BIOL 2604 EXAM 1 QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026

BIOL 2604 EXAM 1 QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026 The Earth was sterile until about _________ - Answers 4 bya The first ________ years of life on Earth were microbial - Answers 3 billion ______ produced O2 about 2.5 bya which helped facilitate other life - Answers Cyanobacteria Robert Hooke - Answers - Late 1600s - First to observe and describe microorganisms - Saw fungi/yeast only, no bacteria - 30x microscope - Wrote Micrographia: a book about what he saw Antoni Van Leeuwenhoek - Answers - Late 1600s - Lens grinding as a hobby - 300x microscope - Was able to see bacteria Edward Jenner - Answers - Late 1700s - Created immunization for small pox - Cow pox and small pox viruses were very similar - Those who were infected by cow pox did not get infected by small pox Louis Pasteur - Answers - Mid 1800s - Disproved Spontaneous Generation - Used swan-necked flasks to prove growth was solid rather than gaseous - Vaccines for anthrax, fowl cholera, and rabies Joseph Lister - Answers - Mid 1800s - Sterilization and disinfection of surgical rooms and instruments Robert Koch - Answers - Late 1800s - "Does a specific species cause a specific disease?" - Used potato slices, gelatin, and starch as early Petri dishes - 4 postulates Koch's 4 Postulates - Answers 1. Organism must be found in infected animals, but not in healthy animals 2. Organism should be grown in a pure culture away from the animal body 3. Cells from pure culture should cause symptoms in another infected animal when inoculated 4. Organisms should be re-isolated, re-cultured, and should be the same as the beginning Martinus Beijernick and Sergi Winogradsky - Answers - 1800s into the 1900s - Isolated microorganisms from environmental soil and water samples - Winogradsky Column - Showed chemolithotrophy - Fixation of CO2 is not always linked with photosynthesis - Showed fixation of atmospheric nitrogen (N2 gas) into cell nitrogen -- organic amino compounds Spontaneous Generation - Answers - The theory that organisms "magically" appeared from natural elements - For example: maggots on rotting food Spontaneous Generation competing theories - Answers - Air and "vital force:" gas particles - Air and seeds/germs: solid particles Pure Culture - Answers - Koch and Petri - Agar: not metabolized, less bacteria (Fannie and Walter Hesse) - Spread plate: sample diluted in water, then spread on plate, pure - Streak plate: sample diluted with loop on plate, isolated Magnification - Answers - How much bigger than actual - Objective lens + ocular lens (10x) Resolution - Answers - When you can distinguish between two points - NA: light-gather capabilities by lens - Wavelength + NA Basic Stains - Answers - Cationic (basic): positive dye, binds to (-) parts of cell (cell surface) - Anionic (acidic): negative charge dye, binds to (+) cell components (RNA, DNA, proteins) Differential Stains - Answers - Put samples into two categories - Gram staining: (+) have thick peptidoglycan walls and is purple, (-) have thin walls and is pink Bright Field Microscopy - Answers - Creates contrast by light coming through background - Cells should be stained to be able to effectively block the light - Cannot view live cells Dark Field Microscopy - Answers - Creates contrast by blocking light - Light comes form the side in the objective lens when a specimen scatters light - No staining needed, can view live cells, better resolution than Light Field Phase Contrast - Answers - Special condenser lense - Changes phase of light to the same phase - Light is shifted 1/4 of a wavelength, and objective lens blocks it - Contrast is created, so live cells can be viewed without staining Fluorescence Microscopy - Answers - UV light excites cell molecules - Some autofluoress: photosynthetic - Dyes can be used to tag proteins and structures without interfering with function Electron Microscopy - Answers - Scanning: 3D, cells coated in stain - Transmission: 2D, fixed sample - Both use heavy metal stains, so live cells cannot be viewed - Wavelength = 0.004 nm of e' - Resolution = 0.2 nm Atomic Force Microscopy - Answers - Stylus scans surface of cell - Repulsive forces keep it close, but do not allow stylus to touch surface - Creates contour map All cells have _____, ______, and ____. - Answers - Cytoplasmic membrane - Ribosomes + metabolic enzymes in cytoplasm - DNA Some cells have... - Answers - Cell wall (plant cells, bacteria, fungi): restrict cell volume, resists osmotic pressure - Cytoskeleton (animal cells) Prokaryotic characteristics - Answers - No membrane-bound nucleus - DNA condensed in nucleiod region - Single circular chromosome - Haploid - No sexual reproduction - Some small, circular, extra-chromosomal DNA: plasmids, have unique function, not essential Eukaryotic characteristics - Answers - Internal membrane-bound organelles - DNA in membrane-bound nucleus - Multiple linear chromosomes - Diploid, haploid produced by meiosis - Division via mitosis - Sexual reproduction Viruses - Answers - Not cellular organisms - No cytoplasm, ribosome, or metabolic activity - Have nucleic acid genome (RNA/DNA) - Have protein capsid - Sometimes have lipid bilayer membrane around capsid - Must infect prokaryotic or eukaryotic cell to reproduce Linnaeus - Answers - 1750s - 2 kingdoms: animalia and plantae - No prokaryotes Haekel - Answers - 1850s - 3 kingdoms: animalia, plantae, protista (all microorganisms) - Liked Darwin's theories, so used tree to depict - Created "phylogeny" - evolutionary history/relatedness of organisms Whittaker - Answers - 1970ish - 5 kingdoms: animalia, plantae, protista, fungi, and monera (bacteria - common ancestor) Molecular approach to phylogeny - Answers - Carl Woese (1970) - DNA -- RNA -- Protein - Transcription (RNA pol), translation (ribosome)