Mr. T's Science Scene

Seeds

Seeds are the things produced after a flower has been pollinated.  The seed contains nutrients and an embryo.  A seed is the "eggs" of the plant world!

So, the seed itself is called a cotyledon (but all of us run around talking about seeds).  Some seeds have a single cotyledon and are called monocots (grasses such as lawns, corn, wheat, etc., and palm trees are monocots).  Some seeds have a seam down the middle and two halfs or two cotyledons to their seeds.  They are called dicots. (maple trees, beans, sunflower seeds, peanuts, walnuts, pumpkin seeds, etc. are all dicots).  Another way to tell dicots and monocots apart is the veining in the leaves; dicots have spread out veins and monocts have veins in a straight line and parallel to the leaves.

The seed is surrounded by a thin coating (the seed coat) which protects it from drying out and from bacteria and fungus.  That sounds a little strange because most seeds look and feel dried out- and they are.  BUT, when you plant them and water them, the seed absorbs water and the seed coat helps to keep that water inside.

Speaking of inside, if you break open a dicot seed (or monocot) you will see the plant embryo . . . READ MORE


Plant Structures

Plants, like all organisms, have cells, tissues, organs, and organ systems which make them up.  When we talk about plants, however, sometimes it is easier to refer to their organs and organ systems as structures and systems.  The plant has similar systems to an animal  but is much less complex.  The following systems are those that are most important:


1.  Flowers (more on these at a later date):  The reproductive system involves the plant's flowers.  Flowers are expensive (sugar-wise) so they make them and get rid of them.  Few plants will sustain a flower their entire growing season!  Angiosperms are plants with a "typical" flower.  Gymnosperms are evergreens (shrubs, pine trees, etc.).  They both have flowers but you wouldn't give a boquet of gymnosperm flowers to your mom!


2.  Leaves:  Because a plant can't "get up and go get food" a plant has to have a way to make its food (autotroph).  It accomplishes this through the process of photosynthesis which happens in the leaves.  Chloroplasts use light, CO2, and water to make sugar . . . . READ MORE


Photosynthesis (and Respiration)

PLANTS CAN'T MOVE!!


Plants can't move- which is why they have evolved to be able to do certain things that animals cannot.  Photosynthesis is one of those things.  In a nutshell, photosynthesis is a process whereby light (photo) is used to make sugar (synthesis).  In reality it is a little more complicated than that and involves the manipulation of atoms found in carbon dioxide, water, glucose, and oxygen.

Before we get into the chemical process of photosynthesis and respiration you may need a littel chemistry refresher:

Molecules are made of atoms!

In NaCl there are two atoms in the molecule of salt (1 sodium (Na) and 1 chlorine (Cl).

In N3CH4 there are a total of 8 atoms (3 Nitrogen, 1 Carbon, 4 Hydrogen)

In 2 H3O2 there are two molecules each with 5 atoms (3 Hydrogen and 2 Oxygen).  The total atoms of both molecules is 10.

If a number is in front of the molecule there are that many molecules.  If a number is to the right of an element's letter symbol, there are that many atoms.

If there is a number in front AND a number after the elemental symbol, you multiply both numbers for a total number of atomes.  2 H2O = 4 hydrogen and 2 oxygen.. . . . READ MORE