Because of their resemblance and relationship to prehistoric reptiles and many people think that birds descended from dinosaurs
The teacher
should discuss safety procedure with students at the beginning of the experiment
or laboratory assignment. The teacher
should give list of rules for students.
1.
Always wear safety goggles.
2.
Never
touch or rub eyes of face during science investigation.
3.
Keep lids on when not in use.
4.
Never use broken/chipped glassware.
The first known single-celled organisms appeared on Earth about 3.5 billion years ago, roughly a billion years after Earth formed. More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.
I believe its when you <span>silencing one of the two X chromosomes in female cells...
Hope I helped
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