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3.1 What Is a Cell?
1. What does the cell theory state? The cell theory states that a cell is the basic unit of life, all organisms are made up of cells, and cells come only from preexisting cells.

2. Why are cells so tiny? The size of a cell is explained by considering what the most favorable surface-area-to-volume ratio of the cell is. Volume represents need the need of a cell, as a cell gets larger in volume its surface area actually decreases thus explaining why it is more favorable for a cell to be small.

3. How do the light microscope and electron microscopes differ from one another? Light microscopes use light rays passing through glass lenses to magnify objects, allowing the human eye to view the image directly. Unlike the electron microscope light microscopes have the ability to view living specimens also. Transmission electron microscopes use a stream of electrons to produce magnified images onto fluorescent screens or photographic film (because the human eye cannot see the image directly). Electron microscopes also have higher resolving power producing magnifications much higher than light microscopes. Also cells can be colored after the micrograph is obtained in electron microscopes, whereas in light microscopes cell must be stained with dyes before viewing them. Another difference between the two is that some electron microscopes can produce three-dimensional views of the surface of the object.

6.3 White Blood Cells and Defense Against Disease
1. What are the different types of white blood cells? White blood cells are classified into the granular leukocytes and agranular leukoctes because some have noticeable granules and some do not. The different types of white blood cells are: neutrophils, eosinophils, basophils, lymphocytes, and monocytes.

2. What is the structure and function of each type of white blood cell?
 * Granular Leukocytes**
 * __Neutrophils__ account for 50-70% of all white blood cells, usually first responders to bacterial infections. Their intense phagocytic activity is essential to overcoming an invasion by pathogen. Pus is a result of their death in large numbers. They have multilobed nucleus and the granules do not significantly take up the stain eosin.
 * __Eosinophils__ increase in number in the event of a parastic worm infection or an allergic reaction. They have a bilobed nucleus and large abundant granules which take up eosin and become red.
 * __Basolphils__ release histamine associated with allergic reactions. They have U-shaped or lobed nucleus and their granules take up the basic stain becoming a dark blue color.
 * Agranular Leukocytes** do not have granules and have nonlobular nuclei.
 * __Lymphocytes__ account for 25-35% of all white blood cells and are responsible for specific immunity to particular pathogen and their toxins (poisons). There are two types: B cells, which produce antibodies, the proteins that combine with target pathogens and mark them for destruction; T cells, which directly destroy pathogens.
 * __Monocytes__ stimulate other white blood cells to defend the body, they are the largest of the white blood cells and are located in tissues.

3. Name and describe three disorders of white blood cells.
 * 1) SCID – Severe combined immunodeficiency disease occurs when the stem cells of white blood cells lack the enzyme, adenosine deaminase. Without this the body cannot fight infections of any sort.
 * 2) Leukemia refers to a group of cancerous conditions that involve uncontrolled white blood cell proliferation. These white blood cells are abnormal or immature thus incapable of performing their normal defense functions.
 * 3) Infectious mononucleosis caused by Epstein-Barr virus, an infection of lymphocytes.

18.1 Chromosomes and the Cell Cycle
1. What are the three stages of interphase?
 * 1) G1 stage occurring before DNA synthesis
 * 2) S stage includes DNA sythesis
 * 3) G2 stage occurring afer DNA synthesis

2. How does interphase prepare a cell for cell division? The cell grows larger, the number of organelles doubles, and the amount of chromatin doubles as DNA synthesis occurs.