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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Glossary of biology | 4/11 | https://en.wikipedia.org/wiki/Glossary_of_biology | reference | science, encyclopedia | 2026-05-05T07:50:34.867189+00:00 | kb-cron |
deciduous Deciduous means "falling off at maturity" or "tending to fall off", and it is typically used in botany in order to refer to trees or shrubs that lose their leaves seasonally (most commonly during autumn) and to the shedding of other plant structures such as petals after flowering or fruits when ripe.
decomposition The process by which the organic compounds of deceased organisms are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars, and mineral salts. These reactions occur naturally by both biotic means (biodegradation, such as that practiced by many bacteria and fungi) and abiotic means (basic physical and chemical processes, such as hydrolysis). Decomposition recycles matter present in the biosphere, making it an essential part of the nutrient cycle. Organisms that facilitate decomposition are known as decomposers; the scientific study of decomposition is known as taphonomy.
decomposer Any organism that facilitates the breakdown of dead or decaying organisms by carrying out the decomposition of complex biomolecules into simpler substances. Decomposers are heterotrophs which obtain energy and nutrition for their own growth and reproduction by recycling the chemical compounds contained in organic substrates. Microorganisms such as bacteria and fungi are the biosphere's chief decomposers, but invertebrates such as earthworms are also sometimes considered decomposers.
dehydration reaction A chemical reaction that involves the loss of a water molecule from the reacting molecule.
denaturation A process in which proteins or nucleic acids lose the quaternary, tertiary, and secondary structure which is present in their native state, when exposed to some external stress or chemical compound such as a strong acid or base, a concentrated inorganic salt, or an organic solvent.
dendrite A short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.
denitrification The microbially facilitated process of nitrate reduction that ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. It is performed by a large group of heterotrophic facultative anaerobic bacteria and is a fundamental component of the nitrogen cycle.
deoxyribonucleic acid (DNA) A nucleic acid polymer that serves as the fundamental hereditary material in all living organisms. Each DNA molecule is composed of long sequences of nucleotides, each of which includes one of four nitrogenous bases – adenine (abbreviated A), cytosine (C), guanine (G), and thymine (T) – attached to a sugar-phosphate complex which acts as a "backbone" for the long-chain polymer. DNA most commonly occurs in "double-stranded" form, i.e. as a pair of nucleotide polymers bound together by complementary base pairing.
depolarization The process of reversing the charge across a cell membrane (such as that of a neuron), thereby causing an action potential. In depolarization, the inside of the membrane, which is normally negatively charged, becomes positive and the outside becomes negative. This is brought about by positively charged sodium ions rapidly passing into the axon.
desmosome Also called the macula adhaerens. A cell structure specialized for cell-to-cell adhesion.
developmental biology The branch of biology that studies the processes by which living organisms grow and develop over time. The field may also encompass the study of reproduction, regeneration, metamorphosis, and the growth and differentiation of stem cells in mature tissues.
disease Any particular abnormal condition that negatively affects the structure or function of all or part of a living organism and that is not the result of any immediate external injury. Diseases are medical conditions that are often identifiable by specific signs and symptoms. They may be caused by external factors such as infectious pathogens or by internal dysfunctions such as immune deficiency or senescence.
DNA See deoxyribonucleic acid.
DNA replication The chemical duplication or copying of a DNA molecule; the process of producing two identical copies from one original DNA molecule, in which the double helix is unwound and each strand acts as a template for the next strand. Complementary nucleotide bases are matched to synthesize the new partner strands.
DNA sequencing The process of determining the precise order of nucleotides within a DNA molecule.
drug Any substance that causes a change in an organism's physiology or psychology when consumed. Drugs may be naturally occurring or artificially produced, and consumption may occur in a number of different ways. Drugs are typically distinguished from substances that provide nutritional support such as food.
dimorphism The existence of a morphological distinction between organisms of the same species, such that individuals of that species occur in one of two distinct forms which differ in one or more characteristics, such as colour, size, shape, or any other phenotypic trait. Dimorphism based on sex – e.g. male vs. female – is common in sexually reproducing organisms such as plants and animals.
dynein A motor protein in cells which converts the chemical energy contained in ATP into the mechanical energy of movement.
== E ==
ecological efficiency The efficiency with which energy is transferred from one trophic level to the next. It is determined by a combination of efficiencies relating to organismic resource acquisition and assimilation in an ecosystem.
ecological pyramid Also called a trophic pyramid, eltonian pyramid, energy pyramid, or sometimes food pyramid. A graphical representation of the biomass or bio-productivity generated at each trophic level in a given ecosystem.
ecological succession The more or less predictable and orderly set of changes that occurs in the composition or structure of an ecological community over time.
ecology The scientific analysis and study of interactions between organisms and their environment. It is an interdisciplinary field that combines concepts from biology, geography, and Earth science.
ecophysiology A biological discipline that studies the adaptation of an organism's physiology to environmental conditions.
ecosystem A community of living organisms in conjunction with the non-living components of their physical environment, interacting as a system.
ecotype Sometimes called an ecospecies. In evolutionary ecology, a genetically distinct geographic variety, population, or race within a species which is adapted to specific environmental conditions.