A Quiz On AP Bio For Pros Ch 29 Quiz

1.

Which of these is the best description of a virus?

A.

A noncellular living organism
B.

One of the smallest bacteria known
C.

A member of the kingdom Virusae
D.

A cell at the boundary between living and nonliving things
E.

Chemical complexes of RNA or DNA protected by protein

Correct Answer
E. Chemical complexes of RNA or DNA protected by protein

Explanation
A virus can be described as chemical complexes of RNA or DNA protected by protein. Viruses are not considered living organisms because they lack the ability to reproduce and carry out metabolic processes on their own. They require a host cell to replicate and can cause diseases in humans, animals, and plants. The genetic material of a virus can be either RNA or DNA, and it is surrounded by a protein coat that provides protection. This description accurately captures the nature of a virus and distinguishes it from other options like bacteria or noncellular living organisms.

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2.

The innermost portion of a virus's structure is made up of

A.

A membranous envelope.
B.

Both DNA and RNA.
C.

Either DNA or RNA.
D.

A protein capsid.
E.

A protein spore coat.

Correct Answer
C. Either DNA or RNA.

Explanation
The innermost portion of a virus's structure can be either DNA or RNA. This is because viruses can have either DNA or RNA as their genetic material, but not both. The genetic material is surrounded by a protein capsid, which provides protection to the viral genome. The membranous envelope and protein spore coat are not typically found in viruses, and therefore, are not the correct answer.

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3.

Which statement is true about prokaryotes?

A.

They contain a nucleus.
B.

They lack ribosomes.
C.

They usually lack a cell wall.
D.

They do not divide by mitosis.
E.

They contain a single circular DNA molecule as the genetic material.

Correct Answer
E. They contain a single circular DNA molecule as the genetic material.

Explanation
Prokaryotes are unicellular organisms that lack a nucleus and membrane-bound organelles. Instead, their genetic material is found in a single circular DNA molecule, known as a plasmid, which is located in the cytoplasm. This DNA molecule contains all the necessary genetic information for the prokaryote's survival and replication. Therefore, the statement "They contain a single circular DNA molecule as the genetic material" is true for prokaryotes.

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4.

Prokaryotae are now divided into the

A.

Archaea and cyanobacteria.
B.

Bacteria and cyanobacteria.
C.

Photosynthetic bacteria and chemosynthetic bacteria.
D.

Archaea and bacteria.
E.

Autotrophs and heterotrophs.

Correct Answer
D. Archaea and bacteria.

Explanation
The correct answer is archaea and bacteria. Prokaryotae, also known as prokaryotes, are a group of organisms that lack a nucleus and membrane-bound organelles. They are divided into two main domains: archaea and bacteria. Archaea are known for their ability to survive in extreme environments, while bacteria are more diverse and can be found in various habitats. This division reflects the genetic and biochemical differences between these two groups of prokaryotes.

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5.

A bacteriophage is a virus that attacks only bacteria as its host cells.

A.

True
B.

False

Correct Answer
A. True

Explanation
A bacteriophage is a type of virus that specifically targets and infects bacteria. Unlike other viruses that can infect a wide range of host organisms, bacteriophages are highly specific to bacteria. They attach to the surface of bacterial cells, inject their genetic material, and take over the bacterial machinery to replicate themselves. This process eventually leads to the destruction of the bacterial cell. Therefore, the statement that a bacteriophage attacks only bacteria as its host cells is true.

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6.

An environmental change, such as exposure to ultraviolet light, may cause a lysogenic bacterium to enter a lytic cycle.

A.

True
B.

False

Correct Answer
A. True

Explanation
Exposure to ultraviolet light can indeed trigger a lysogenic bacterium to enter a lytic cycle. Ultraviolet light is known to cause DNA damage, which can disrupt the lysogenic cycle and activate the lytic cycle. In the lytic cycle, the bacteriophage (virus) replicates within the host bacterium and ultimately causes the host cell to burst, releasing new viral particles. This response to environmental change helps the bacterium survive and adapt to its surroundings.

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7.

One of the most effective ways of controlling a viral disease in animals is to use vaccines.

A.

True
B.

False

Correct Answer
A. True

Explanation
Vaccines are a proven and effective method for controlling viral diseases in animals. Vaccines work by stimulating the immune system to produce antibodies that can fight off the virus. When animals are vaccinated, they develop immunity to the specific virus, making them less susceptible to infection. This helps in preventing the spread of the disease and reducing the severity of symptoms in infected animals. Vaccination programs have been successful in controlling various viral diseases in animals, such as rabies, distemper, and foot-and-mouth disease. Therefore, the statement that using vaccines is one of the most effective ways of controlling viral diseases in animals is true.

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8.

Probably the most important means of gaining new genetic material for prokaryotic evolution is sexual recombination.

A.

True
B.

False

Correct Answer
B. False

Explanation
Sexual recombination is not a means of gaining new genetic material for prokaryotic evolution. Prokaryotes, such as bacteria, reproduce asexually through binary fission, where the parent cell divides into two identical daughter cells. In prokaryotes, genetic material can be transferred horizontally through processes like conjugation, transformation, and transduction, but these mechanisms do not involve sexual recombination. Sexual recombination is a characteristic of eukaryotes, where genetic material from two parents is combined to create offspring with new genetic combinations.

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9.

A Gram stain will turn a gram-negative cell purple and a gram-positive cell red.

A.

True
B.

False

Correct Answer
B. False

Explanation
The given statement is false. In a Gram stain, a gram-negative cell will turn pink or red, while a gram-positive cell will turn purple or blue. This staining technique is based on the differences in the cell wall structure of bacteria. Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, which allows the crystal violet stain to be washed away more easily, resulting in the pink/red color. Gram-positive bacteria have a thicker peptidoglycan layer, which retains the crystal violet stain, giving them a purple/blue color.

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