larger tubes on right image form a circular shape.  That belongs to the Eudicot.  

the tubes on the left image are dispersed throughout the entire stucture.  That belongs to a monocot.

define: viral replication: (APRAR)

1. Attachment

    protein on virus chemically locks on to host cell receptors.

2. Penetration

    the genetic material of the virus is injected into the host and enters cytoplasm.

3. Replication

    the viral DNA or RNA is replicated by host.

4. Assembly

    viral components assemble with newly replicated parts.

5. Release

    new viruses are released from host

Give the characteristics that define sponges, cnidarians, flatworms, roundworms, rotifers, mollusks, annelids, arthropods, echinoderms, and chordates

Describe how plants transport water, mineral ions, and organic compounds.

there are two main types of plant tissue that are responsible for transport functions; Xylem for water and mineral ions, and Phloem for organic compounds. 

Xylem is a tissue that consists of tracheid and vessel members.  These cells die at maturity, and connect to form vessels.  The cell walls are then stiffened and water proofed with lignin.  That describes the pathways for water and mineral ions, however, it does not describe the process used to draw water up the length of the plant, going against gravity; for that we need to discuss cohesion-tension theory.  Page 498 says this about cohesion-tension theory: the air’s drying power creates a continuous negative pressure called tension.  This tension extends from leaves to roots.  The drying effect of air causes transpiration as it causes water on the plant to evaporate. The water that is evaporated from the surface of the plant has a pulling effect on the water in the xylem, thus pulling water up the vessels.  It pulls on the entire column of water in the xylem because of the hydrogen bonds that water forms, thus pulling all the water as one unit.

Phloem is a tissue that consists of parenchyma cells, companion cells (albuminous cells), and sieve tubes.  This tissue transports sugar laden fluid to all the parts of the plant that need it.  They can do this because these cells are absent many of the normal organelles one would find in a cells cytoplasm.  The sieve cells have pores are their ends which enlarge over time, to resemble a sieve, which is how it got its name.  This describes the pathways that are used to transport sugar laden fluids (sap) throughout the plant, but not the process itself.  For that, we look to page 503.  Here we learn about translocation and the pressure flow theory.  Translocation occurs when the photosynthetic products flow along a pressure gradient.  Using active transport, the sap moves from the source, into the phloem.  Once in the phloem, a pressure gradient moves material from an area of higher concentrations to an area of lower concentration (sink), such as to the flower or fruit. First, however, water will diffuse from the nearby xylem, and join the sap in the phloem (osmosis!), thus causing a pressure gradient. The pressure flow theory says that pressure builds up at a source, and then pushes the materials to a sink, where the solutes are removed from the phloem. 

This entire process is really cool.  It is neat to know that there is a busy highway of fluids moving throughout the plant, sometimes in opposite directions. 

What internal and external factors govern the growth and development of plants?

Although there are distinct genetic and environmental factors that affect a plants internal and external growth factors, the book points out that the two are inextricably linked. One such external growth factor is the environment, such as the temperature, and amount of water available to the seed.  When there is little water, or when conditions are not favorable for a plant to grow, it becomes dormant.  Dormancy is when an embryo idles in its seed coat for years before it resumes metabolic activity, and continues growing (p524).

Once conditions change to be more favorable, such as more sunlight, or more water, the seed can then begin to germinate.  Germination is the process where a mature embryo resumes growth once water seeps into the seed, and activates enzymes that hydrolyze stored starches into sugar monomers (p524). Germination continues when the seeped water swells the tissue, causing the seed to open, allowing oxygen to enter. The embryo can then use both the sugar and oxygen for aerobic respiration, and cells begin to divide rapidly (p524).

As plants begin to grow, they release hormones in response to environmental stimuli (tropisms).  These hormones (gibberellinis, auxins, abscisic acid, cytokinins, and ethylene) are released, for example, when water is plentiful, or scarce, when the length of night increases or decreases, or when temperature changes.  These hormones control gene expression, solute concentration, and enzyme activity, which affect plant height, shape, and angle of growth (p530).

It is also worth noting that gasses, such as low volumes of O2 and CO2 can also affect plant growth.  In addition, pollution can affect plant growth and development. There is a picture on page 501 that shows the harmful effects of pollution on plant growth.

These processes are genetic (internal), and are linked to environmental (external) triggers

  Describe the lifecycle (gametophyte/sporophyte) of higher plants.  Be sure to include the correct name and the ploidy of each stage and the type of cell division occurring.

I am not completely certain what is meant by “higher” plants.  Google seemed to think that it simply meant vascular plants, so I will move forward with that assumption.  I found a surprisingly large number of illustrations that depict the lifecycle of particular vascular plants; in particular, I will be referencing the material found on pages 377, 381, 384, and 513.

From studying all these illustrations, as well as the one I attached below, it became clear that vascular plants spend part of their life a haploid stage and another part in a diploid stage.  In fact, this question is very similar to one that was asked in assignment 2.  For that question, I answered with the following:

While that answer is technically correct, I doubt it provides the level of detail required to answer this question.

Since vascular plants are sexually reproduced, they cycle between haploid and diploid (alternation of generations).  Haploid refers to a condition in which there is only one set of chromosomes per cell (from one parent), while diploid indicates there are two sets of chromosomes per cell (one from each parent).  We denote the haploid phase as the gametophyte and the diploid phase as the sporophyte.  In vascular plants, the dominant phase is the diploid phase. 

Since vascular plants reproduce sexually, they also undergo fertilization and meiosis.   Fertilization occurs when two haploid gametes (sex cell)s fuse to form a diploid zygote.  Meiosis occurs in sporangia and is a nuclear division in which a diploid nucleus undergoes two divisions, resulting in four haploid nuclei, resulting in four spores.  Those spores then develop into haploid gametophytes, which are multicellular structures that form gametes. 

Growth of the plant occurs via mitosis, which is the formation of new cells by a single division of a nucleus (either haploid or diploid) followed by separation of the cytoplasm.  The end product of a single mitotic division is two new cells that have the same chromosome complement as the parent cell.  Mitosis facilitates growth of a zygote into an embryo as well as further increases in size and growth to form an adult organism.