processes

    biochemical reaction

    chemical reaction that occurs inside living things


    referring to a substance such as a pollutant that breaks down in the environment due to natural processes


    all of the variety of life that exists on Earth, including the diversity of genes, species, and ecosystems

    biodiversity hotspot

    area with a high level of biodiversity that is under serious threat from human actions

    biogeochemical cycle

    interconnected pathways through which water or a chemical element such as carbon or nitrogen is continuously recycled through the biotic and abiotic components of ecosystems


    study of how and why organisms live where they do


    amount of organic matter present in an individual organism or in all the organisms at a given trophic level

    biomass energy

    energy obtained from living or recently living things, such as wood or biogas made from crops such as sugarcane


    group of similar ecosystems with the same general type of physical environment anywhere in the world


    surgical removal of a tissue specimen for analysis in a medical laboratory, usually to diagnose cancer


    every part of Earth where life exists, including land, water, and air


    use of technology to change the genetic makeup of living things in order to produce useful products

    biotic factor

    living aspect of the environment, including any organism of the same or different species


    walking on two legs

    birth rate

    number of births in one year per 1,000 people in a population


    weight of a baby at birth

    Black Death

    mid-14th century Eurasian plague pandemic that was one of the deadliest pandemics in human history

    bladder infection

    common type of urinary tract infection in which the bladder becomes infected, usually by bacteria but occasionally by fungi


    fluid-filled cavity within a blastocyst


    fluid-filled ball of cells that develops a few days after fertilization in the process of blastulation


    process during the germinal stage in which the solid ball of cells called the morula changes into a fluid-filled ball of cells called the blastocyst

    blind experiment

    scientific experiment in which subjects do not know in which experimental group they have been placed to help avoid bias in the outcome


    fluid connective tissue that circulates throughout the body through blood vessels

    blood-brain barrier

    highly selective membrane formed of epithelial cells that separates circulating blood from extracellular fluid in the brain and spinal cord

    blood group system

    all of the genes, alleles, and possible genotypes and phenotypes that exist for a particular set of blood type antigens

    blood pressure

    measure of the force exerted by circulating blood on the walls of arteries

    blood type

    genetic characteristic associated with the presence or absence of antigens on the surface of red blood cells

    blood vessel

    hollow, tube-like structure through which blood flows in the cardiovascular system; vein, artery, or capillary

    body cavity

    fluid-filled space inside the body that holds and protects internal organs

    body mass index (BMI)

    estimate of the fat content of the body that is calculated by dividing a person’s weight (in kilograms) by the square of the person’s height (in meters)


    lump of swallowed food

    bone marrow

    soft connective tissue in spongy bone that produces blood cells

    bone remodeling

    continuous, lifelong process in which existing bone is resorbed by osteoclasts and new bone is made by osteoblasts

    bone repair

    process in which bone heals itself following a bone fracture

    bone tissue

    hard connective tissue in bones that consists mainly of mineralized collagen matrix; also called osseous tissue

    Bowman’s capsule

    structure surrounding the glomerulus of a nephron in a kidney into which substances that are filtered out of blood are passed to the renal tubule


    central nervous system organ inside the skull that is the control center of the nervous system

    brain stem

    lowest part of the brain that connects the brain with the spinal cord and controls unconscious functions such as heart rate and breathing

    Broca’s area

    speech center in the brain that controls speech production

    bronchus (plural, bronchi)

    one of many tubes of various sizes that carry air between the trachea and the alveoli in the lungs

    bulbourethral gland

    one of a pair of glands in the male reproductive system that secretes a fluid to help lubricate the urethra and neutralize any urine it may contain before ejaculation occurs; also called Cowper’s gland

    bulimia nervosa

    eating disorder in which people recurrently binge on large amounts of food, following by purging the food from the body, for example, by vomiting