commonly referred to as monocots, (Lilianae sensu Chase & Reveal) are flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of the major groups into which the flowering plants have traditionally been divided, the rest of the flowering plants having two cotyledons and therefore classified as dicotyledons, or dicots. However, molecular phylogenetic research has shown that while the monocots form a monophyletic group or clade (comprising all the descendants of a common ancestor), the dicotyledons do not. Monocotyledons have almost always been recognized as a group, but with various taxonomic ranks and under several different names. The APG III system of 2009 recognises a clade called "monocots" but does not assign it to a taxonomic rank. The monocotyledons include about 60,000 species. The largest family in this group (and in the flowering plants as a whole) by number of species are the orchids (family Orchidaceae), with more than 20,000 species. About half as many species belong to the true grasses (Poaceae), which are economically the most important family of monocotyledons. In agriculture the majority of the biomass produced comes from monocotyledons. These include not only major grains (rice, wheat, maize, etc.), but also forage grasses, sugar cane, and the bamboos. Economically important monocotyledon crops include various palms (Arecaceae), bananas and plantains (Musaceae), gingers and their relatives, turmeric and cardamom (Zingiberaceae), asparagus (Asparagaceae), pineapple (Bromeliaceae), water chestnut (Cyperaceae), and leeks, onion and garlic (Amaryllidaceae). Many houseplants are monocotyledon epiphytes. Additionally most of the horticultural bulbs, plants cultivated for their blooms, such as lilies, daffodils, irises, amaryllis, cannas, bluebells and tulips, are monocotyledons
d.during only prophase I and involves exchange between chromatids of homologous chromosomes.
Explanation:
Crossing over is the event that occurs during the pachytene stage of prophase I of meiosis I and results in the formation of new gene combinations, that is, recombination. During pachytene of prophase I, the synapsed homologous chromosomes exchange the genetic segments between them.
To facilitate recombination, synaptonemal complex assists in pairing the homologous chromosomes together during the zygotene stage of prophase I. Zygotene is followed by pachytene. A cut in two non-sister chromatids of a homologous pair, exchange of the broken segments followed by ligation results in recombination. Prophase II does not include crossing over.
When a microbe that is not part of the normal biota enters the body, it is likely to first encounter first line of host defense.
The term "normal microbiota" describes the microorganisms that are present in every human's conjunctiva, oral mucosa, skin's surface and deeper layers, saliva, and gastrointestinal tracts. The host employs a number of defences to defend against infection.
Mucus, which has a variety of normal microbiota that compete with and may even destroy invasive bacteria and virae, is one of the body's first lines of defence.Once a virus or bacteria penetrates the skin and mucosa, the host may experience changes that lessen the invader's power. A fever is one instance of such a shift.
Therefore, When a microbe that is not part of the normal biota enters the body, it is likely to first encounter first line of host defense.
Methanesulfinic acid (MSIA) is an important intermediate in the oxidation of dimethyl sulfide (DMS) in the marine boundary layer. The oxidation of MSIA by ozone in the gas phase to form methanesulfonic acid (MSA) was investigated using theoretical calculations in this paper. Three pathways can be found for the reaction of MSIA with ozone. The highest energy barrier is 13.02 kcal mol−1 in the most favorable pathway. By comparing the reaction rate of MSIA + O3 with that of MSIA + OH, it can be concluded that the oxidation of MSIA by O3 to form MSA is of minor significance relative to its oxidation by OH radical in the gas phase. This study can provide some information for the theoretical and experimental studies in the significantly heterogeneous and aqueous-phase oxidation of MSIA by O3.
