Question 1

The correct sequence of reagents used in the Gram stain technique is ____. ​

Accepted Answer

The correct sequence of reagents used in the Gram stain technique is crystal violet, iodine, alcohol, and safranin. This sequence allows for the differentiation of bacterial cell walls based on the presence or absence of a thick layer of peptidoglycan. Gram-positive bacteria have a thick peptidoglycan layer, which retains the crystal violet-iodine complex and appears purple under the microscope. Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, which is disrupted by the alcohol treatment, causing the crystal violet-iodine complex to be washed out. The addition of safranin stains the Gram-negative bacteria pink/red, allowing for their visualization.

Question 2

Cyanobacteria are ____. ​

Accepted Answer

Cyanobacteria are photosynthetic organisms, which means they are capable of using light as a source of energy to synthesize organic compounds from carbon dioxide and water. Therefore, they are classified as photoautotrophs.

Question 3

The lipopolysaccharides are associated with the ____ membrane of Gram- ____ bacteria. ​

Accepted Answer

Lipopolysaccharides are found in the outer membrane of Gram-negative bacteria. Gram-positive bacteria do not have an outer membrane.

Question 4

If the peptidoglycan layer is between two plasma membranes in an organism, that organism is ____. ​

Accepted Answer

Gram-negative bacteria have a peptidoglycan layer that is between two plasma membranes, resulting in a distinct cell wall structure compared to Gram-positive bacteria. Archaea may have cell walls made of different components, such as pseudopeptidoglycan or S-layer proteins, but they do not have a peptidoglycan layer between two plasma membranes. Chemoautotrophic and eukaryotic are not related to cell wall structure.

Question 5

The major structural component of bacterial cell walls is ____. ​

Accepted Answer

Peptidoglycan is the primary component of bacterial cell walls, consisting of long chains of alternating subunits of N-acetylglucosamine and N-acetylmuramic acid cross-linked by short peptide chains.

Question 6

Arrange the following layers from most external to most internal.
1 = Cell membrane
2 = Capsule
3 = Cell wall

Accepted Answer

The capsule is the most external layer, followed by the cell wall, and then the cell membrane is the most internal layer. Therefore, the correct order is 2, 3, 1.

Question 7

Bacterial flagella ____. ​

Accepted Answer

Bacterial flagella are indeed smaller and simpler than eukaryotic flagella. They consist of a filamentous protein called flagellin, arranged in a helical structure that propels the bacteria forward in a whip-like manner. They are not powered by calcium ions or microtubules, and not all bacteria have flagella.

Question 8

An organism that obtains its energy from sunlight is a(n)____. ​

Accepted Answer

An organism that obtains its energy from sunlight is called a phototroph, which is described in option E. Autotrophs are organisms that can make their own food using inorganic compounds, heterotrophs obtain energy by consuming organic compounds, and chemotrophs obtain energy by breaking down chemicals. Auxotrophs are organisms that require specific nutrients that they cannot synthesize themselves.

Question 9

The three domains of life are ____.

Accepted Answer

The three domains of life are Archaea, Bacteria, and Eukarya, as determined by genetic sequencing and biochemical differences. Option A is incorrect since viruses are not considered living organisms, while options B and C do not accurately reflect the current classification system. Option D uses outdated terms (Archaebacteria and Eubacteria) and does not include the third domain, Eukarya.

Question 10

DNA in prokaryotes is found in ____.

Accepted Answer

In prokaryotes, DNA is primarily located in the nucleoid, a region within the cell that lacks a surrounding membrane, and can also be found in plasmids, which are small, circular DNA molecules separate from the chromosomal DNA.

Question 11

Most of the bacteria that cause human disease are ____. ​

Accepted Answer

Most bacteria that cause human disease are chemoheterotrophs, meaning they obtain energy and carbon from organic molecules. They cannot produce their own food and rely on consuming other living or dead organisms.

Question 12

The genome of most prokaryotes consists of ____.

Accepted Answer

The answer of The genome of most prokaryotes consists of...

Question 13

A Gram-positive bacterium is characterized by the ____. ​

Accepted Answer

Gram-positive bacteria are characterized by having a thick peptidoglycan cell wall. This cell wall is responsible for retaining the crystal violet stain used in the Gram staining procedure. Gram-negative bacteria, on the other hand, have a thinner peptidoglycan layer and an outer membrane, which makes them more resistant to certain antibiotics and disinfectants.

Question 14

After performing a Gram stain on a mixed culture of Gram-positive and Gram-negative cells, you realize that you omitted the iodine step. What would you expect to see if you observed the slide under the microscope? ​

Accepted Answer

Without the iodine step, the crystal violet dye is not properly fixed in the cells. Both Gram-positive and Gram-negative cells will not retain the crystal violet and will appear pink after staining with safranin, the counterstain.

Question 15

An organism that obtains its carbon from CO₂ is a(n)____.

Accepted Answer

The answer of An organism that obtains its carbon from...

Question 16

Prokaryotes that are curved and comma-like are called ____. ​

Accepted Answer

Vibrios are curved and comma-like prokaryotes, while cocci are spherical, bacilli are rod-shaped, spirilla are helical or spiral-shaped, and sarcina are cuboidal-shaped.

Question 17

An organism that obtains its energy by oxidizing organic or inorganic substances is a(n)____.

Accepted Answer

Organisms that obtain their energy by oxidizing organic or inorganic substances are known as chemotrophs. This process is known as chemosynthesis, and it is the opposite of photosynthesis, which uses sunlight to create energy. Chemotrophs can be found in a variety of environments, including soil, deep-sea vents, and hot springs.

Question 18

Prokaryotes ____.

Accepted Answer

Prokaryotes lack a nucleus, which is a defining characteristic of eukaryotic cells.

Question 19

Prokaryotic ribosomes are composed of ____. ​

Accepted Answer

Prokaryotic ribosomes are composed of proteins and RNA, with 30S and 50S subunits combining to form the complete 70S ribosome.

Question 20

Prokaryotic cells generally reproduce by ____. ​

Accepted Answer

Prokaryotic cells reproduce by binary fission, which is a form of asexual reproduction where the cell divides into two nearly equal parts. Mutations, conjugation, transduction, and transformation are all processes that can bring about genetic diversification or exchange in prokaryotic cells, but they are not the primary means of reproduction.

Quiz 26: Prokaryotes and Viruses

The correct sequence of reagents used in the Gram stain technique is ____.

Cyanobacteria are ____.

The lipopolysaccharides are associated with the membrane of Gram- bacteria.

If the peptidoglycan layer is between two plasma membranes in an organism, that organism is ____.

The major structural component of bacterial cell walls is ____.

Arrange the following layers from most external to most internal. 1 = Cell membrane 2 = Capsule 3 = Cell wall

Bacterial flagella ____.

An organism that obtains its energy from sunlight is a(n) ____.

The three domains of life are ____.

DNA in prokaryotes is found in ____.

Most of the bacteria that cause human disease are ____.

The genome of most prokaryotes consists of ____.

A Gram-positive bacterium is characterized by the ____.

After performing a Gram stain on a mixed culture of Gram-positive and Gram-negative cells, you realize that you omitted the iodine step. What would you expect to see if you observed the slide under the microscope?

An organism that obtains its carbon from CO₂ is a(n) ____.

Prokaryotes that are curved and comma-like are called ____.

An organism that obtains its energy by oxidizing organic or inorganic substances is a(n) ____.

Prokaryotes ____.

Prokaryotic ribosomes are composed of ____.

Prokaryotic cells generally reproduce by ____.

Quiz 26: Prokaryotes and Viruses

The correct sequence of reagents used in the Gram stain technique is ____. ​

Cyanobacteria are ____. ​

The lipopolysaccharides are associated with the ____ membrane of Gram- ____ bacteria. ​

If the peptidoglycan layer is between two plasma membranes in an organism, that organism is ____. ​

The major structural component of bacterial cell walls is ____. ​

Arrange the following layers from most external to most internal. 1 = Cell membrane 2 = Capsule 3 = Cell wall

Bacterial flagella ____. ​

An organism that obtains its energy from sunlight is a(n) ____. ​

The three domains of life are ____.

DNA in prokaryotes is found in ____.

Most of the bacteria that cause human disease are ____. ​

The genome of most prokaryotes consists of ____.

A Gram-positive bacterium is characterized by the ____. ​

After performing a Gram stain on a mixed culture of Gram-positive and Gram-negative cells, you realize that you omitted the iodine step. What would you expect to see if you observed the slide under the microscope? ​

An organism that obtains its carbon from CO2 is a(n) ____.

Prokaryotes that are curved and comma-like are called ____. ​

An organism that obtains its energy by oxidizing organic or inorganic substances is a(n) ____.

Prokaryotes ____.

Prokaryotic ribosomes are composed of ____. ​

Prokaryotic cells generally reproduce by ____. ​

The correct sequence of reagents used in the Gram stain technique is ____.

Cyanobacteria are ____.

The lipopolysaccharides are associated with the membrane of Gram- bacteria.

If the peptidoglycan layer is between two plasma membranes in an organism, that organism is ____.

The major structural component of bacterial cell walls is ____.

Bacterial flagella ____.

An organism that obtains its energy from sunlight is a(n) ____.

Most of the bacteria that cause human disease are ____.

A Gram-positive bacterium is characterized by the ____.

After performing a Gram stain on a mixed culture of Gram-positive and Gram-negative cells, you realize that you omitted the iodine step. What would you expect to see if you observed the slide under the microscope?

An organism that obtains its carbon from CO₂ is a(n) ____.

Prokaryotes that are curved and comma-like are called ____.

Prokaryotic ribosomes are composed of ____.

Prokaryotic cells generally reproduce by ____.