Question 1

A useful technique for comparing different bacterial species based on if they are susceptible to infection by the same virus is called

Accepted Answer

Phage typing involves testing different bacterial species for susceptibility to a panel of bacteriophages (viruses that infect bacteria). By observing which phages are able to infect a particular bacterial species, scientists can identify similarities or differences between different strains or species of bacteria. This technique is particularly useful for identifying bacterial strains that may be responsible for outbreaks of infectious disease.

Question 2

Rickettsiae and Chlamydiae are unusual in that they

Accepted Answer

Rickettsiae and Chlamydiae are obligate intracellular parasites, meaning they must live inside other living cells to survive and reproduce.

Question 3

Polyacrylamide gel electrophoresis is used to separate

Accepted Answer

Polyacrylamide gel electrophoresis is commonly used to separate proteins by size. DNA sequencing would use a different technique, such as Sanger sequencing or Next-Generation sequencing.

Question 4

The 16S ribosomal subunit is used to study evolutionary relatedness because

Accepted Answer

Ribosomes have evolved very slowly, which means that differences between different species can be traced back to their common ancestor. The 16S subunit is also conserved and present in all prokaryotes and some eukaryotes, making it a useful tool for studying evolutionary relationships.

Question 5

In phage typing,bacteria that are lysed by the same type of bacteriophage are thought to be

Accepted Answer

Bacteria that are lysed by the same type of bacteriophage are thought to be more closely related to one another because phage typing is based on the principle that different strains of bacteria have different surface antigens that are recognized by different bacteriophages. Therefore, bacteria that are susceptible to the same bacteriophage are likely to have similar surface antigens, which suggests that they are more closely related to one another.

Question 6

In DNA hybridization experiments,DNA from two closely related organisms will show

Accepted Answer

DNA from two closely related organisms will have a high percentage of complementary base pairing, leading to a high degree of annealing.

Question 7

How do lateral gene transfer and symbiosis complicate both the three domain and five kingdom treelike structure? Where do viruses,viroids and prions fit in today's taxonomy? Are they classified based on phylogeny or morphology?

Accepted Answer

The answer of How do lateral gene transfer and symbiosis...

Question 8

Organisms that degrade organic molecules to methane belong to the domain

Accepted Answer

The answer of Organisms that degrade organic molecules to methane...

Question 9

If an organism contains 13% adenine in its DNA,its GC content is

Accepted Answer

In a DNA molecule, the amount of adenine (A) is equal to the amount of thymine (T), and the amount of guanine (G) is equal to the amount of cytosine (C). Given that adenine is 13%, thymine will also be 13%, making A+T = 26%. Since the total DNA content must equal 100%, the remaining percentage is for G+C, which is 100% - 26% = 74%.

Question 10

In a bacterial species with multiple chromosomes

Accepted Answer

In bacterial species with multiple chromosomes, there is evidence for spindles that ensure all the daughter cells receive one of each chromosome. This is different from the typical process of binary fission where the chromosomes are simply replicated and segregated into two daughter cells.

Question 11

To classify new microbes,modern genetic techniques are employed. Why would the evolutionary relatedness of genes (genetic homology)be more useful than morphology? How are ribosomal RNAs used to study evolutionary relationships among organisms?

Accepted Answer

The answer of To classify new microbes,modern genetic techniques are...

Question 12

Viruses are not assigned to any Kingdom because

Accepted Answer

Viruses are not considered alive because they cannot replicate on their own and do not have the ability to carry out metabolism or cellular respiration. Therefore, they do not fit into any of the traditional Kingdoms of living organisms.

Question 13

In the three domain classification system

Accepted Answer

In the three-domain system, Archaea and Eukarya are more closely related to each other than to Bacteria, based on genetic and biochemical evidence.

Question 14

What is a species? How are species determined for bacteria and plants/animals? Discuss whether you believe that the species concept is better than identifying microbes based on their ecological niche (habitat,functions,etc.)or based on phylogenetic/evolutionary relationships.

Accepted Answer

The answer of What is a species? How are species...

Question 15

Genetic homology determines evolutionary relationships among organisms based on

Accepted Answer

Genetic homology refers to the similarity of DNA between two organisms. By comparing DNA sequences, scientists can determine the degree of relatedness between species and construct evolutionary relationships. This is because DNA sequences are inherited from ancestral species and reflect the history of how species have evolved over time.

Option A is partially correct, as ribosomal RNA can also be used to determine evolutionary relationships through a process called molecular phylogenetics.

Option C is not always reliable, as morphological similarities can be misleading, especially in distantly related organisms that may have evolved convergent traits.

Option D is vague and not specific enough to be a correct choice.

Question 16

Which of the following criteria is not commonly used to classify bacteria?

Accepted Answer

The shape of ribosomes is not commonly used to classify bacteria. Morphology, staining characteristics, and biochemical characteristics are commonly used for classification.

Quiz 9: An Introduction to Taxonomy: the Bacteria