<u>Answer</u>:
Option 1.Eukaryotic cells first seen
Option 5. oxygen builds up in the atmosphere
<u>Explanation</u> :
- The name <em>Proterozoic eon</em> is derived from a Greek word which means earlier life.
- This eon represents the time just before complex life started proliferating on earth.
- One of the most important events that took place during this eon was <em>build up of oxygen in the atmosphere</em>.
The fossil evidence also shows the occurrence of <em>advanced single-celled eukaryotes.</em>
<em>So the events that define the Proterozoic eon are eukaryotic cells first seen and oxygen build up in the atmosphere. </em>
Clicking and dragging the labels to the appropriate spot on a sublingual gland's histological slice will rely on Acinus mucous
Mucous acini, which are typically tubular and only contain mucous cells. Serous and mucous cells coexist in mixed (or sero-mucous) acini. In commonly processed tissue sections, the serous cells are "pushed" into a peripheral cap known as a serous Demilune (Demilune is French for half-moon). Mucous acini, which are typically tubular and only contain mucous cells. Serous and mucous cells coexist in mixed (or sero-mucous) acini. Serous cells are "pushed" into a peripheral cap known as a serous Demilune in routinely prepared tissue sections by swollen mucous cells (Demilune is French for "half-moon").
Learn more about Acinus mucous here.
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The adaptations in which the small intestine make for absorption is the presence of a finger-like structure called villi.
<h3>What is Villi?</h3>
These are finger-like structures found in the small intestine which increase the surface area for absorption.
They possess blood vessel which ensures the nutrients are transported to other parts of the body.
Read more about Villi here brainly.com/question/1293500
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90% of the atmosphere is the result of photosynthesis.
