Sand is a granular material composed of finely divided rockand mineral particles. It is defined by size, being finer than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.[1]
The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastalsettings is silica (silicon dioxide, or SiO2), usually in the form of quartz. The second most common type of sand is calcium carbonate, for example, aragonite, which has mostly been created, over the past half billion years, by various forms of life, like coral and shellfish. For example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean.
Sand is a non-renewable resource over human timescales, and sand suitable for making concrete is in high demand.[2] Desert sand, although plentiful, is not suitable for concrete, and 50 billion tons of beach sand and fossil sand is needed each year for construction.
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Chordates share some common traits. At some point in their life cycle, they have a notochord, a nerve cord, and pharyngeal (fayr uhn JEE uhl) slits in the neck or throat. The notochord is a flexible rod that supports the animal's back. ... Sharks are one type of vertebrate animal that have backbones made of cartilage.
Carbon Monoxide. Carbon Monoxide is polluting the air not water, everything else on the list is something that can pollute the water.
Capillaries<span> are </span>small<span>, thin </span>blood vessels<span> that connect the </span>arteries<span> and the veins. Their thin walls allow oxygen, nutrients, carbon dioxide and waste products to pass to and from the tissue cells.</span>
The duplication of homeotic ( H o x ) genes has been significant in the evolution of animals because it <u>permitted </u><u>the </u><u>evolution </u><u>of novel forms</u>
<h3>What is the Hox genes and evolution?</h3>
Hox proteins are a family of transcription factors that have undergone extensive conservation. They were first identified in Drosophila for their crucial functions in regulating segmental identity along the antero-posterior (AP) axis.
The regionalization of the AP axis and changes in the expression patterns of these genes have been strongly correlated during the past 30 years across a wide range of evolutionarily distinct species, indicating that Hox genes have been essential in the evolution of new body plans within Bilateria.
Despite this extensive functional conservation and the significance of these genes for AP patterning, many important concerns about Hox biology remain.
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