Search results
Results from the WOW.Com Content Network
In a case where scientists studied the behavior of pollen grain germination of eight different species, they concluded that oxytropic behavior is prevalent but unpredictable. Three of the eight species the pollen tube grew away from higher oxygen concentrations, one of the species grew toward the higher oxygen concentration, while the remaining ...
Pollen itself is not the male gamete. [4] It is a gametophyte, something that could be considered an entire organism, which then produces the male gamete.Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell.
The emergence of life with increasing order and complexity does not contradict the second law of thermodynamics, which states that overall entropy never decreases, since a living organism creates order in some places (e.g. its living body) at the expense of an increase of entropy elsewhere (e.g. heat and waste production).
Pteridophyte spores are similar to pollen grains and fungal spores, and are also components of aeroplankton. [ 60 ] [ 61 ] Fungal spores usually rank first among bioaerosol constituents due to their count numbers which can reach to between 1,000 and 10,000 per cubic metre (28 and 283/cu ft), while pollen grains and fern spores can each reach to ...
Earlier pollen researchers include Früh (1885), [16] who enumerated many common tree pollen types, and a considerable number of spores and herb pollen grains. There is a study of pollen samples taken from sediments of Swedish lakes by Trybom (1888); [17] pine and spruce pollen was found in such profusion that he considered them to be ...
Thunderstorm asthma (also referred to in the media as thunder fever or a pollen bomb [1]) is the triggering of an asthma attack by environmental conditions directly caused by a local thunderstorm. Due to the acute nature of the onset and wide exposure of local populations to the same triggering conditions, severe epidemic thunderstorm asthma ...
Pollen grains of entomophilous plants are generally larger than the fine pollens of anemophilous (wind-pollinated) plants, which has to be produced in much larger quantities because such a high proportion is wasted. This is energetically costly, but in contrast, entomophilous plants have to bear the energetic costs of producing nectar.
SEM image of pollen grains. Sporopollenin is a biological polymer found as a major component of the tough outer (exine) walls of plant spores and pollen grains. It is chemically very stable (one of the most inert among biopolymers) [1] and is usually well preserved in soils and sediments.