Question 1

The plasma membrane of archaea is composed of a phospholipid bilayer.

Accepted Answer

The plasma membrane of archaea is unique because it is composed of ether lipids, with the hydrophobic tails being isoprenoids, rather than the ester-linked fatty acids found in the phospholipid bilayers of bacteria and eukaryotes.

Question 2

Bacterial metabolism is quite diverse and can range from heterotrophic individuals that are anaerobic to ones that use mitochondria to run cellular respiration.rev: 12_12_2013_QC_42367

Accepted Answer

Bacteria do not have mitochondria; they perform cellular respiration across their cell membrane.

Question 3

Which feature is lacking in the cell wall of archaea that will distinguish them from the bacteria?
A)peptidoglycan
B)phospholipids
C)proteins
D)polysaccharides
E)None of the answer choices are lacking in the cell walls of the archaea.

Accepted Answer

Peptidoglycan is a key component of bacterial cell walls, but it is absent in the cell walls of archaea. Instead, archaeal cell walls are composed of a variety of substances, including proteins, polysaccharides, and sometimes phospholipids. Therefore, the absence of peptidoglycan is the feature that distinguishes archaea from bacteria.

Question 4

Some 20th-century authors wrote that the earliest protocells would have to be autotrophs.This concept appears to be
A)correct,since heterotrophs would depend upon eating autotrophs.
B)correct,since life is not possible without ATP which is only available in living systems.
C)correct,since glycolysis and fermentation only occur after oxygen is present from photosynthesis.
D)incorrect,since the primordial soup could contain many preformed food molecules.
E)incorrect,since glycolysis and fermentation require complex enzymes for catalytic reactions.

Accepted Answer

The primordial soup theory suggests that early Earth had a rich mixture of organic compounds, providing preformed food molecules that early heterotrophic protocells could utilize.

Question 5

Biological evolution (the evolution of living cells)differs from chemical evolution (the evolution of the molecules that make living cells)in that biological evolution would have been possible only after the development of
A)a membrane.
B)nucleic acids.
C)enzymes.
D)a metabolic pathway.
E)RNA and enzymes.

Accepted Answer

A membrane is necessary for the formation of a self-contained cell, which is the basic unit of life. Without a membrane, molecules cannot be organized into a functional living system. While all of the other choices are also important for biological evolution, they would not have been possible without a membrane to contain and protect the necessary molecules.

Question 6

Which of the following organisms is considered a microbe?
A)bacteria
B)snail
C)eagle
D)oak tree
E)roundworm

Accepted Answer

Only bacteria are considered microbes.

Question 7

Which statement is NOT true about a protocell?
A)It would have contained DNA as its genetic material.
B)It would have been present before the development of a true cell.
C)It would have had a lipid and protein membrane surrounding it.
D)It would have contained a biochemical pathway for energy metabolism.
E)The hydrophilic heads of the membrane would have pointed outwards while the hydrophilic tails would have pointed inwards.

Accepted Answer

It is not necessarily true that a protocell would have contained DNA as its genetic material. Some theories suggest that early forms of life may have used RNA as their genetic material before the evolution of DNA.

Question 8

Which description best fits a chemoautotroph bacteria?
A)They reduce carbon dioxide to an organic compound by using energetic electrons derived from chemicals.
B)They reduce carbon dioxide to an inorganic compound by using energetic electrons derived from chemicals.
C)They run photosynthesis that uses solar energy to produce their own food.
D)They transfer electrons to sulfate,producing hydrogen sulfate.
E)All of the answer choices are descriptions of a chemoautotroph bacteria.

Accepted Answer

Chemoautotroph bacteria reduce carbon dioxide to an organic compound by using energetic electrons derived from chemicals.

Question 9

In a liquid environment,____ molecules will automatically form droplets called liposomes.
A)amino acid
B)protein
C)glucose
D)phospholipid
E)nucleic acid

Accepted Answer

Liposomes are formed from phospholipid molecules in a liquid environment. Amino acids, proteins, glucose, and nucleic acids do not form liposomes.

Question 10

A complex protein-rich cell shelters and supports the DNA genetic code,and the code is the blueprint for the cell proteins; thus is set the "chicken-or-the-egg" dilemma of which came first.This is probably solved by the discovery that
A)polypeptides and RNA could have evolved simultaneously.
B)reverse transcriptase can convert RNA back into DNA.
C)all DNA and protein can be distributed evenly inside and outside the nucleus.
D)some proteins are simply assemblages of guanine,cytosine,thymine,and adenine.
E)viruses can give rise to all of the cell molecules.

Accepted Answer

The discovery that polypeptides and RNA could have evolved simultaneously suggests that both DNA and proteins could have arisen together, resolving the chicken-or-the-egg dilemma. Reverse transcriptase converting RNA back into DNA, the distribution of DNA and protein within the cell, protein assemblages of nucleotides, and viruses giving rise to all cell molecules are not directly related to solving the dilemma between DNA and protein evolution.

Question 11

The central dogma of genetics states that DNA directs protein synthesis and that information flows from
A)protein $\rightarrow$ RNA $\rightarrow$ DNA
B)protein $\rightarrow$ DNA $\rightarrow$ RNA
C)RNA $\rightarrow$ protein $\rightarrow$ DNA
D)RNA $\rightarrow$ DNA $\rightarrow$ protein
E)DNA $\rightarrow$ RNA $\rightarrow$ protein

Accepted Answer

The central dogma of genetics describes the flow of genetic information as DNA being transcribed into RNA, which is then translated into protein.

Question 12

According to Fox's laboratory experiments,the protocell could have been composed
A)only of carbohydrates.
B)mostly of polypeptides.
C)of phospholipids.
D)of chitinous threads.
E)of protein and RNA.

Accepted Answer

The answer of According to Fox's laboratory experiments,the protocell could...

Question 13

What general feature is necessary to consider an organism a microbe?
A)small enough that a microscope is required to see them
B)multicellular
C)heterotrophic
D)sexual reproduction
E)use aerobic respiration for metabolism

Accepted Answer

The general feature necessary to consider an organism a microbe is that it is small enough that a microscope is required to see them. This is the defining characteristic of microbes, which include various types of bacteria, archaea, fungi, protists, and viruses.

Question 14

What feature enables the archaea to survive in harsh environments?
A)their plasma membranes and cell walls
B)their metabolism
C)the ability to form multicellular organisms
D)their reproductive capabilities
E)their nucleus

Accepted Answer

The archaea's plasma membranes and cell walls are designed to withstand extreme temperatures, pressures, pH levels, and salt concentrations, enabling them to thrive in harsh environments such as hot springs, deep-sea hydrothermal vents, and acidic marshes. Their unique membrane lipids composed of isoprene chains instead of fatty acids allow for structural stability in extreme environments, while their cell walls made of pseudopeptidoglycan provide protection against environmental stresses.

Question 15

Compare the domains of Archaea and Eukarya in regards to their features.

Accepted Answer

The answer of Compare the domains of Archaea and Eukarya...

Question 16

Which of these would have been most likely to develop only after the formation of a true cell?
A)autotroph
B)heterotroph
C)protocell
D)microsphere
E)proteinoid

Accepted Answer

The answer of Which of these would have been most...

Question 17

List the four stages that are thought to have led to the formation of the first cells.

Accepted Answer

The answer of List the four stages that are thought...

Question 18

Which term does NOT apply to the first protocell?
A)fermentation
B)autotrophic
C)membrane-bound
D)single-celled
E)self-replicating

Accepted Answer

Autotrophic refers to an organism that can produce its own food from inorganic sources, which is unlikely to apply to the first protocell as it would have been extremely primitive and likely relied on organic compounds present in its environment. The other four terms, fermentation, membrane-bound, single-celled, and self-replicating, are all reasonable characteristics for the first protocell.

Question 19

Which type of nutrition is believed to have come first?
A)autotrophic
B)heterotrophic
C)aerobic
D)photosynthetic
E)catalytic

Accepted Answer

Heterotrophic nutrition, where organisms obtain their nutrients from organic compounds, is believed to have come first in the evolution of life on Earth. This is because the earliest organisms did not have the ability to produce their own food through photosynthesis or chemosynthesis, and instead had to rely on consuming other organic matter.

Question 20

Which of the following is a benefit of microbes? A)break down organic molecules B)Various microbes help protect us from harmful microbes. C)aid in digestion D)synthesize vitamins K and B₁₂ E)All of the answer choices are benefits of microbes.

Accepted Answer

All of the answer choices are benefits of microbes. Microbes play an essential role in breaking down organic molecules, aiding in digestion, synthesizing vitamins, and various microbes help protect us from harmful microbes. Therefore, E - All of the answer choices are benefits of microbes is the correct answer.

Quiz 28: Viruses, bacteria, and Archaea

The plasma membrane of archaea is composed of a phospholipid bilayer.

Bacterial metabolism is quite diverse and can range from heterotrophic individuals that are anaerobic to ones that use mitochondria to run cellular respiration.rev: 12_12_2013_QC_42367

Which feature is lacking in the cell wall of archaea that will distinguish them from the bacteria?

Some 20th-century authors wrote that the earliest protocells would have to be autotrophs.This concept appears to be

Biological evolution (the evolution of living cells) differs from chemical evolution (the evolution of the molecules that make living cells) in that biological evolution would have been possible only after the development of

Which of the following organisms is considered a microbe?

Which statement is NOT true about a protocell?

Which description best fits a chemoautotroph bacteria?

In a liquid environment,____ molecules will automatically form droplets called liposomes.

A complex protein-rich cell shelters and supports the DNA genetic code,and the code is the blueprint for the cell proteins; thus is set the "chicken-or-the-egg" dilemma of which came first.This is probably solved by the discovery that

The central dogma of genetics states that DNA directs protein synthesis and that information flows from

According to Fox's laboratory experiments,the protocell could have been composed

What general feature is necessary to consider an organism a microbe?

What feature enables the archaea to survive in harsh environments?

Compare the domains of Archaea and Eukarya in regards to their features.

Which of these would have been most likely to develop only after the formation of a true cell?

List the four stages that are thought to have led to the formation of the first cells.

Which term does NOT apply to the first protocell?

Which type of nutrition is believed to have come first?

Which of the following is a benefit of microbes?