Which taxa are multicellular

What is the Independent Variable and Dependent Variable?. What brand of soda contains the most caffeine. An independent variable is a variable that does not rely on the other. Other questions:. Which of the following are not included in the Big 6. What would the genotype s. What best explains the observation of an enzyme being selective in the reaction it catalyzes? Each one may be used only once.

Remember me. Not registered? Fast signup. Reference: Buss, L. The evolution of individuality. Heylighen F. Author D. Campbell Date Apr 25, modified Sep created. Next Down. Discussion www. For example, Carl Linnaeus developed a hierarchical system for organizing living organisms Fig.

The highest rank most inclusive was given to kingdom, followed subsequently by phylum, class, order, family, genus, and species. Given the vast scope of his work, Linnaeus completely ignored classifying single-celled organisms.

Antonie van Leeuwenhoek was a pioneer of microscopy and the first person to identify single —celled organisms in His first discoveries were of relatively large microorganisms we now call protists, unicellular organisms with a nucleus. Van Leeuwenhoek never stopped perfecting his microscope, and in he was the first person to identify and describe a bacterium, a very small microorganism lacking a nucleus and true organelles. I n , microorganisms got a major upgrade when Ernst Haeckel proposed that unicellular organisms should be in their own kingdom: Protista.

All multicellular organisms were still classified either as plants or animals Fig. When microscope technology was enhanced during the 19 th century, it became clear that microorganisms were actually two separate groups, based on their internal makeup.

He argued that organisms with the presence of nucleus should all be placed in a large group collectively known as Superkingdom Eukaryota , whether they are unicellular or multicellular. He suggested that all other microorganisms that lack a nucleus were in a separate kingdom: Monera Fig. In , Robert Whittaker recognized an additional kingdom: Fungi Fig.

He argued that fungi were most similar to animals because both groups are heterotrophic they can not produce their own food ; whereas plants are autotrophic they can produce their own food. Further research has supported this hypothesis. Also during the s, Carl Woese and his colleagues began to compare RNA sequences from a wide variety of prokaryotic and eukaryotic organisms. What they found shocked the scientific community Fig. Their work suggested that certain groups of prokaryotes are actually more evolutionarily distant than the groups of eukaryotic organisms, such as plants and animals, are to each other.

Their evidence suggested that all eukaryotic organisms belong in one major monophyletic group Eukarya , while prokaryotes had to be split into two monophyletic groups Bacteria and Archaea.

They inferred that all living organisms should be placed in three domains a newly invented level of hierarchy above Kingdom : Bacteria, Archaea, and Eukarya. However, they were nearly universally accepted by the s. Bacteria and Archaea are prokaryotes, which all lack a true nucleus and membrane-bound organelles; whereas all members of Eukarya have a nucleus encasing linear DNA and many membrane-bound organelles.