Friday, September 14, 2012

Science Week 6: Parasites and Nitrogen

This wraps up the first 6 week section for our science year already. This unit on Algae and Fungi was fun, and I'm sure as autumn creeps in and our woods become a bit more inviting (read: a few less snakes, ticks, and bugs etc...), we'll go back through those mosses and lichens. With near 20 acres out here of mountain nothingness, we have a wide assortment of them for study.

Onward to the parasites and nitrogen traps...commonly known types like ringworm and athlete's foot, mildews, rusts, and blights, even a less commonly known variety of parasite known as smuts. So, this week's notes:

  • fungi are thallophytes which are....plants without true roots, stems or leaves.
  • a fungus that lives on dead plant or animal material is a...saprophyte.
  • most gilled mushrooms are saprophytes. Nearly every gilled mushroom is found growing on the ground, rotted logs, rotting stumps, even dead limbs on living trees. Less than 1-in-20 mushroom species grows on living wood.
  • Saprophytes are soil builders. They change dead plant/animal material into carbon dioxide and simple elements. This is only one class of fungus...the other class is called parasite because they live off live plant and animal material.
"Bracket" or "shelf" fungi can be found in wooded areas growing on the sides of trees, fashioning themselves as little shelves, perhaps for elves! Fungi do not photosynthesize, as do other plants. They get their nourishment from a host they live on. If a plant gets its nourishment from a host organism that is dead and decaying, it is called a saprophyte. If the host is a living organism, the feeding plant is called a parasite.Are bracket fungi saprophytes, parasites, or both?Trees have tiny tubes that transport water, nutrients, and waste throughout their system. These tubes are called xylem (which transport wastes) and phloem (which transport food). Trees grow from the outer layer just beneath the bark. The bark is not living. Our project is to locate bracket fungi and carefully chip away at the bark of the host tree and see if any "roots" or threadlike structures penetrate through the bark and into the live layer of the tree. If this is the case, then bracket fungi is most likely a parasite. If not, it is most likely a saprophyte.Procedure 
In a forest or wooded area, locate trees on which bracket fungi are growing. Using a chisel, carefully pry pieces of bark off the tree around the bracket fungi. Try to determine if any part of the fungi extends through the bark and into the soft, live layer of the tree. To avoid injuring the tree, do not remove too much bark.
Carefully search through a large area in the forest, noting any presence of bracket fungi. Are the trees where you find the fungi dead or alive, or do you find them on both dead and live trees?       

  •  Fungi are not the only parasites...any plant or animal that grows on another living species or hinders it by taking food, shelter or water is known as a parasite. When one is helped and the other is harmed, it is a parasitic relationship. When each one helps the other it is a symbiotic relationship.
  • Mildew...a whitish grayish fungus seen on the leaves of roses, lilacs, and other plants. Some mildews cause damage, some do not. When the Hebrews were unfaithful to God, He punished them by sending mildew on their crops (Amos 4:9, Haggai 2:17
  • smut is another fungus that grows on plants, commonly ears of sweet corn (appears as clumps of gray swollen cells). The spores spread, blow, and remain in the soil to infect the next season of young crops. Wheat, barley, and corn are all food for smuts.
  • Rust also destroys wheat, oats, barley, and other cereal grains. The red spore stage causes an appearance like rust.  The stem and leaves of a wheat plant become red in the spring, then turn black in the late summer and fall. 
Picture of leaf rust on wheat
  • the black wheat spores can winter-over on the common barberry plant. They form tiny cups on the undersides of the leaves, and in the spring the red spores are developed again and infect the nearby wheat plants.
  • white pine blister rust is white and infects the white pine and wild current bushes.
  • Cedar apple rust lives on the red cedar part of the time, and on apple trees the remainder of the year.

  • All living things must have nitrogen in some form. If nitrogen is absent, life is impossible.
  • algae and fungi live in a symbiotic relationship in lichens, certain bacteria have a symbiotic relationship with lentils, clover, vetch, soybeans, cowpeas, and similar plants. These bacteria grow on the young roots, taking from them food and water. The bacteria draw nitrogen from the air in the soil and mix it with oxygen and other elements to form a solid food used by the plant. Knots of nitrogen called nodules are produced. Later the roots and nodules decay, dissolve in water, and nourish other herbs or trees which in turn benefit man.
  • some soil bacteria do not grow on plant roots but do a similar work. This process is called fixation of nitrogen. This is God's way of providing plants, animals, and man with necessary food elements. 

Nitrogen-fixation process

Stand still, and consider the wondrous works of God....

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