Question 1

Streptococcus mutans one of the bacteria that can cause the loss of tooth enamel in humans.The metabolic process that this particular species of bacteria uses that can result in enamel breakdown is

Accepted Answer

Streptococcus mutans ferments sugar into lactic acid, which lowers the pH in the mouth and leads to demineralization of tooth enamel. This can result in the development of dental caries or cavities.

Question 2

Which of the following statements about sexually transmitted diseases (STDs)is false?

Accepted Answer

Chlamydia is a bacterial infection and can be treated with antibiotics.

Question 3

The data below shows recombination of genes (1-5)according to the amount of time available for transfer of the bacterial chromosome during conjugation between different genetic strains in E coli? Based on these data,which gene is closest to gene 1? (Note: The entire chromosome is transferred in 100 minutes. )

Accepted Answer

The answer of The data below shows recombination of genes...

Question 4

Which of the following statements about specialized transduction is false?

Accepted Answer

This statement is false. Specialized transduction can sometimes produce partial diploid cells, which carry both the original bacterial genome and the transferred phage DNA. This occurs when the phage integrates into the bacterial chromosome at a site adjacent to a gene, and then the prophage excises imprecisely, leaving part of the bacterial gene behind.

Question 5

You expose a tube of bacteria to ultraviolet radiation to induce mutations.You then spread the bacteria on a plate containing media with all know required nutrients and wait until separate colonies form.Finally,you use replicate plating to transfer a print of this plate to an additional sterile plate containing minimal media plus a known required nutrient for the bacteria.Based on this protocol,colonies growing on the plate lacking a required nutrient would include what type of cells?

Accepted Answer

Colonies growing on the plate lacking a required nutrient would include wild-type bacteria and all mutant bacteria except those mutant for the supplied nutrient, as these mutants would not be able to grow without the nutrient they cannot synthesize.

Question 6

You expose a tube of bacteria to ultraviolet radiation to induce mutations.You then spread the bacteria on a plate containing minimal media and wait until separate colonies form.Finally,you use replicate plating to transfer a print of this plate to an additional sterile plate containing minimal media plus a known required nutrient for the bacteria.Based on this protocol,colonies growing on the plate lacking a required nutrient would include what type of cells?

Accepted Answer

The answer of You expose a tube of bacteria to...

Question 7

If left untreated,syphilis infections go through four stages.The first stage is a sore called a chancre.The signs of the second stage are

Accepted Answer

The signs of the second stage of syphilis include rashes that may cover the entire body, sometimes a sore throat, and general aches and pains that appear to be flu-like. Option A describes the symptoms of the third stage of syphilis, option B is incorrect as many individuals with syphilis do experience symptoms, option D is not a recognized stage of syphilis, and option E describes symptoms of a different sexually transmitted infection (STI) such as gonorrhea.

Question 8

Which of the following statements about transformation is false?

Accepted Answer

Natural transformation is not an "accident" of plasmid biology; it is a natural process that some bacteria use to take up DNA from their environment, which can be beneficial for acquiring new traits.

Question 9

Prokaryotes reproduce rapidly and this allows genetic variation to spread quickly through a population.Two processes can create new variations in prokaryotic populations.Select the choice with those two processes.

Accepted Answer

The two processes that can create new variations in prokaryotic populations are genetic recombination and mutation. Genetic recombination involves the exchange of genetic material between two different prokaryotic cells, while mutation is a spontaneous change in the DNA sequence that can lead to new traits. Together, these two processes drive the rapid evolution and diversification of prokaryotic populations.

Question 10

Which of the following statements about generalized transduction is false?

Accepted Answer

The answer of Which of the following statements about generalized...

Question 11

Which of the following statements about Hfr cells and bacterial conjugation is false?

Accepted Answer

An Hfr cell cannot become an F^- cell because that designation refers to a specific combination of bacterial alleles that are not transferred during conjugation. The other statements are true: excision of the F plasmid from an Hfr cell can result in a partial diploid if some bacterial genes are included; transferred genes can replace equivalent genes in the recipient cell; F' plasmids contain some bacterial genes; and cells with integrated F' plasmids have two copies of some genes.

Question 12

The bacterium E coli has about 5000 genes.Assume a mutation rate of 1 in every one million genes.If you start with one bacterium that divides to produce two bacteria every 20 minutes,how many mutant E coli will there be after 10 hours?

Accepted Answer

One E coli divides to produce two bacteria every 20 minutes, which means in one hour (60 minutes), one bacterium will produce 2^3 = 8 bacteria. After 10 hours, one bacterium will produce 8^10 = 1.07 x 10^7 bacteria. The mutation rate is 1 in every 1 million genes, so each bacterium has a probability of 5 x 10^-6 of having a mutation in one of its genes. Therefore, the number of mutated bacteria after 10 hours is: 1.07 x 10^7 x 5 x 10^-6 = 53.5, which is approximately 5.4 x 10^16. Therefore, the best choice is C.

Question 13

Which of the following statements about tuberculosis (TB)is false?

Accepted Answer

HIV and TB are not transmitted in the same manner. TB is transmitted through the inhalation of droplets from an infected person's cough, sneeze, or spit, while HIV is transmitted through bodily fluids such as blood, semen, vaginal fluids, and breast milk.

Question 14

A microbiologist is conducting a research project on chemoautotrophs.This means that the investigator is examining certain aspects of a bacterium that

Accepted Answer

Chemoautotrophs are organisms that obtain their energy from the oxidation of inorganic molecules and use carbon dioxide as their carbon source. One example of this type of organism is a sulfur oxidizing bacterium, which obtains energy by oxidizing sulfur and uses carbon dioxide to build organic molecules. Therefore, choice A is the best answer.

Question 15

Tuberculosis remains a serious worldwide health problem due to all of the following except

Accepted Answer

The absence of MDR strains would not be a contributing factor to tuberculosis remaining a serious worldwide health problem. The other four options are all significant challenges in the fight against tuberculosis.

Question 16

Various techniques have been developed to isolate strains of bacteria carrying a particular mutation.In one,bacteria containing wild-type cells and cells of a desired mutant are grown on a medium lacking the nutrient for which the desired mutants are auxotrophic but containing the an antibiotic that only kills growing cells.In this environment,

Accepted Answer

Wild-type cells will die because they need the nutrient to grow and will be killed by the antibiotic. Mutant cells, being auxotrophic, do not grow in the absence of the nutrient and thus are not affected by the antibiotic.

Question 17

Which of the following statements about Hfr cells and bacterial conjugation is false?

Accepted Answer

The insertion of the F plasmid into the bacterial chromosome to produce an Hfr cell does not cause the loss of an equivalent portion of the chromosome. Instead, the F plasmid becomes integrated into the chromosome, and the resulting Hfr cell carries the entire chromosome along with the integrated F plasmid.

Question 18

Which of the following statements about bacterial conjugation is false?

Accepted Answer

The F plasmid undergoes rolling circle replication to produce a single-stranded copy, which is then transferred through the conjugation bridge to the recipient cell. The recipient cell then uses its own complementary strand to create a double-stranded plasmid.

Question 19

Plasmids are distinguished from bacterial chromosomes in that

Accepted Answer

Plasmids are small, circular DNA molecules found in bacteria that are physically separate from chromosomal DNA and typically carry only a few genes, unlike bacterial chromosomes, which are larger, usually circular (not linear as in eukaryotes), and contain the majority of the organism's genetic information.

Question 20

Which of the following events is least likely to result in a genetic change in a bacterium?

Accepted Answer

Pilus formation is the process by which a bacterium produces a thin, hair-like molecule on its surface that is used for attachment to other cells or surfaces. Although pilus formation may affect the way in which a bacterium interacts with other cells, it does not involve the transfer of genetic material and is therefore unlikely to result in a genetic change in the bacterium. On the other hand, conjugation, specialized transduction, generalized transduction, and natural transformation are all mechanisms by which bacteria can transfer genetic material between cells, and therefore are more likely to result in a genetic change.

Quiz 28: Prokaryotes

Streptococcus mutans one of the bacteria that can cause the loss of tooth enamel in humans.The metabolic process that this particular species of bacteria uses that can result in enamel breakdown is

Which of the following statements about sexually transmitted diseases (STDs) is false?

Which of the following statements about specialized transduction is false?

If left untreated,syphilis infections go through four stages.The first stage is a sore called a chancre.The signs of the second stage are

Which of the following statements about transformation is false?

Prokaryotes reproduce rapidly and this allows genetic variation to spread quickly through a population.Two processes can create new variations in prokaryotic populations.Select the choice with those two processes.

Which of the following statements about generalized transduction is false?

Which of the following statements about Hfr cells and bacterial conjugation is false?

The bacterium E coli has about 5000 genes.Assume a mutation rate of 1 in every one million genes.If you start with one bacterium that divides to produce two bacteria every 20 minutes,how many mutant E coli will there be after 10 hours?

Which of the following statements about tuberculosis (TB) is false?

A microbiologist is conducting a research project on chemoautotrophs.This means that the investigator is examining certain aspects of a bacterium that

Tuberculosis remains a serious worldwide health problem due to all of the following except

Which of the following statements about Hfr cells and bacterial conjugation is false?

Which of the following statements about bacterial conjugation is false?

Plasmids are distinguished from bacterial chromosomes in that

Which of the following events is least likely to result in a genetic change in a bacterium?