Question 1

The family Staphylococcaceae respire using oxygen as the terminal electron acceptor,although some can reduce nitrate to nitrite.

Accepted Answer

Staphylococcaceae are known as aerobic bacteria as they require oxygen for respiration. However, some species have been found to have the ability to reduce nitrate to nitrite under anaerobic conditions as a means of generating energy.

Question 2

Terminal electron acceptors used by Desulfotomaculum include sulfate and sulfite,converted to hydrogen sulfide.

Accepted Answer

Desulfotomaculum is a genus of bacteria that are able to use sulfate and sulfite as terminal electron acceptors in anaerobic respiration, which results in the production of hydrogen sulfide. This process is known as sulfate reduction.

Question 3

The organisms that causes toxic shock syndrome is ______.

Accepted Answer

Staphylococcus aureus is the organism that causes toxic shock syndrome. It produces a toxin known as toxic shock syndrome toxin-1, which causes the symptoms of toxic shock syndrome.

Question 4

Some species of Streptococcus,when grown on blood agar,produce an incomplete hemolysis with the formation of a greenish zone around the colony; this is referred to as ______.

Accepted Answer

Alpha-hemolysis is characterized by an incomplete hemolysis of red blood cells on blood agar. The greenish zone around the colony is indicative of the partial breakdown of hemoglobin and the formation of methemoglobin. Beta-hemolysis is a complete hemolysis, resulting in a clear zone around the colony, while gamma-hemolysis is the absence of hemolysis. Since the Streptococcus species produces an incomplete hemolysis, it is most likely to be alpha-hemolysis.

Question 5

Which of the following is associated with dental caries?

Accepted Answer

Dental caries is primarily associated with Streptococcus mutans, which is a bacteria commonly found in the oral cavity. This bacteria feeds on sugars and produces acid, which can erode tooth enamel and lead to cavities.

Question 6

Members of the genus Lactobacillus

Accepted Answer

Members of the genus Lactobacillus are normal flora of the human body in mouth, intestinal tract, and vagina.

Question 7

Bacillus species are facultative anaerobes that can use nitrate as a terminal electron acceptor.

Accepted Answer

Bacillus species are indeed facultative anaerobes, which means they can switch between aerobic and anaerobic respiration depending on the availability of oxygen. They are also known to use nitrate as a terminal electron acceptor in anaerobic respiration.

Question 8

Members of the genus Streptococcus carry out __________ fermentation.

Accepted Answer

Members of the genus Streptococcus carry out homolactic fermentation, which produces predominantly lactic acid as the end product. This is in contrast to heterolactic fermentation, which produces a mixture of lactic acid, ethanol, and other products, and butanediol fermentation, which produces butanediol and a small amount of acid. Mixed acid fermentation also produces a variety of acids, including acetic acid, formic acid, and lactic acid, but is not typically associated with Streptococcus species.

Question 9

Species of Veillonella are always parasites of warm-blooded animals and are never found as part of the normal biota.

Accepted Answer

This statement is false. While some species of Veillonella are indeed parasitic, others are part of the normal biota, particularly in the oral cavity and gastrointestinal tract of humans and other animals.

Question 10

Bacteria in the genus ________ are sulfate and sulfite reducers.

Accepted Answer

The answer of Bacteria in the genus ________ are sulfate...

Question 11

It has been determined from several human disease samples that bacteria exist that are 16S rRNA sequenced to be Gram-positive,but morphologically double-membraned like Gram-negatives,therefore requiring a new class.

Accepted Answer

The statement is true. These bacteria, which have been found in human disease samples, are called "Gram-variable" or "diderm" bacteria and are now classified as a separate phylum known as "Candidatus Bipolaricaulota".

Question 12

Some species of Streptococcus,when grown on blood agar,produce a complete hemolysis with the formation of a clear zone around the colony; this is referred to as ______.

Accepted Answer

Beta-hemolysis is the complete lysis of RBCs around the colony, resulting in the formation of a clear zone. Alpha-hemolysis is partial lysis, resulting in a greenish coloration around the colony, while gamma-hemolysis is no lysis, resulting in no change in the agar.

Question 13

Which of the following is used in the production of buttermilk and cheese?

Accepted Answer

Lactococcus lactis is used in the production of buttermilk and cheese.

Question 14

Which of the following will grow in broth with 6.5% salt?

Accepted Answer

Enterococcus faecalis is a halotolerant bacterium that can grow in high salt concentrations such as 6.5% salt. Streptococcus mutans and Lactococcus lactis are not typically halotolerant, and may not grow in such high salt concentrations.

Question 15

Although Desulfotomaculum species stain Gram- bacteria and are correctly placed in the low G + C
Firmicutes.

Accepted Answer

The answer of Although Desulfotomaculum species stain Gram- bacteria and...

Question 16

Which of the following is a normal skin resident?

Accepted Answer

Staphylococcus epidermidis is a normal resident of the skin microbiota.

Question 17

Endospore-forming Gram-positive bacteria are found primarily in ________ habitats.

Accepted Answer

Endospore-forming Gram-positive bacteria are commonly found in soil habitats. While they can also be found in other habitats, such as freshwater and marine environments, soil is their primary habitat.

Quiz 23: Firmicutes: The Low G-C Gram-Positive Bacteria