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Dormancy is a period in an
organism's
organism's
life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis, ...
when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes
metabolic activity Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life Life is a characteristic that distinguishes physical entities that have biological processes, such as signaling and self-sustaining processes, ...

metabolic activity
and therefore helps an organism to conserve
energy In physics, energy is the physical quantity, quantitative physical property, property that must be #Energy transfer, transferred to a physical body, body or physical system to perform Work (thermodynamics), work on the body, or to heat it. En ...

energy
. Dormancy tends to be closely associated with
environmental conditions
environmental conditions
. Organisms can synchronize entry to a dormant phase with their
environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

environment
through predictive or consequential means. Predictive dormancy occurs when an organism enters a dormant phase ''before'' the onset of adverse conditions. For example,
photoperiodPhotoperiodism is the physiological reaction of organisms to the length of night or a dark period. It occurs in plants and animals. Photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark ...
and decreasing
temperature Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat, a flow of energy, when a body is in contact with another that is ...

temperature
are used by many
plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions o ...

plant
s to predict the onset of winter. Consequential dormancy occurs when organisms enter a dormant phase ''after'' adverse conditions have arisen. This is commonly found in areas with an unpredictable climate. While very sudden changes in conditions may lead to a high
mortality rate Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular Statistical population, population, scaled to the size of that population, per unit of time. Mortality rate is typically e ...
among animals relying on consequential dormancy, its use can be advantageous, as organisms remain active longer and are therefore able to make greater use of available resources.


Animals


Hibernation

Hibernation is a mechanism used by many mammals to reduce energy expenditure and survive food shortages over the winter. Hibernation may be predictive or consequential. An animal prepares for hibernation by building up a thick layer of
body fat Adipose tissue, body fat, or simply fat is a loose connective tissue Connective tissue is one of the four basic types of animal tissue (biology), tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesod ...
during late summer and autumn that will provide it with energy during the dormant period. During hibernation, the animal undergoes many
physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, B ...
changes, including decreased
heart rateHeart rate is the speed of the heartbeat measured by the number of contractions (beats) of the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory syste ...

heart rate
(by as much as 95%) and decreased
body temperature Thermoregulation is the ability of an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It is a sy ...
. In addition to shivering, some hibernating animals also produce body heat by non-shivering thermogenesis to avoid freezing. Non-shivering thermogenesis is a regulated process in which the proton gradient generated by electron transport in mitochondria is used to produce heat instead of ATP in brown adipose tissue. Animals that hibernate include
bats Bats are mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of mammary glands which in Female#Mammalian femal ...
,
ground squirrel The ground squirrels are members of the squirrel family of rodents (Sciuridae), which generally live on or in the ground, rather than trees. The term is most often used for the medium-sized ground squirrels, as the larger ones are more commonly kno ...

ground squirrel
s and other rodents, mouse lemurs, the
European hedgehog The European hedgehog (''Erinaceus europaeus''), also known as the West European hedgehog or common hedgehog, is a hedgehog species native to Europe from Iberia and Italy northwards into Scandinavia and westwards into the British Isles.Harris, S. ...
and other insectivores, monotremes and marsupials. Although hibernation is almost exclusively seen in mammals, some birds, such as the
common poorwill The common poorwill (''Phalaenoptilus nuttallii'') is a nocturnal bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves , characterised by feathers, toothless beaked jaws, the Oviparity, laying o ...
, may hibernate.


Diapause

Diapause is a predictive strategy that is predetermined by an animal's
genotype The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is one of two, or more, forms of a given gene ...
. Diapause is common in
insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, Thorax (inse ...

insect
s, allowing them to suspend development between autumn and spring, and in
mammals Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the R ...
such as the
roe deer The roe deer (''Capreolus capreolus''), also known as the roe, western roe deer, or European roe, is a species of deer Deer or true deer are hoofed ruminant Ruminants are herbivorous mammals of the suborder Ruminantia that are able to acq ...

roe deer
(''Capreolus capreolus'', the only
ungulate Ungulates ( ) are members of the diverse clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic—that is, composed of a common ances ...
with
embryonic diapause Embryonic diapause (from late 19th century English: dia- ‘through’ + pause- 'delay') (aka delayed implantation) is a Reproduction, reproductive strategy used by approximately 100 different mammals in seven or eight different order (biology), ord ...
), in which a delay in attachment of the
embryo An embryo is the early stage of development of a multicellular organism. In general, in organisms that Sexual reproduction, reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization and continue ...

embryo
to the
uterine The uterus (from Latin "uterus", plural ''uteri'') or womb () is a major female hormone-responsive sex organ, secondary sex organ of the reproductive system in humans and most other mammals. Things occurring in the uterus are described with the ...

uterine
lining ensures that
offspring In biology, offspring are the young born of living organism, organisms, produced either by a single organism or, in the case of sexual reproduction, two organisms. Collective offspring may be known as a brood or progeny in a more general way. Thi ...

offspring
are born in spring, when conditions are most favorable.


Aestivation

Aestivation, also spelled ''estivation'', is an example of consequential dormancy in response to very hot or dry conditions. It is common in
invertebrates Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all animals apart from the chordata, chordate subphylum vertebrate, Vertebrat ...
such as the garden snail and
worm Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limb Limb can refer to: *Limb (anatomy), an appendage of a human or animal *Limb Music, a record label *Limb (album), an a ...

worm
but also occurs in other animals such as
lungfish Lungfish are freshwater rhipidistian vertebrates belonging to the Order (taxonomic rank), order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral ...
,
salamanders Salamanders are a group of amphibian Amphibians are ectothermic, tetrapod Tetrapods (; from Greek 'four' and 'foot') are four-limbed animals constituting the superclass Tetrapoda . It includes extant and extinct amphibians, rept ...
,
desert tortoise The desert tortoise (''Gopherus agassizii)'', is a species of tortoise in the Family (biology), family Testudinidae. The species is native to the Mojave Desert, Mojave and Sonoran Deserts of the southwestern United States and northwestern Mexico, ...

desert tortoise
s, and
crocodiles Crocodiles (subfamily Crocodylinae) or true crocodiles are large list of semiaquatic tetrapods, semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodylinae, all of whose members are considere ...
.


Brumation

While
endotherm An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inste ...
s and other
heterotherm Heterothermy or heterothermia (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approx ...
s are described scientifically as
hibernating
hibernating
, the way
ectotherm File:Junonia lemonias DSF by Kadavoor.JPG, ''Junonia lemonias'' is basking under the sun. An ectotherm (from the Ancient Greek, Greek ἐκτός (''ektós'') "outside" and θερμός (''thermós'') "hot") is an organism in which internal physio ...
s such as lizards become dormant in cold is very different, and a separate name was invented for it in the 1920s:
brumation Dormancy is a period in an organism's life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the pr ...
. It differs from hibernation in the metabolic processes involved. Reptiles generally begin brumation in late autumn (more specific times depend on the species). They often wake up to drink water and return to "sleep". They can go for months without food. Reptiles may eat more than usual before the brumation time but eat less or refuse food as the temperature drops. However, they do need to drink water. The brumation period is anywhere from one to eight months depending on the air temperature and the size, age, and health of the reptile. During the first year of life, many small reptiles do not fully brumate, but rather slow down and eat less often. Brumation is triggered by a lack of heat and a decrease in the hours of daylight in winter, similar to hibernation.


Plants

In
plant physiology Plant physiology is a subdiscipline of botany Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds ...

plant physiology
, dormancy is a period of arrested plant growth. It is a survival strategy exhibited by many plant
species In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanis ...

species
, which enables them to survive in
climate Climate is the long-term average of weather, typically averaged over a period of 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...

climate
s where part of the year is unsuitable for growth, such as winter or
dry season The dry season is a yearly period of low rainfall, especially in the tropics The tropics are the region of Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's su ...
s. Many plant species that exhibit dormancy have a
biological clock
biological clock
that tells them when to slow activity and to prepare
soft tissues of a tendon A tendon or sinew is a tough band of fibrous connective tissue that connects muscle to bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate skeleton in animals. Bones protect the var ...
for a period of freezing temperatures or water shortage. On the other hand, dormancy can be triggered after a normal growing season by decreasing temperatures, shortened day length, and/or a reduction in
rainfall Rain is liquid water in the form of droplet Raindrops in a plant. A drop or droplet is a small column of liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformation (mechani ...

rainfall
. Chemical treatment on dormant plants has been proven to be an effective method to break dormancy, particularly in woody plants such as grapes, berries, apples, peaches, and kiwis. Specifically, hydrogen cyanamide stimulates cell division and growth in dormant plants, causing buds to break when the plant is on the edge of breaking dormancy. Slight injury of cells may play a role in the mechanism of action. The injury is thought to result in increased permeability of cellular membranes. The injury is associated with the inhibition of catalase, which in turn stimulates the pentose phosphate cycle. Hydrogen cyanamide interacts with the cytokinin metabolic cycle, which results in triggering a new growth cycle. The images below show two particularly widespread dormancy patterns amongst
sympodial Sympodial growth is type of bifurcating branching pattern where one branch develops more strongly than the other, resulting in the stronger branches forming the primary shoot and the weaker branches appearing laterally. A sympodium, also referred ...
ly growing orchids:


Seeds

When a mature and viable
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positiv ...

seed
under a favorable condition fails to germinate, it is said to be dormant.
Seed dormancy Seed dormancy is an evolutionary adaptation that prevents seeds from germinating during unsuitable ecological conditions that would typically lead to a low probability of seedling survival. Dormant seeds A seed is an Plant embryogenesis, embry ...
is referred to as embryo dormancy or internal dormancy and is caused by endogenous characteristics of the embryo that prevent
germination seedlings, three days after germination Germination is the process by which an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell t ...

germination
(Black M, Butler J, Hughes M. 1987). Dormancy should not be confused with seed coat dormancy, external dormancy, or hardheadedness, which is caused by the presence of a hard seed covering or
seed coat A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positiv ...
that prevents water and oxygen from reaching and activating the
embryo An embryo is the early stage of development of a multicellular organism. In general, in organisms that Sexual reproduction, reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization and continue ...

embryo
. It is a physical barrier to germination, not a true form of dormancy (Quinliven, 1971; Quinliven and Nichol, 1971). Seed dormancy is desired in nature, but the opposite in the agriculture field. This is because agricultural practice desires rapid germination and growth for food whereas in nature, most plants are only capable of germinating once every year, making it favorable for plants to pick a specific time to reproduce. For many plants, it is preferable to reproduce in spring as opposed to fall even when there are similar conditions in terms of light and temperature due to the ensuing winter that follows fall. Many plants and seeds recognize this and enter a dormant period in the fall to stop growing. The grain is a popular example in this aspect, where they would die above ground during the winter, so dormancy is favorable to its seedlings but extensive domestication and crossbreeding has removed most dormancy mechanisms that their ancestors had. While seed dormancy is linked to many genes, abscisic acid (ABA), a plant hormone, has been linked as a major influencer to seed dormancy. In a study on rice and tobacco plants, plants defective in zeaxanthin epoxidase gene, which are linked to ABA-synthesis pathway. Seeds with higher ABA content, from over-expressing zeaxanthin epoxidase, led to an increased dormancy period while plants with lower numbers of zeaxanthin epoxidase were shown to have a shorter period of dormancy. A simple diagram can be drawn of ABA inhibits seed germination, while gibberellin (GA, also plant hormone) inhibits ABA production and promotes seed germination.


Trees

Typically, temperate woody
perennial plant A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and incl ...
s require chilling temperatures to overcome winter dormancy (rest). The effect of chilling temperatures depends on species and growth stage (Fuchigami et al. 1987).Fuchigami, L. H., Nee, C. C., Tanino, K., Chen, T. H. H., Gusta, L. V., and Weiser, C. J. 1987. "Woody Plant Growth in a Changing Chemical and Physical Environment". Proc. Workshop IUFRO Working Party on Shoot Growth Physiology, Vancouver, British Columbia, July 1987, Lavender, D. P. (Compiler & Ed.), University of British Columbia, Forest Science Department, Vancouver, British : 265–282. In some species, rest can be broken within hours at any stage of dormancy, with either chemicals, heat, or freezing temperatures, effective dosages of which would seem to be a function of sublethal stress, which results in stimulation of
ethylene Ethylene (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Science Co ...

ethylene
production and increased cell membrane permeability. ''Dormancy'' is a general term applicable to any instance in which a tissue predisposed to elongate or grow in some other manner does not do so (Nienstaedt 1966). ''Quiescence'' is dormancy imposed by the external environment. ''Correlated inhibition'' is a kind of physiological dormancy maintained by agents or conditions originating within the plant, but not within the dormant tissue itself. ''Rest'' (winter dormancy) is a kind of physiological dormancy maintained by agents or conditions within the organ itself. However, physiological subdivisions of dormancy do not coincide with the morphological dormancy found in white spruce (''Picea glauca'') and other
conifers Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All exta ...

conifers
(Owens et al. 1977). Physiological dormancy often includes early stages of bud-scale initiation before measurable shoot elongation or before flushing. It may also include late leaf initiation after shoot elongation has been completed. In either of those cases,
bud In botany Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes k ...

bud
s that appear to be dormant are nevertheless very active morphologically and physiologically. Dormancy of various kinds is expressed in white spruce (Romberger 1963).Romberger, J. A. 1963. "Meristems, Growth, and Development in Woody Plants". USDA, Forestry Service, Washington DC, Technical Bulletin 1293. 214 p. White spruce, like many woody plants in temperate and cooler regions, requires exposure to low temperature for a period of weeks before it can resume normal growth and development. This "chilling requirement" for white spruce is satisfied by uninterrupted exposure to temperatures below 7 °C for 4 to 8 weeks, depending on physiological condition (Nienstaedt 1966, 1967). Tree species that have well-developed dormancy needs may be tricked to some degree, but not completely. For instance, if a
Japanese maple ''Acer palmatum'', commonly known as Japanese maple, palmate maple, or smooth Japanese maple (Japanese: ''irohamomiji'', , or ''momiji'', ), is a species of woody plant native to Japan , image_flag = Flag of Japan.svg , ...

Japanese maple
(''Acer palmatum'') is given an "eternal summer" through exposure to additional daylight, it grows continuously for as long as two years. Eventually, however, a temperate-climate plant automatically goes dormant, no matter what environmental conditions it experiences.
Deciduous In the fields of horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticulturists grow flowers, fruits and nuts, vegetables and herbs, as we ...
plants lose their leaves;
evergreen In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Anci ...

evergreen
s curtail all new growth. Going through an "eternal summer" and the resultant automatic dormancy is stressful to the plant and usually fatal. The fatality rate increases to 100% if the plant does not receive the necessary period of cold temperatures required to break the dormancy. Most plants require a certain number of hours of "chilling" at temperatures between about 0 °C and 10 °C to be able to break dormancy (Bewley, Black, K.D 1994). Short photoperiods induce dormancy and permit the formation of needle primordia. Primordia formation requires 8 to 10 weeks and must be followed by 6 weeks of chilling at 2 °C. Bud break occurs promptly if seedlings are then exposed to 16-hour photoperiods at the 25 °C/20 °C temperature regime. The free growth mode, a juvenile characteristic that is lost after 5 years or so, ceases in seedlings experiencing environmental stress (Logan and Pollard 1976, Logan 1977).Logan, K. T.; Pollard, D. F. W. 1976. "Growth acceleration of tree seedlings in controlled environments at Petawawa". Canadian Forestry Service, Petawawa Forest Experiment Station, Chalk River, Ontario, Information PS-X-62.


Bacteria

Many
bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a Bacte ...

bacteria
can survive adverse conditions such as temperature,
desiccation in sludge Moenave Formation at the St. George Dinosaur Discovery Site at Johnson Farm, southwestern Utah. A dinosaur footprint is at center. Desiccation (from Latin de- "thoroughly" + siccare "to dry") is the state of extreme dryness, or the ...
, and
antibiotic An antibiotic is a type of antimicrobial An antimicrobial is an agent that kills microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμ ...
s by forming
endospore An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), dom ...
s,
cyst A cyst is a closed sac, having a distinct envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac (like the manner in which w ...
s, or states of reduced metabolic activity lacking specialized cellular structures. Up to 80% of the bacteria in samples from the wild appear to be metabolically inactive—many of which can be resuscitated. Such dormancy is responsible for the high diversity levels of most natural ecosystems. Recent research has characterized the bacterial
cytoplasm In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, ...
as a glass forming fluid approaching the liquid-glass transition, such that large cytoplasmic components require the aid of
metabolic activity Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life Life is a characteristic that distinguishes physical entities that have biological processes, such as signaling and self-sustaining processes, ...
to fluidize the surrounding cytoplasm, allowing them to move through a viscous, glass-like cytoplasm. During dormancy, when such metabolic activities are put on hold, the cytoplasm behaves like a solid
glass Glass is a non- crystalline, often transparency and translucency, transparent amorphous solid, that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by ...

glass
, 'freezing' subcellular structures in place and perhaps protecting them, while allowing small molecules like
metabolites In biochemistry, a metabolite is an intermediate or end product of metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main purposes of metabo ...

metabolites
to move freely through the cell, which may be helpful in cells transitioning out of dormancy.


Viruses

Dormancy in its rigid definition does not apply to
virus A virus is a submicroscopic infectious agent that Viral replication, replicates only inside the living Cell (biology), cells of an organism. Viruses infect all types of life forms, from animals and plants to microorganisms, including bacte ...

virus
es, as they are not metabolically active. However, some viruses such as
poxvirus ''Poxviridae'' is a family of viruses. Humans, vertebrates, and arthropods serve as natural hosts. There are currently 83 species in this family, divided among 22 genera, which are divided into two subfamilies. Diseases associated with this family ...
es and
picornavirus Picornaviruses are a group of related Viral envelope, nonenveloped RNA viruses which infect vertebrates including mammals and birds. They are viruses that represent a large family of small, Positive-sense single-stranded RNA virus, positive-sense ...

picornavirus
es after entering the host can become latent for long periods of time, or even indefinitely until they are externally activated.
Herpesvirus ''Herpesviridae'' is a large family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of families is to mai ...

Herpesvirus
es for example can become latent after infecting the host and after years activate again if the host is under stress or exposed to ultraviolet radiation.


See also

*
Plant physiology Plant physiology is a subdiscipline of botany Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds ...

Plant physiology
*
Scotobiology Scotobiology is the study of biology as directly and specifically affected by darkness, as opposed to photobiology, which describes the biological effects of light. Overview The science of scotobiology gathers together under a single descriptive h ...
*
Torpor Torpor is a state of decreased physiological activity in an animal, usually by a reduced body temperature Thermoregulation is the ability of an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''orga ...


Notes


References

* Bewley, J. D. and Black, M. (1994). ''Seeds: physiology of development and germination, 2nd end''. New York, London: Plenum Press. * Black, M.; Butler, J. and Hughes, M. (1987). "Control and development of dormancy in cereals". In: Mares DJ, ed. ''Fourth International Symposium on Pre-Harvest Sprouting in Cereals'', Boulder, Co., USA: Westview Press, 379–92. * * {{cite journal , last1 = Quinlivan , first1 = B. J. , year = 1971 , title = Seed coat impermeability in legumes , journal = Journal of the Australian Institute of Agricultural Science , volume = 37 , pages = 283–295 * Scholar team. (2002). "SQA Adv. Higher Biology". ''Environmental Biology''. Heriot-Watt University, 93–95. Plant physiology Physiology Ethology