Biodiversity generally refers to the variety and variability of life on Earth. According to the United Nations Environment Programme(UNEP), biodiversity typically measures variation at the genetic, species, and ecosystem level.[1] Terrestrial biodiversity tends to be greater near the equator,[2] which seems to be the result of the warm climateand high primary productivity.[3] Biodiversity is not distributed evenly on Earth, and is richest in the tropics. These tropical forest ecosystems cover less than 10 percent of earth's surface, and contain about 90 percent of the world's species.[4] Marine biodiversitytends to be highest along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity.[5]Biodiversity generally tends to cluster in hotspots,[6] and has been increasing through time,[7][8] but will be likely to slow in the future.[9]
Rapid environmental changes typically cause mass extinctions.[10][11][12] More than 99.9 percent of all species that ever lived on Earth, amounting to over five billion species,[13] are estimated to be extinct.lstimates on the number of Earth's current species range from 10 million to 14 million,[f which about 1.2 million have been documented and over 86 percent have not yet been described] More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described.[18]The total amount of related DNA base pairson Earth is estimated at 5.0 x 1037 and weighs 50 billion tonnes.[19] In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC (trillion tons of carbon).[20] In July 2016, scientists reported identifying a set of 355 genes from the Last Universal Common Ancestor (LUCA) of all organisms living on Earth.[21]
The age of the Earth is about 4.54 billion years.[22][23][24] The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago,[25][26][27] during the Eoarchean Era after a geological crust started to solidify following the earlier molten HadeanEon. There are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia.[28][29][30] Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old meta-sedimentary rocks discovered in Western Greenland.More recently, in 2015, "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia.[32][33] According to one of the researchers, "If life arose relatively quickly on Earth .. then it could be common in the universe.
decreased and then increased after major waves of mass extinctions
Answer is.
Conduction and convection are means of transferring heat, the important difference is the medium through which the heat travels. Conduction occurs when heat is transferred through solid objects, like a bar.
Answer:
D&A
Because the Digestive system breaks down food( which starts in the mouth because of the eynzemes) Then is broken down in the stomach (mechanical digestion) then the water and nutrients are absorbed in the small intestine, in the large intestine the rest of the nutrients are absorbed. Also, I just did the last test and finished this section in science
Answer: sexual reproduction.
Explanation: In asexual reproduction there is no exchange of genetic characteristics due to the lack of fusion of gametes(haploid). Thus there is practically no variation in specie.
But in sexual reproduction there is exchange of genetic characteristics resulting from the fusion of haploid gametes hence there is variation and great diversity.
