<u>Answer:</u>
Scientist think colonies of Cyanobacteria called stromatolites were responsible for the introduction of oxygen into earths atmosphere is true.
<u>Explanation:</u>
- In primeval earth’s atmosphere, stromatolites (colonies of Cyanobacteria) are believed to have increased the level of oxygen by their photosynthesis process.
- These are the first known organisms that started photosynthesis process and produced the oxygen to the earth’s atmosphere.
- There is a theory that, these organisms produced oxygen in the environment and the organism disappeared that couldn’t live in the atmosphere with the oxygen.
- Scientists gave this a name called as “great oxygenation event”.
In the field of histopathology, the tissues to be observed under the microscope are cut in very thin slices. The thin slices make the tissue transparent, and thus, it becomes easier to observe the internal structures and accurately diagnose a disease. The tissues slices cut for the observation are generally not more than 3 micro meters in their thickness.
Hence, the answer is 'to make the tissues transparent and easier to observe'.
www.chegg.com/homework-help/questions-and-answers You recently discovered four new chemical mutagens (#1 - #4), but you do not know what type(s) of mutations these chemicals induce. You exposed E. coli to each chemical individually and observed mutant phenotypes. You then exposed this bacteria to a second known mutagen to observe if the mutations from chemicals #1 - #4 could be reversed. Your data is presented below. Mutations Induced by Mutations Reversed by Chemical EMS Acridine Orange 5-Bromouracil #1 No Yes No #2 Yes No Yes #3 Yes Yes Yes #4 No No No What type(s) of mutations are likely produced by chemical #3? A. transversions B. transitions C. frameshifts What type(s) of mutations are likely produced by chemical #4? A. transversions B. transitions C. frameshifts (SELECT ALL THAT APPLY)
