EO4

(The Diversity of Life) = For TSW 1-4 see the power points I did listed under files on the menu. =
 * __LIFE SCIENCE 12/13 __**  **__ESSENTIAL UNIT 4 (E04) __**

5. TSW name the characteristics of viruses and explain how they interact with the living world. **General Characteristics of Viruses** Viruses are infectious agents with both living and nonliving characteristics. They can infect animals, plants, and even other microorganisms. **1. Living characteristics of viruses** >> a. They **reproduce** at a fantastic rate, but only in living host cells. >> b. They can **mutate.** **2. Nonliving characteristics of viruses** >> a. They are **acellular**, that is, they contain no cytoplasm or cellular organelles. >> b. They **carry out no metabolism on their own and must replicate using the host cell's metabolic machinery**. In other words, viruses don't grow and divide. Instead, new viral components are synthesized and assembled within the infected host cell. >> c. TThe **vast majority of viruses possess either DNA or RNA but not both**. **3. Criteria used to define a virus** >> a. The vast majority of viruses contain only one type of nucleic acid: DNA or RNA, but not both. >> b. They are totally dependent on a host cell for replication. (They are strict intracellular parasites.) >> c. Viral components must assemble into complete viruses (virions) to go from one host cell to another. **4. Laboratory cultivation of viruses** 6. TSW describe the reproductive cycle of a virus. <span style="font-family: Arial,Helvetica,sans-serif;">Since viruses are totally dependent on their host cell for reproduction, they cannot be grown in synthetic culture media.



7. TSW name the characteristics of bacteria, explain how they get food and energy and how they reproduce.

<span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">**General Characteristics of Bacteria**

<span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">The following characteristics are common to most bacteria –
 * <span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">Found everywhere, in all possible habitats.
 * <span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">These are basically unicellular but may live with other cells and form colonies
 * <span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">The bacterial cell is identified by a rigid cell wall
 * <span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">Bacteria is devoid of any nucleus, nucleolus or nuclear membrane.
 * <span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">The DNA is mostly circular in nature and are not associated histone proteins.
 * <span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">None of the membrane bound cell organelle are present like the golgi bodies, endoplasmic reticulum, mitochondria, chloroplast etc. this makes the interior of the cell morphologically simple compared to other eukaryotic (modern) cell types.
 * <span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">The ribosomes are found scattered within the cytoplasm
 * <span style="background-color: #ffffff; color: #333333; font-family: 'Lucida Grande',Arial,Helvetica,sans-serif; font-size: 12px;">A bacterium may possess more than one flagella (locomotive organ-mover)

8. TSW describe the characteristics of each of the three groups of protists and compare and contrast them to animals, plants and fungi. <span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;"> 1. Animal like protists are protists with animal characteristics. They are sometimes referred to as protozoa. They are heterotrophs, and they are __mobile__. <span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;"> An example is a paramecium.

<span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;"> 2. Plant like protists are protists with plant like characteristics. Most carry out photosynthesis. Most of us are familiar with algae, <span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;">which fall in this category.

<span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;"> 3. Fungus like protists are protists with plant like characteristics. Their main characteristic is that they digest food externally. (mold)

9. TSW distinguish between the four groups of protozoans. <span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;">Amoebas and related protozoans do not have cilia and move using extensions of their cell membrane known as pseudopods. The radiolarians construct spine covered shells which are used to catch prey.

<span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;">Cilliates are covered in short hairs called cillia. They use them to swim actively through the water. The paramecium is one of the __best__ known cilliates.

<span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;">Flagellates have one or two especially long cillia known as flagella. Like the cilliates, the flagellates also swim through the water. Some flagellates are (or were) classified as green algae. Diatoms are not protozoa but plant cells. Some flagellates have a very thick cell membrane, these are the dinoflagellates.

<span style="background-color: #ffffff; color: #333333; font-family: arial,helvetica,clean,sans-serif;">Sprorozoans form spores which help them to survive harsh environmental conditions. Many prozoan paracites are sporozoans. One is the malaria organism.

10. TSW identify the characteristics of fungi and recognize their role in nature. (click the link to visit the dictionary). 1. All are eukaryotic and p ossess membrane-bound nuclei (containing chromosomes) and a range of membrane-bound cytoplasmic organelles (e.g. mitochondria, vacuoles, endoplasmic reticulum). 2. Most are filamentousComposed of individual microscopic filaments called hyphae, which exhibit apical growth and which branch to form a network of hyphae called a mycelium. 3. Some are unicellulare.g. yeasts. 4. Protoplasm of a hypha or cell is surrounded by a rigid wallComposed primarily of chitin and glucans, although the walls of some species contain cellulose. 5. Many reproduce both sexually and asexuallyBoth sexual and asexual reproduction often result in the production of spores. 6. Their nuclei are typically haploid and hyphal compartments are often multinucleateAlthough the Oomycota and some yeasts possess diploid nuclei. 7. All are achlorophyllousThey lack chlorophyll pigments and are incapable of photosynthesis.8. All are chemoheterotrophic (chemo-organotrophic)They utilise pre-existing organic sources of carbon in their environment and the energy from chemical reactions to sythesise the organic compounds they require for growth and energy. 9. Possess characteristic range of storage compoundse.g. trehalose, glycogen, sugar alcohols and lipids. 10. May be free-living or may form intimate [|relationships] with other organisms may be free-living, parasitic or mutualistic (symbiotic). 11. TSW apply the process of scientific inquiry in a variety of ways, focusing on observable phenomena and data collection. See Science Fair Project link.