Category: Dictionary

Phytopathology : The science of diagnosing and managing plant diseases.

Phytochemistry : The study of phytochemicals, which are chemicals derived from plants.

Physiology : The branch of biology dealing with the functions and activities of living organisms and their parts, including all physical and chemical processes.

Phylum : A taxonomic rank or level of classification below kingdom and above class; in botany, the term division is commonly used in place of phylum.

Photosynthesis : The process by which nearly all plants and some algae and bacteria convert the energy of sunlight into chemical energy, which is used to synthesize carbohydrates such as sugars from carbon dioxide and water; these carbohydrates are stored as food, and the energy within them is later released to fuel metabolic activities. Organisms that perform photosynthesis are therefore autotrophs. Photosynthesis supplies the majority of the energy necessary for life on Earth.

Pheromone : A secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are analogous to hormones acting outside the body of the secreting individual to impact the behavior of receiving individuals.

Phenotype : The composite of an organism’s observable features or traits, such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior.

Pharmacology : The science of drug action on biological systems. In its entirety, it embraces knowledge of the sources, chemical properties, biological effects, and therapeutic uses of drugs.

pH : A numeric scale used to specify the acidity or basicity (alkalinity) of an aqueous solution. It is roughly the negative of the logarithm to base 10 of the concentration, measured in units of moles per liter, of hydrogen ions.

Pathology : A medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids such as blood and urine, as well as tissues, using the tools of chemistry, clinical microbiology, hematology, and molecular pathology.

Pathogen : In the broadest sense, anything that can produce disease, though the term is most commonly used to refer specifically to an infectious microscopic organism such as a virus, bacterium, protozoan, or another microbial agent which causes disease for a host organism by invading the host’s tissues.

Pathobiology : The study or practice of pathology with greater emphasis on the biological than on the medical aspects.

Parasitology : The study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question, but by their way of life.

Paleontology : The study of the history of life on Earth as reflected in the fossil record. Fossils are the remains or traces of organisms that lived in the geological past and have been preserved in the Earth’s crust.

Osmosis: The spontaneous net movement of solvent molecules through a semipermeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.

Ornithology : The branch of zoology that concerns the study of birds.

Organism : A contiguous living system.

 Organ : A collection of tissues joined in a structural unit to serve a common function.

Nucleotide : An organic compound which serves as the fundamental monomer used in the construction of nucleic acid polymers, such as DNA and RNA, both of which are essential biomolecules within all living organisms.

Nucleolus : The largest structure within the nucleus of eukaryotic cells.

Nucleoid : An irregularly shaped region within the cell of a prokaryote that contains all or most of the genetic material, called the genophore.

Nucleobase : The nitrogen-containing biological compounds that form nucleosides, which in turn are components of nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids.

Nucleic acid sequence : A succession of letters that indicate the order of nucleotides forming alleles within a DNA or RNA molecule.

Nucleic acid : The biopolymers, or small biomolecules, essential to all known forms of life .

Niche : The role and position an organism or taxon fills within its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces. A species’ niche includes all of its interactions with the biotic and abiotic factors of its environment.

Neurotransmitter : An endogenous compound that enable neurotransmission.

Neuron : An electrically excitable cell that receives, processes, and transmits information through electrical and chemical signals.

Neurobiology : Also called neuroscience.

The scientific study of the nervous system.

Natural selection : A process in nature in which organisms possessing certain genotypic characteristics that make them better adjusted to an environment tend to survive, reproduce, increase in number or frequency, and therefore, are able to transmit and perpetuate their essential genotypic qualities to succeeding generations.

Myosin : A superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes.

Myofibril : A basic rod-like unit of a muscle cell.

Mycology : The branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicine, food, and entheogens, as well as their dangers, such as poisoning or infection.

Multicellular : Having or consisting of more than one cell, as opposed to being unicellular.

Mucous membrane : A membrane that lines various cavities in the body and covers the surface of internal organs.

Motor neuron: A neuron whose cell body is situated in the motor cortex, brain stem, or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands.

Monomer : A molecule that “can undergo polymerization thereby contributing constitutional units to the essential structure of a macromolecule”.

Molecular switch : A molecule that can be reversibly changed between two or more stable states.

Molecular biology : The branch of biology concerning biological activity at the molecular level. The field of molecular biology overlaps with biology and chemistry and in particular with genetics and biochemistry.

Molecule : The smallest particle in a chemical element or compound that has the chemical properties of that element or compound. Molecules are made up of atoms that are held together by chemical bonds. These bonds form as a result of the sharing or exchange of electrons among atoms.

Mitosis : In eukaryotic cells, the part of the cell cycle during which the division of the nucleus takes place and duplicated chromosomes are separated into two distinct nuclei. Mitosis is generally preceded by the “S” stage of interphase, when the cell’s DNA is replicated, and followed by cytokinesis, when the cytoplasm and cell membrane are divided into two new daughter cells. It is similar to but distinct from binary fission and meiosis.

Mitochondria : (sing.) mitochondrion

Microevolution : The alteration in allele frequencies that occurs over time within a population.

Microbiology : The study of microscopic organisms, such as bacteria, viruses, archaea, fungi and protozoa. This discipline includes fundamental research on the biochemistry, physiology, cell biology, ecology, evolution and clinical aspects of microorganisms, including the host response to these agents.

Metaphase : The third phase of mitosis, in which duplicated genetic material carried in the nucleus of a parent cell is separated into two identical daughter cells. During metaphase, the cell’s chromosomes align themselves in the middle of the cell through a type of cellular “tug of war”.

Messenger RNA : A large family of RNA molecules that convey genetic information from DNA to the ribosome.

Membrane potential : When a nerve or muscle cell is at “rest”, its membrane potential is called the resting membrane potential. In a typical neuron, this is about –70 millivolts (mV). The minus sign indicates that the inside of the cell is negative with respect to the surrounding extracellular fluid.

Meiosis : A specialized type of cell division in which a dividing parent cell proceeds through two consecutive divisions, ultimately producing four genetically unique daughter cells in each of which the chromosome number is half of that in the original parent cell. This process is exclusive to cells of the sex organs in sexually reproducing eukaryotes, where it serves the purpose of generating gametes such as eggs, sperm, or spores.

Medulla : The continuation of the spinal cord within the skull, forming the lowest part of the brainstem and containing control centres for the heart and lungs.

Mast cell : A cell filled with basophil granules, found in numbers in connective tissue and releasing histamine and other substances during inflammatory and allergic reactions.

Marine biology : The study of organisms in the ocean or other marine bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy.

Mammalogy : The branch of biology that studies mammals, a class of vertebrates with characteristics such as homeothermic metabolism, fur, four-chambered hearts, and complex nervous systems.

Macrophage : A kind of swallowing cell, which means it functions by literally swallowing up other particles or smaller cells. Macrophages engulf and digest debris (such as dead cells) and foreign particles through the process of phagocytosis, so macrophages act like scavengers.

Macronutrient : Nutrients needed in large amounts which provide calories or energy. Nutrients are substances needed for growth, metabolism, and for other body functions. There are three basic types of macronutrients: fats, proteins, and carbohydrates.

Macromolecule : A very large molecule, such as a protein, commonly created by polymerization of smaller subunits (monomers). They are typically composed of thousands or more atoms.

Macroevolution : Evolution on a scale of separated gene pools. Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population.

M phase : Mitosis and cytokinesis together define the mitotic (M) phase of an animal cell cycle – the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell.

Lipoprotein : A biochemical assembly that contains both proteins and lipids, bound to the proteins, which allow fats to move through the water inside and outside cells. The proteins serve to emulsify the lipid molecules.

Lipid : A substance that is insoluble in water and soluble in alcohol, ether, and chloroform. Lipids are an important component of living cells. Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells. Cholesterol and triglycerides are lipids.

Linked genes : Any set of one or more genes which are sufficiently close together on the same chromosome that they are very unlikely to assort independently and therefore are usually inherited together.

Light-independent reactions : See Calvin cycle.

Ligament : The fibrous connective tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.

Life : The characteristic or collection of characteristics that distinguishes physical entities that undergo biological processes (e.g. living organisms) from that those do not (e.g. non-living, inanimate matter), either because such processes have ceased or because they were not present in the first place. What constitutes “life” is notoriously difficult to define, and there is currently no consensus definition, though some popular criteria are that living things are composed of cells, have a life cycle, undergo metabolism, maintain homeostasis, adapt to environments, respond to stimuli, reproduce, and evolve. Biology is the scientific study of life and of living organisms.

Leukocyte : Also called a white blood cell.

A colourless cell of the immune system which circulates in the blood and body fluids and is involved in counteracting foreign substances and disease. There are several types of leukocytes, all amoeboid cells with a nucleus, including lymphocytes, granulocytes, and monocytes.

Law of Independent Assortment : The principle, originally formulated by Gregor Mendel, stating that when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together.

Larva : (pl.) larvaeA distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development, such as insects, amphibians, or cnidarians, typically have a larval phase of their life cycle.

Krebs cycle : See citric acid cycle.

Kinase : An enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates.

Tejunum : like gher vertebrates like mammals, birds, and reptiles. It is present between the duodenum and the ileum.

Isotonic solution : Refers to two solutions having the same osmotic pressure across a semipermeable membrane. This state allows for the free movement of water across the membrane without changing the concentration of solutes on either side.

Isomer : A molecule with the same chemical formula as another molecule, but with a different chemical structure. That is, isomers contain the same number of atoms of each element, but have different arrangements of their atoms.

Ionic bond : A type of chemical bond involving the complete transfer of valence electron(s) between two atoms. Such bonds typically occur between elements characterized as metals and nonmetals, and generate two oppositely charged ions: the metal loses electrons to become a positively charged cation, and the nonmetal accepts those electrons to become a negatively charged anion.

Ion : An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

Invertebrate : A group of animals that have no backbone, unlike animals such as reptiles, amphibians, fish, birds, and mammals, which all have a backbone. Among the many extant invertebrate phyla are the Cnidaria, Mollusca, Annelida, Nematoda, and Arthropoda.

Introduced species : Also called an exotic species, foreign species, alien species, non-native species, or non-indigenous species.
Any species living outside its native geographic range, and which has arrived there either by accidental or deliberate human activity. Such human-caused introduction of species to foreign environments is distinguished from biological colonization, by which species spread to new areas through “natural” means (i.e. without the involvement of humans).

Intracellular : Of or occurring inside or within the enclosed interior of a cell. Contrast extracellular.

International System of Units : (French: Système international d’unités; abbreviated SI) The modern standardized form of the metric system of units and measurements, and the system of measurement formally adopted for use in the physical and natural sciences.

Internal fertilization : A type of fertilization which takes place inside the egg-producing individual.

Interferon : A group of signaling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, or tumor cells. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their antiviral defenses.

Integrative biology : The various forms of cross-disciplinary and multitaxon research.

Insulin : An anabolic peptide hormone produced in the pancreas which helps to regulate the metabolism of carbohydrates, fats, and protein by promoting the absorption of glucose from the blood into liver, fat, and skeletal muscle cells. Abnormal insulin activity is the cause of diabetes mellitus.

Infection : The invasion of an organism’s cells or tissues by a disease-causing pathogen, its growth and/or multiplication, and the reaction of the host organism to the infectious agent and the toxins it produces. The variety of biological pathogens capable of causing infections includes certain bacteria, viruses, fungi, protists, parasitic worms, and arthropods.

Immunoglobulin : Any of a class of glycoprotein molecules produced by plasma cells (white blood cells) which act as a critical part of the immune response by specifically recognizing and binding to particular antigens, such as bacteria or viruses, and aiding in their destruction. They are a major component of the group of immune defense molecules collectively called antibodies.

Immune response : The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful.

Ichthyology : The branch of biology devoted to the study of fish, including bony fishes (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha).

Hydrocarbon : An organic compound consisting entirely of hydrogen and carbon atoms. Hydrocarbons from which one hydrogen atom has been removed are functional groups called hydrocarbyls.

Host : Any living organism that harbors another living organism (known as a “guest” or symbiont), whether the guest is parasitic, mutualistic, or commensalist in its interactions with the host. The guest typically receives shelter and nourishment from the host.

Hormone : Any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.

Hodgkin–Huxley model  : A mathematical model that describes how action potentials in neurons are initiated and propagated.

Histology : The study of the microscopic anatomy of cells and tissues of plants and animals.

Heterosis : The improved or increased function of any biological quality in a hybrid offspring.

Herpetology : The branch of zoology that studies reptiles and amphibians.

Hermaphrodite : A sexually reproducing organism with both male and female reproductive organs.

Heredit : The passing on of phenotypic traits from parents to their offspring, either through sexual or asexual reproduction. Offspring cells and organisms are said to inherit the genetic information of their parents.

Habitat : A place for animals, people, and plants and non-living things.

Guanine : One of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA).

Gizzard : An organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, and dinosaurs, including birds), earthworms, some gastropods, some fish, and some crustaceans.

Genotype : Part of the genetic makeup of a cell, and therefore of an organism or individual, which determines one of its characteristics (phenotype).

Genome : The entire set of genetic material contained within the chromosomes of an organism, organelle, or virus.

Genetics : The study of heredity.

Genetic variation : Variations of genomes between members of species, or between groups of species thriving in different parts of the world as a result of genetic mutation. Genetic diversity in a population or species is a result of new gene combinations (e.g. crossing over of chromosomes), genetic mutations, genetic drift, etc.