3.2.2 Binary Fission and Viruses

What is the process called in which prokaryotic cells divide?

• Mitosis

• Binary fission

• Meiosis

• Budding

Answer explanation

Prokaryotic cells divide through a process called binary fission, where the cell grows and then splits into two identical daughter cells. Mitosis and meiosis are processes for eukaryotic cells, while budding is a form of asexual reproduction.

During binary fission, what happens to the circular DNA in prokaryotic cells?

• It is destroyed

• It is replicated

• It is converted into linear DNA

• It remains unchanged

Answer explanation

During binary fission, prokaryotic cells replicate their circular DNA to ensure that each daughter cell receives a complete copy. Therefore, the correct answer is that the circular DNA is replicated.

What is the role of plasmids during binary fission in prokaryotic cells?

• They are discarded

• They are replicated

• They are converted into proteins

• They are used as energy sources

Answer explanation

During binary fission, plasmids are replicated along with the bacterial chromosome. This ensures that each daughter cell receives a copy of the plasmids, which can carry beneficial genes.

How many daughter cells are produced from one prokaryotic cell after binary fission?

• One

• Two

• Three

• Four

Answer explanation

During binary fission, a prokaryotic cell divides into two identical daughter cells. Therefore, the correct answer is two, as one prokaryotic cell produces two daughter cells.

What is the main difference between binary fission and viral replication?

• Binary fission involves a host cell

• Viral replication involves cell division

• Binary fission does not require a host cell

• Viral replication does not involve DNA

Answer explanation

The main difference is that binary fission is a method of asexual reproduction in prokaryotes that does not require a host cell, while viral replication relies on a host cell to reproduce and propagate.

Why do viruses not undergo cell division?

• They lack DNA

• They are non-living

• They are too small

• They have no cytoplasm

Answer explanation

Viruses are considered non-living because they cannot reproduce independently. They lack the cellular machinery required for cell division, relying instead on host cells to replicate.

What happens to the viral nucleic acid after it is injected into the host cell?

• It is destroyed by the host cell

• It replicates the virus particles

• It becomes part of the host DNA

• It remains inactive

Answer explanation

After the viral nucleic acid is injected into the host cell, it replicates the virus particles, leading to the production of new viruses. This process is essential for the virus to propagate and infect other cells.

In binary fission, what is the variability in the number of plasmid copies in daughter cells?

• There is no variability

• It is always the same as the parent cell

• It can vary between daughter cells

• It is always zero

Answer explanation

In binary fission, plasmid distribution can be uneven, leading to variability in the number of plasmid copies between daughter cells. Thus, the correct answer is that it can vary between daughter cells.

Which of the following is NOT a characteristic of binary fission?

• Involves replication of circular DNA

• Produces genetically identical cells

• Requires a host cell

• Involves division of cytoplasm

Answer explanation

Binary fission is a form of asexual reproduction that does not require a host cell; it occurs in prokaryotes like bacteria. The other options describe characteristics of binary fission accurately.

What is the primary function of the host cell in viral replication?

• To destroy the virus

• To replicate viral particles

• To provide nutrients to the virus

• To convert viral RNA to DNA

Answer explanation

The primary function of the host cell in viral replication is to replicate viral particles. The virus hijacks the host's cellular machinery to produce new virus copies, rather than destroying the virus or converting RNA to DNA.