Friday, September 7, 2012

Science Week 5: Soil Makers, molds and yeasts

Remember the story of Joshua and the elders of Israel meeting with the ragged, dusty men on a long journey? These men tricked Joshua, saying they had traveled so far...look at our ragged clothing, our worn out shoes, our moldy bread...though in truth, they had begun their mere 20 mile, 3 day journey with ragged clothing, battered shoes, and moldy bread.


  • Fungi do not have chlorophyll and cannot carry on photosynthesis. Fungi obtain their food in two ways and are classified according to this characteristic. 
  • One fungi group known as saprophytes, feeds on dead plants and animals. (There's a nice entry on fungus in general here at Encyclopedia Brittanica online).  Without saprophytes, every tree, plant and animal that has ever died would still be here, except those parts eaten by scavengers. They years would pass and the dead materials would simply pile up. Forests would be clogged, soil buried, and no new life would develop. 
Characteristics of Saprophytes:
  • Saprophytes have no leaves, stems and roots.
  • They have no leaves mean they have no chlorophyll that plays a vital role in the process of photosynthesis and so they do not manufacture their own food.
  • They are heterotrophic.
  • They derive their energy from a saprophytic or a parasitic existence.
  • They are mostly unicellular
  • They are amoeboid
  • They are filamentous.
  • They reproduce by sexual or asexual spore formation or simply by division.
Therefore, Saprophytes have to necessarily depend on rotten plants for their food.
  • Without saprophytes, no new soil would develop. God designed saprophytes to change the animal and plant matter into carbon dioxide and simple materials that help build new soil. This process provided by the saprophytes completes the food chain (food chain notes at Enchanted Learning...some notes and an online game at Sheppard Software...an online food chain game at EcoKids).   
  • Green leaved plants are usually the beginning of the food chain, and fungi are the final link in the chain.
  • Bacteria, molds, and yeasts are all fungi. Bacteria are the smallest fungi and cannot be seen by the naked eye. Some fungi multiply by tiny spores that are present everywhere. 
  • mold on oranges is commonly a blue and green powder composed of large numbers of spores, any of these can start a new colony of mold.
  • First discovered by a medical student, Ernest Duchesne, and then re-discovered in 1929 by Alexander Fleming (as an antibiotic) and identified it as a relative of the fungus found on oranges. During World War II, doctors worked with Fleming and from the mold he discovered, developed the antibiotic called penicillin.  
  • Yeasts are common, one-celled fungi living mostly on sugar solutions, making alcohol and carbon dioxide in a process called fermentation.  
  • Yeast from the store are cells held together in a starchy material. They will not multiply when cool and dry, but will ferment when damp and warm.  Bubbles of carbon dioxide that develop when the yeast begins to grow, lift your bread dough and make it light. The carbon dioxide and alcohol are lost in the baking process.
  • Vinegar results from the action of both yeasts and bacteria. Fermentation occurs when the yeasts change the sugar into cider to alcohol and carbon dioxide. Vinegar bacteria and oxygen in the air then turn the alcohol to vinegar.

2 comments:

Eddie said...

I swear, I'm going to stop writing and just start sending people over to your page all the time! Great posts again, thanks for sharing!

Mrs. Dewey Smith said...

Don't do that! I might be on a sort of bloggy roll here right now, but life tends to highjack my roll quite often and I start chasing trails in other directions :oh look...a squirrel:

I have a track record of being hit and miss with the upkeep and feeding of my blogs (why exactly I went and divided things up into 3 of them I still don't understand, LOL) But I totally love that you found things of interest here. Some days my crew thinks I've lost my nut completely and I simply put them to sleep with the school day. It's nice to know someone can use my ramblings :-)