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The term heterotroph arose in microbiology in 1946 as part of a classification of microorganisms based on their type of nutrition. [6] The term is now used in many fields, such as ecology, in describing the food chain. Heterotrophs occupy the second and third tropic levels of the food chain while autotrophs occupy the first trophic level. [7]
Monotropa uniflora, an obligate myco-heterotroph known to parasitize fungi belonging to the Russulaceae. [1]Myco-heterotrophy (from Greek μύκης mýkes ' fungus ', ἕτερος héteros ' another ', ' different ' and τροφή trophé ' nutrition ') is a symbiotic relationship between certain kinds of plants and fungi, in which the plant gets all or part of its food from parasitism upon ...
Food chain length is another way of describing food webs as a measure of the number of species encountered as energy or nutrients move from the plants to top predators. [ 41 ] : 269 There are different ways of calculating food chain length depending on what parameters of the food web dynamic are being considered: connectance, energy, or ...
The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along the chain can form either a one-way ...
[3] [4] Beyond its use to distinguish different types of food from each other, nutrient density allows comparison to be made for different examples or samples of the same kind of food. Nutrient density is correlated with soil quality and mineralization levels of the soil, [citation needed] although the relationship is complex and incorporates ...
He explained the low density of tropical trees and lack of "bunching" of tree types around parent trees for two reasons: (1) the number of seeds decline with distance from the parent tree and (2) that the adult tree, its seeds, and seedlings are a source of food for host-specific parasites and diseases. Using his observations, Janzen created a ...
When also held to normal pressure, ammonia's melting and boiling points are −78 °C (195 K) and −33 °C (240 K) respectively. Because chemical reactions generally proceed more slowly at lower temperatures, ammonia-based life existing in this set of conditions might metabolize more slowly and evolve more slowly than life on Earth. [55]
The zinc content of commercially available plant-based food ranges from 3 to 10 μg/g fresh weight. [77] Copper: Essential micronutrient: Cu 2+ 0.01 [71] 1 [70] CuSO 4: Plant sensitivity to copper is highly variable. 0.1 ppm can be toxic to some plants [71] while a concentration up to 0.5 ppm for many plants is often considered ideal. [70 ...