Family Relationships

Monocot Charateristics (corn):

-Has only one seed leaf (cotyledon)
-In monocot plants, the first shoot that emerges from the ground or from the seed is the epicotyl, from which the first shoots and leaves emerge.
-The radicle aborts, and new roots arise adventitiously.
-Some monocots, such as grasses, have hypogeal emergence, where the mesocotyl elongates and pushes  the coleoptile (which encloses and protects the shoot tip) toward the soil surface. Since  elongation occurs above the cotyledon, it is left in place in the soil where it was planted.

Dicot Characteristics (bean):

-Has two seed leaves (cotyledons)
-In dicots, the hypocotyl is what appears to be the base stem under the spent withered cotyledons, and the shoot just above that is the epicotyl.
-Roots grow from the radical and apical meristem.
-Many dicots have epigeal emergence, in which the hypocotyl elongates and becomes arched in the soil. -As the hypocotyl continues to elongate, it pulls the cotyledons upward, above the soil surface

Related Species to Corn:
   -wheat, rice, sugar cane, grass, tulip, lily

Related Species to Beans:
   -sunflower family, rose famil, grapes, strawberries, tomatoes



Reproduction

Steps:

  

- pollen lands on stigma
- pollen tube grows to ovary
- egg is fertilized
- the seed forms after fertilization
- when the seed is ready, the seed is spread
- the seed lands somewhere and germinates



Plant Life Cycle

Sexual reproduction involves the two alternating processes of meiosis and fertilization.

• In meiosis, the chromosome number is reduced from the diploid to the haploid number.
• In fertilization, the nuclei of two gametes fuse, raising the chromosome number from haploid to diploid.

Whatever variation in details there may be from one organism to another, these two activities must occur alternately if sexual reproduction is to continue.

In animals, meiosis generates the haploid gametes — sperm and eggs — directly. These single cells fuse to form the zygote which will develop into another diploid animal.
In most plants meiosis and fertilization divide the life of the organism into two distinct phases or "generations".

• The gametophyte generation begins with a spore produced by meiosis. The spore is haploid, and all the cells derived from it (by mitosis) are also haploid. In due course, this multicellular structure produces gametes — by mitosis — and sexual reproduction then produces the diploid sporophyte generation.
• The sporophyte generation thus starts with a zygote. Its cells contain the diploid number of chromosomes. Eventually, though, certain cells will undergo meiosis, forming spores and starting a new gametophyte generation.

Food Delivery

Translocation: movement of materials from laves to other tissues

   -ex: plants produce carbohydrates inleaves, but other nonphotosynthetic parts need them too, so they are translocated.

Phloem: tissue that carries nutrients. Made of long, continuous strands called vascular bundles that extend throught roots and stems

Nutrient & Water Delivery

Transpiration: process by which plants give off water into the atmosphere in form of water vapor

Turger Pressure:  forces water out through the cell wall. Water is collected in intercellular spaces.

Vascular Tissue: supporting and conductive tissue, consisting of xylem and phloem. It conducts water and minerals upward through the roots

Xylem: contains long cells that transport water

Stomata/Guard Cells: thick inner walls that fill with water during daytime and lose the water at night by opening

How Soil Contributes: chemical composition, nutrients, water, anchoring plants

Casparian Strip: band of cell wall material used to block passive flow of materials into stele of plant

Roots & Soil

Growth

Meristem: tissue consisting of undifferentiated cells
                     -gives rise to various organs
                     -keeps it growing
Primary Growth: occurs at apical meristems and lengthens stems and roots

 Secondary Growth: increases girth of  root or stem & is a result of activity of vascular cambium

Vascular Cambium: lateral meristem that forms secondary tissue & is located between the xylem and phloem

Cork Cambium: secondary meristem that develops in region outside vascular tissues & produces periderm

Auxin:
   -development of embryo
   -leaf formation
   -phototropism
   -root initiation

Cytokinin:
   -promotes cell division in roots and shoots
   -bud growth
   -leaf senescence

Tropism: turning of all or part of an organism in a particular direction in response to an external stimulus

Bean

Young Plant Structure & Function

Germination

To germinate, a seed needs 3 things:
           - water
           - oxygen
           - right temperature

Germination is the sprouting of the seed. The seed swells from intake of water, and the outer coat begins to soften. After the coat breaks, the radicle appears and grows downward due to gravity.

Water - is required for germination. Mature seeds are often extremely dry and need to take in significant amounts of water, relative to the dry weight of the seed, before growth can resume

Oxygen - is required by the germinating seed for metabolism. Oxygen is used in aerobic respiration, the main source of the seedling's energy until it grows leaves.

Temperature - affects cellular metabolic and growth rates. Seeds from different species and even seeds from the same plant germinate over a wide range of temperatures.



Corn Seed

Bean Seed

embryo: baby plant

endosperm: food supply

cotyledon: seed leaf that absorbs food in the endosperm & transports it to the embryo

*bean seed has 2 cotyledons, while corn seed has only 1