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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 that prevents water and oxygen from reaching and activating the embryo. It is a physical barrier to germination, not a true form of dormancy (Quinliven, 1971; Quinliven and Nichol ...
True dormancy or inherent (or innate) dormancy is caused by conditions within the seed that prevent germination even if the conditions are favorable. [7] Imposed dormancy is caused by the external conditions that remain unsuitable for germination [8] Seed dormancy can be divided into two major categories based on what part of the seed produces dormancy: exogenous and endogenous. [9]
Disseminating cancer cells can proliferate or become dormant depending on the microenvironment and factors such as the ERK/p38 ratio. Dormancy is a stage in cancer progression where the cells cease dividing but survive in a quiescent state while waiting for appropriate environmental conditions to begin proliferation again. [1]
Four degrees Celsius is cool enough to end dormancy for most cool dormant seeds, but some groups, especially within the family Ranunculaceae and others, need conditions cooler than -5 C. Some seeds will only germinate after hot temperatures during a forest fire which cracks their seed coats; this is a type of physical dormancy.
Exogenous dormancy is caused by conditions outside the embryo, including: Physical dormancy or hard seed coats occurs when seeds are impermeable to water. At dormancy break, a specialized structure, the 'water gap', is disrupted in response to environmental cues, especially temperature, so water can enter the seed and germination can occur.
Aestivation (Latin: aestas (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. [ 1 ]
Persister cells are subpopulations of cells that resist treatment, and become antimicrobial tolerant by changing to a state of dormancy or quiescence. [1] [2] Persister cells in their dormancy do not divide. [3] The tolerance shown in persister cells differs from antimicrobial resistance in that the tolerance is not inherited and is reversible. [4]
Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate.Torpor enables animals to survive periods of reduced food availability. [1]