Gram-negative bacteria only have lipopolysaccharides and outer membranes. Both gram-positive and negative bacteria have peptidoglycan, plasma membranes, and cell walls.

The lytic cycle is a production phage that involves killing host bacteria cells.

Peptidoglycan is a component of the bacterial cell wall. Lipopolysaccharide is a kind of lipid attached to the polysaccharide at the outer membrane of the bacterial cell wall. Protein capsids cover viral nucleic acids. Plasmids are bacterial circular DNA and used for horizontal gene transfer.

Both viruses and bacteria have genetic material of nucleic acid. The protein capsid is one characteristic of viruses but ribosomes, binary fission, and self reproduction are involved in bacteria.

General steps of viral multiplication:

Approaching → penetration → synthesis → assembly → release.

The pathogens of streptococcus are positively affected and the host, the human, is negatively affected. Predation is the relationship between predator and prey.

Trp operon regulates repressible enzyme synthesis for making tryptophan (corepressor) in E. coli bacteria. When tryptophan is bound to an inactive repressor, the inactive repressor becomes an active repressor for operon off. Metabolizing lactose is a reaction in lac operon.

All are correct except C. Viruses are composed of DNA or RNA covered by a protein coat. Prions are only composed of infectious proteins.

Gram-positive bacteria is most vulnerable to reaction by these antibiotics because peptidoglycan of gram-positive bacteria is placed outside the cell membrane.

Mutation and genetic recombination (transduction, transformation, conjugation) are factors of bacterial genetic variation.

All are correct except A. Adenoviruses are DNA viruses.

Arrangement of prefixes: dipole (pair), staphylo (clusters), strepto (chains)

Arrangement of shapes: bacilli (rod shaped), cocci (spherical), spiral (helical)

One of the benefits of microbes is supporting the life of organisms such as obtaining Vitamin K by harboring bacteria in the human large intestine.

Prions, mis-folded proteins, affect brains or neural tissues of mammals and cause Mad Cow Disease (BSE), Creutzfeldt-Jakob disease (CJD), and scrapie disease in sheep.

Viruses are not living organisms and have no cell walls. The cell walls of plants and oomycetes are composed of cellulose. Fungi cell walls are made of chitin and bacterial cell walls are made of membranes and peptidoglycan.

Bacteriophages attach to host cell walls by tail fibers and they put only nucleic acids into the host cells (bacteria) to synthesize at cytoplasm.

Bacteriophage T4, which is composed of polyhedral head, tail sheath, and tail fiber, infects only E.coli bacteria. This virus contains DNA and has only lytic cycle called virulent phage. Bacteriophage lambda has both lytic and lysogenic cycles.

Analogous structure means similar function but different structures between two different organisms. Bacterial cell walls are made of peptidoglycan and plant cell walls are composed of cellulose.

All are found in bacterial cells except B. Lysosomes are found in most eukaryotic animal cells.

E.coli bacteria have positive chemotaxis, thereby they move toward the stimulus. Kinesis is a simple change of rate of stimulus response. Migration is genetically programmed movement in a population. Flagellum is a structure for movement of prokaryotic organisms.

Since bacteria are asexual organisms they do not use the meiosis process and sexual reproduction. I and IV are false statements.

Viroids are usually plant pathogens.

Adenoviruses, Tobacco mosaic viruses, and Papillomaviruses are naked viruses. Bacteriophages do not have envelopes also.

When the allolactose binds to an active repressor, the active repressor becomes an inactive repressor. Therefore, increased transcription of lac operon’s gene produces three enzymes (β-Galactosidase, permease, and transacetylase) continuously. However, when the allolactose is mutated, active repressor is bounded at operator and then RNA polymerase stops working.

Capsids enclose viral nucleic acid and transfers its viral nucleic acid into the host cells.

Retroviruses have the most complicated reproductive cycle. They synthesize new genomes by reverse transcriptase, which synthesize DNA from viral RNA. DNA virus synthesizes new genomes from viral DNA. RNA virus synthesizes new genomes from viral RNA such as Tobacco mosaic virus. Phage T4 contains DNA and synthesizes new genomes from incorporation phage DNA with bacterial DNA.

Facultative anaerobes, such as E. coli bacteria, synthesize ATP in an aerobic environment and do fermentation in an anaerobic environment. A is correct for obligate aerobes and B is true for obligate anaerobes.

Bacteriophages are viruses and have only a lytic phage. They contain DNA and synthesize their genomes at cytoplasm in the host cell. Bacteriophages are not animal viruses.

Penetration is the process by which viruses enter into a host cell. Conjugation is directly transferring genetic material from one bacterium to another. Transformation is genotypic or phenotypic change by combining foreign DNA. Binary fission is prokaryotic asexual cell division.

I, II, and III are correct statements. Bacteria directly transfer genetic materials to others by conjugation.

HIV (Human Immunodeficiency Virus), which causes AIDS, is a retrovirus.