Wednesday, November 9, 2022

Week #13 recap (so far)

 November 9th - Wednesday - Week #13 - 

     Hi Scientists;

     I made a very exciting 14 minute video, yesterday, as a recap. When it was done, it would have been posted but - for some technical reason beyond the scope of an old science teacher - there was no sound.

     Which was, probably, just as well. Fourteen minutes is too long for a recap. Heck, my own teenagers wouldn’t listen to me for more than five minutes. So … the notes are posted and here’s a bullet-point recap for the last three days. The important things we’ve been trying to teach and the tidbits that are snuck in so students remember this for high school, and beyond.

  • Earth was formed, about, 4.5 billion years ago and life arose about 3.6 billion years ago. The vast history of life on Earth has been one-celled organisms. 
  • The oxygen content of our atmosphere didn’t build up to a level high enough to sustain respiration until photosynthesizing bacteria had been around for, about, two billion years. In other words; if you had a time machine with a “random” button and you wanted to go back in time to see ancient life; most of the time you’d step out of your machine to see nothing more than green, slimy rocks. (Stromatolites.)
  • When life finally did inhabit land it diversified into the six Kingdoms we now recognize. (Although, the Protist kingdom will be subdivided soon.) Bacteria has no specialized organelles, while animals, plants, and fungi do have nuclei and specialized organelles.
  • Our job, this week, has been to identify the structure and function of organelles. Text books love to compare cells to factories. (I suppose that comes from the industrial revolution and the view that everyone knows how factories work?) We use that analogy as it is in our text and in various handouts. The product of these factories is proteins; built up from smaller parts called Amino Acids.
  • There are three, important, chemical reactions we should know going forward - photosynthesis, respiration, and fermentation. We introduced fermentation this week by making wine (yes, wine) and using that as a vehicle to discuss the things that come together to make the geology, ecosystem, and geography of California possible and how water, plants, fermentation, and the physical laws we studied in weeks one through eleven - combine to make the California we know today.
  • The quiz, this week, will focus on the organelles and kingdoms of life.

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