biology 20 & 23

1. Briefly describe the structure of a virus.

Outer capsid composed of protein subunits and a nucleic acid core composed of either DNA or RNA

2. Briefly describe the lytic cycle and the lysogenic cycle of bacteriophages.

Lytic Cycle: Release of new viruses lyses (ruptures) host cell

Lysogenic Cycle: Viral DNA inserts into host cell chromosome and does not actively replicate; viral DNA called prophage; prophage replicated along with bacterial chromosome; some later trigger can induce prophage to re-enter lytic cycle.

3. Briefly describe the life cycle of a retrovirus.

 Nucleic acid is RNA; viral RNA gets into cell and is used to make DNA; DNA inserts into host chromosome; new viral RNA and capsid made by host cell; maturation and release follow; release by budding eventually kills cell.

4. Briefly describe 3 ways genes are transferred in bacteria.

 Conjugation: two bacteria are temporarily linked together, often by means of conjugation pious. While they are linked, the donor cell passes DNA to a recipient cell in the form of a plasmid

Transformation: Occurs when a cell picks up free pieces of DNA secreted by live prokaryotes or released by dead prokaryotes

Transduction: Bacteriophages carry portions of DNA from one bacterial cell to another. Viruses have also been found to infect archaeal cells, so transduction may [lay an important role in gene transfer 

5. What is the difference between an autotroph and a heterotroph?

 Autotrophs make their own food, while heterotrophs rely on other organisms for food.

6. Briefly describe the three main shapes of bacteria.

Spirilli: spiral-shaped or helical-shaped

Bacilli: rod-shaped

Cocci: round or spherical

Briefly describe alternations of generations in plants.

 Two multicellular individuals alternate; each producing the other; diploid sporophyte produces haploid spores; spore germinates into haploid gametophyte; gametophyte produces gametes, which fuse to form diploid zygote; zygote grows into sporophyte.

2. List and describe the parts of a complete flower.

 Sepals: protect bud before it opens; collectively called calyx

Petals: colored leaflets; collectively called corolla

Stamens: male parts; filaments and anther; pollen produced in anther

Carpel: female parts; stigma, stalk, ovary

Complete flower has all four parts; incomplete flower lacks one or more parts

3. Match each of the following plants with the correct category

     A. Bryophytes                         d_____Flowering plants

     B. Seedless vascular plants   c_____Cone bearing plants

     C. Gymnosperms                   a_____Mosses

     D. Angiosperms                     b_____Ferns

4. List the characteristics of all plants.

 Multicellular, eukaryotes, usually specialized tissues, photosynthesizers that became adapted to living on land; alternation-of-generations life cycle; sessile

5. Define fruit.

A covering for a seed derived from an ovary

6. Briefly describe an archegonium and an antheridium.

Archegonium: female gametangia; produce eggs

Antheridium: Male gametangia; produces sperm

1. Describe the different types of symmetry.

 Asymmetry: no particular pattern to body shape

Radial symmetry: Body organized circularly; similar to a wheel

Bilateral symmetry: Definite right and left halves; humans have bilateral symmetry

2. What are the differences between protostomes and deuterostomes?

 Protostomes: Blastopore becomes mouth; ventral nerve cord ; spinal cleavage

Deuterostomes: Blastopore becomes anus; dorsal nerve cord; radial cleavage

3. What animals are in each of the following phyla?  What characteristics are unique to each phyla?

  A. porifera: sponges; no symmetry; no tissue; filter food particles from water

  B. cnidaria: Jellyfish, corals, sea anemones; radial symmetry; tissues; stinging tentacles; olyp has mouth directed upward; Medusa has mouth directed downward

  C. mollusca: Snails, clams, oysters, squid, octopus; all have a mantle, a visceral mass, and a foot

  D. annelida: segmented worms; earthworms, leeches; body segments repeated along length of body

  E. platyhelminthes: Flatworms; planaria, tapeworms; flat body; no body cavity

  F. nematoda: Roundworms; non-segmented body; some are parasites

  G. arthropoda: Exoskeleton; jointed appendages; segmented body; crustaceans; crabs, shrimp, lobsters, crayfish

  H. Echinodermata: Starfish; deuterostomes, water vascular system; radial symmetry in adult; bilateral symmetry in larva

1. Define endothermic and ectothermic.  Which vertebrates are endothermic?  Which vertebrates are ectothermic?

 Ectothermic: Body temperature stays relatively the same as the environment; Amphibians, reptiles, fish

Endothermic: Internal way to control body temperature; Birds, mammals

2. Define monotreme and marsupial.

 Monotreme: Mammals that lay eggs; includes duck-billed platypus and spiny anteater

Marsupial: Mammals with pouches; young born very immature; complete development in mothers pouch, where mammary glands are located; includes kangaroos, koalas, and opossums 

3. List the characteristics of all chordates.

Deuterostomes; postnatal tail; notochord; dorsal tubular nerve cord; pharyngeal pouches