Sunday, April 22, 2012

Monocot

Characteristics:
  • embryo with single cotyledon
  • pollen with single pore
  • flower parts in multiples of threes
  • major leaf veins parallel
  • stem vascular bundles scattered
  • roots are adventitious
  • secondary growth absent

good picture of Bebe corn

Relatives:
  • rice
  • wheat
  • sugar cane
  • banana
  • orchid

Reproduction

This is to show the parts of a flower since bebe corn did not flower.
  • Stamen/ filament/ anther
  • Carpel/ stigma/ style/ ovary
  • Petals/ sepals
  • Pollen/ ovule
  • Double fertilization
   The stamen is the male reproductive organ. The anther is part of the stamen that makes pollen grains, which have male germ cells. The filament is the stalk of the anther, and thus part of the male reproductive organ. The stigma is part of the flower that pollen can stick to. The style raises the stigma away from the ovary in order to avoid contamination by the pollen. The ovary produces ovules, which have the female germ cells. Once the ovules are fertilized by the male germ cells, they develop into seeds in the ovary. The carpel is the female reproductive parts of the flower which includes the stigma, style, ovary, and ovule. Petals aid in pollination and help protect the sex organs. Sepals support the petals and protect the floral parts.

Life Cycle

  1. The sporophyte reproduces through meiosis to make spores.
  2. The spores reproduce by mitosis to make gametophytes.
  3. A male gametophyte fertilizes a female gametophyte.
  4. The zygote becomes a sporophyte through mitosis.
This process is called alternation of generations.

Food Delivery

   Translocation is the re-location of nutrients in the leaves to other tissues/ organs in the plant. Photosynthesis occurs in the leaves and produces carbohydrates (food).  Translocation sends these carbohydrates to parts of the plant that are non-photosynthetic. The carbohydrates are accompanied by other materials such as organic and non organic materials. The food is re-located to such places like roots, stems, flowers, and developing leaves.


Showing the leaves of the bebe corn.




   Phloem is the tissue used for translocation. It carries organic material, mostly sucrose, to all parts of the plant. It mainly transports soluble organic matter that was produced during photosynthesis to parts of the plant that are non-photosynthetic. Phloem is made up of living cells, where as xylem is mainly dead cells.
   Phloem cells:
  • sieve
  • companion / albuminous
Sieve cells have few organelles in them in order to keep the rate of the flow of the nutrients throughout the plant high. These other cells are called companion cells and albuminous cells that control the sieve cells. Theses cells have a nucleus, and much more mitochondria and ribosomes.

Nutrient and water delivery


   Transpiration is like sweating for plants in a way. Transpiration is water vapor leaving the plant through cells called stomata. Typically, this occurs in leaves, but it can also happen in roots, flowers, and stems. Transpiration happens when stomata cells are opened. This process is necessary in order to let in carbon dioxide from the air to use in photosynthesis. Transpiration also cools off the plant, changes the osmotic pressure of the cells, and makes mass flow of nutrients and water from roots to shoots possible.

stomata cells have guard cells over them to control when they are opened or closed. When the cell has swelled with water, the guard cell will open the stomata to let some of it out and to take in CO2.

   Turgor pressure is caused by the osmotic flow of water from an area of low solute concentration outside of the cell to a higher solute concentration in the vacuole. This pressure pushes the plasma membrane against the cell wall of the plant.

   The vascular tissue transports water and nutrients through out the plant, kind of like the circulatory system in animals. There are two main tissues that carry out the functions of the vascular tissue, the xylem and the phloem. There are two meristems within the vascular tissue, the vascular cambium and the cork cambium.

   Xylem is a type of tissue within the vascular tissue of a plant. Xylem transports water and some nutrients from the roots through the rest of the plant. It also replaces water that was lost from photosynthesis and transpiration. Xylem is made up of two cell types called tracheids and vessel elements. These cells are long and the vessel elements are connected together into tubes called vessels.



   Stomata are pores in leaves and stems epidermis that are used for gas exchange. The cells that border the stomata are called guard cells. Guard cells control the size of the opening in the stomata. Oxygen and carbon dioxide enter the plant through stomata and are used in photosynthesis and cellular respiration. At the same time, oxygen is leaving the plant, along with water vapor. Stomata are shaped like an oval. The guard cells are wrapped around the stoma(singular), which makes a circular shape around the stoma.

   Soil affecting plant growth:
  • not enough nutrients, so plant growth is not well
  • high amounts of needed nutrient, plant will thrive
  • clay, sand, and others negatively affect draining of plants, so cause them to not grow well
  • plants anchor themselves in the soil, so if there is not much or it is then they will not last through wind and storms
   Casparian strip: part of cell wall that is chemically different on the endodermis. The endodermis is the innermost layer in some plants that lays between the cortex and the stele. It blocks the passive flow of things such as water and solutes into the stele. The stele is the central part or the root or stem.  

Saturday, April 21, 2012

Growth

Meristem is the tissue in plants that give growth and form organs such as flowers and leaves. The meristem cells can divide continuously and are all the same. They make the basic structure for the plant and help with differentiation in tissues and making new organs.  

There are three types of meristems:
  • apical
  • intercalary
  • lateral

Apical: at tips of stems and roots to increase length at tips and for growth

Intercalary: Between the tip and base of stems and leaves to increase length between nodes

Lateral: at sides of stems and roots to increase diameter


Primary growth happens in all vascular plants. It is the growth of roots and stems in length.

Secondary growth typically doesn't happen in monocots such as corn. Secondary growth is the increase of diameter in roots and stems.

Vascular cambium:
  • make up secondary vascular tissue (sec. xylem and phloem)
  • transport water solutions
  • lateral meristem
  • between tissues of stem and root, sometimes in leaves
Cork cambium:
  • tissue that's part of periderm in vascular plants
  • lateral meristem
  • secondary growth that replaces epidermis in roots and stems
  • produces the cork, protective layer
  • layer of bark
Plant Hormones:
  • Auxin: located in- embryo of seeds, young leaves, meristems of apical buds
                      function- stimulates ceel elongation, vascular differentiation, induces adventitious roots on cuttings, involved in phototropism, gravitropism, stimulates ethylene synthesis, ect.
  • cytokinin: located in- synthesized in roots and transported to other organs
                           function- Stimulates cell division, involved in shoot growth, delay leaf sequence



the leaf of the plant is showing tropism by leaning towards the sunlight 


Young Plant




This is a labeled picture of a young plant to show how my plant compares to the model. Also, to show the primary/ lateral root and the root hairs.


This picture shows several pictures of the coleoptile




This picture shows the dermal tissue of the plant and the cuticle.



This picture shows the adventitious roots of a corn plant because I did not get a picture with the adventitious roots of my plant.




Wednesday, April 18, 2012

Germination


Germination is the process of a plant emerging from a seed, and beginning growth.


there are some requirements for germination:
  • water
  • gases
  • temperature
   Water is needed because it is the essential element for enzyme activation, allows break down of storage reserves, and corn needs 30% moisture to germinate according to the critical moisture content concept.

   In order for a plant to germinate, it needs air/ gasses. Oxygen is the most important because it is used for respiration.

   Different seeds have different temperatures at which they can germinate in.

Imbibition is when water enters the seed through the radical(pointy, lower part of embryo; where root forms.) The water softens the tissue inside of the seed and makes the seed swell up. The seed coat then splits open and lets water in more quickly and allows enzyme activation. The first root can then protrude and growth is activated. At this point, more ATP is produced, thus more respiration and growth. Once an obvious primary root grows germination is done, and the plant is then reffered to as a seedling.


Embryo

   This is a labeled picture of a corn seed; although it is not my baby corn seed.

Embryo: part of the seed that holds parts of the leaves, stem, root, and cotyledon. The plant will start its growth from the embryo, and then develop into the differentiating parts.

Cotyledon: either become the primary leaves or food storage, sometimes both.

Endosperm: the food source within the seed