MCB 150 Test 1 with Answers 2025-
2026 Updated.
If the simple classification of an organism as a plant or animal is no longer sufficient, why are newly
discovered organisms still assigned genus and species names? - Answer Genus and species names
designate how organisms are related to each other by determining what group that organism falls into.
Even though the means of classification is different than it once was, the genus and species system has
been adapted to the modern system of classification and is still a useful way to organize living things.
Explain the benefits of compartmentalization as a cell increases in size, including a consideration of the
chemistry within the cell. - Answer As cells increase in size there is more room for complex cellular
reactions to occur, but there is also more need of organization of these cellular functions.
Compartmentalization does just that, it allows the cell to be more organized in this larger and more
complex environment.
A research colleague has provided you with a single cell to identify. Briefly describe the steps you would
take to determine which domain this cell would most likely belong to. - Answer I would sequence the
16s rRNA gene from this cell, then compare this sequence to the known 16s rRNA sequences to see
which domain the sequence from the unknown cell most closely resembles.
Based on the revised tree of life as shown on the previous page, which type of Eukaryote would you
expect to have a small subunit rRNA sequence the most similar to an Archael species, and why? -
Answer Diplomonads. Each fork in the tree represents an evolutionary divergence. The fork for the
Diplomonad group is closer to the fork where the Archaea split off than the other Eukaryotic forks.
Therefore, the Diplomonads have a more recent common ancestor with the Archaea than do the other
branches of the Eukaryotic portion of the tree and will have a more similar small subunit rRNA
sequence.
Cells have the ability to take up fragments of DNA from their extracellular surroundings through a
process called transformation. With this information, propose a (very general) hypothesis for how a
bacterial cell might acquire DNA from a eukaryotic species through horizontal gene transfer. Do not
attempt to get technical with your answer; a general proposal is sufficient. - Answer If a eukaryotic cell
dies or bursts open it could release its DNA into the environment. This could happen for a number of
reasons; perhaps a bacterial cell invades and kills a eukaryotic cell, or a virus infects the eukaryotic cell
and the cell dies. This cell death could release the eukaryotic DNA into the environment and a bacterium
, could take up the DNA via transformation. Once the eukaryotic DNA is inside the bacterial cell it could
get incorporated into the genome of the bacterium.
Which one of the following statements about the domains of life is incorrect?
E. coli is an example of an organism in the archael domain.
The typical size of bacteria and archaea is approximately 1-10 microns.
Incorrect The chromosomes of bacteria and archaea are typically circular.
In most molecular processes, archaea are more related to humans than to bacteria.
Structurally, archaea more closely resemble bacteria than eukaryotes. - Answer A
Which of the following statements about archae is correct?
Archaea perform their complex biochemical functions in distinct compartments called organelles.
Archaea share similar structural features with bacteria, but are not bacteria.
Archaea are the only types of organisms currently believed to fall into the classification of prokaryotes.
Archaea typically have multiple circular chromosomes as their genetic material.
Archaea typically have multiple linear chromosomes as their genetic material. - Answer B
Which of the following statements about horizontal gene transfer is incorrect?
Horizontal gene transfer can allow for quick evolutionary jumps.
2026 Updated.
If the simple classification of an organism as a plant or animal is no longer sufficient, why are newly
discovered organisms still assigned genus and species names? - Answer Genus and species names
designate how organisms are related to each other by determining what group that organism falls into.
Even though the means of classification is different than it once was, the genus and species system has
been adapted to the modern system of classification and is still a useful way to organize living things.
Explain the benefits of compartmentalization as a cell increases in size, including a consideration of the
chemistry within the cell. - Answer As cells increase in size there is more room for complex cellular
reactions to occur, but there is also more need of organization of these cellular functions.
Compartmentalization does just that, it allows the cell to be more organized in this larger and more
complex environment.
A research colleague has provided you with a single cell to identify. Briefly describe the steps you would
take to determine which domain this cell would most likely belong to. - Answer I would sequence the
16s rRNA gene from this cell, then compare this sequence to the known 16s rRNA sequences to see
which domain the sequence from the unknown cell most closely resembles.
Based on the revised tree of life as shown on the previous page, which type of Eukaryote would you
expect to have a small subunit rRNA sequence the most similar to an Archael species, and why? -
Answer Diplomonads. Each fork in the tree represents an evolutionary divergence. The fork for the
Diplomonad group is closer to the fork where the Archaea split off than the other Eukaryotic forks.
Therefore, the Diplomonads have a more recent common ancestor with the Archaea than do the other
branches of the Eukaryotic portion of the tree and will have a more similar small subunit rRNA
sequence.
Cells have the ability to take up fragments of DNA from their extracellular surroundings through a
process called transformation. With this information, propose a (very general) hypothesis for how a
bacterial cell might acquire DNA from a eukaryotic species through horizontal gene transfer. Do not
attempt to get technical with your answer; a general proposal is sufficient. - Answer If a eukaryotic cell
dies or bursts open it could release its DNA into the environment. This could happen for a number of
reasons; perhaps a bacterial cell invades and kills a eukaryotic cell, or a virus infects the eukaryotic cell
and the cell dies. This cell death could release the eukaryotic DNA into the environment and a bacterium
, could take up the DNA via transformation. Once the eukaryotic DNA is inside the bacterial cell it could
get incorporated into the genome of the bacterium.
Which one of the following statements about the domains of life is incorrect?
E. coli is an example of an organism in the archael domain.
The typical size of bacteria and archaea is approximately 1-10 microns.
Incorrect The chromosomes of bacteria and archaea are typically circular.
In most molecular processes, archaea are more related to humans than to bacteria.
Structurally, archaea more closely resemble bacteria than eukaryotes. - Answer A
Which of the following statements about archae is correct?
Archaea perform their complex biochemical functions in distinct compartments called organelles.
Archaea share similar structural features with bacteria, but are not bacteria.
Archaea are the only types of organisms currently believed to fall into the classification of prokaryotes.
Archaea typically have multiple circular chromosomes as their genetic material.
Archaea typically have multiple linear chromosomes as their genetic material. - Answer B
Which of the following statements about horizontal gene transfer is incorrect?
Horizontal gene transfer can allow for quick evolutionary jumps.
