Study GuidePlant Biology–Systematics1. Plants Among the Diversity of OrganismsLiving organisms on Earth show an amazing variety. To make sense of this diversity, scientists classifyorganisms into groups. However, classification isnot fixed. It keeps changing as new scientific toolsand information become available—especially data fromDNA and RNA sequencing.Because scientists often interpret this data differently,disagreements are common. Some biologistsbelieve organisms that look and behave very differently should not be grouped together just becausetheir DNA is similar. On the other hand,cladistssupport grouping organisms based mainly on sharedancestry shown by molecular data, even if they look very different. This debate is a normal andhealthy part of science.1.1Major Groups and Modern Ways of Classifying OrganismsIn the18th century, classification took a major step forward due to the work ofCarl Linnaeus. Heintroduced a systematic way of naming and grouping organisms.Later, in the19th century,Charles Darwintransformed biology by explaining how organisms evolveover time and share common ancestors.By theend of the 20th century, another revolution occurred. Advances inmolecular sequencingreshaped our understanding of evolutionary relationships. Scientists realized that life on Earth can betraced back tothree major evolutionary lineages, all originating from acommon ancestor.Preview Mode
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