Biology II Exam 1

What are the two main ways in which a virus can spread to infect secondary sites in the human body?

In blood or lymph, via neurological tissue

The genome of HIV consists of

two single-stranded, plus-sense RNA molecules.

____ is a condition characterized by viruses freely circulating in the blood or lymph.

viremia

In ____ viral infections, a virus or its genome can be found in the host for long periods of time: years, decades, and sometime for the rest of the host's life.

persistant

A change in the phenotype of a lysogenic bacterium caused by the prophage is called ____ ____.

phage conversion

A change in the phenotype of a lysogenic bacterium caused by the prophage is called.

phage conversion

Prokaryotes may gain a selective advantage in their particular environments when ____ are transferred to them via conjugation.

plasmids

Gram-____ bacteria have a relatively thin peptidoglycan layer in their cell walls, and appear red after a Gram stain.

positive

What disease agents are infectious proteins that can cause transmissible spongiform encephalopathies?

prions

Carbon, nitrogen, phosphorus, sulfur, and other atoms are all recycled to the physical environment following the death of an organism through the action of:

prokaryotes and fungi

When outside of a host cell, an individual viral particle is known as a(n) ____

virion

Identify the disease agent that ranges in size from about 20-250 nm in diameter.

virus

Which of the following viruses uses the cellular machinery of a bacterium for its own replication?

Bacteriophage

Why is it difficult to classify influenza viruses based on their host?

Because there are four types of influenza viruses that can infect many different hosts (humans, birds, pigs, dogs, cats)

Some plasmids pick up antibiotic resistance genes and transfer these genes to other prokaryotes via which of the following?

Conjugation

How does HIV compromise the human immune system, allowing opportunistic infections to invade the body?

Infected CD4+ cells are killed until few are left.

What is the consequence of the destruction of CD4+ cells by HIV to the human body?

It is no longer defended against invading bacteria and viruses, leading to opportunistic infections.

Which scientist settled the argument over spontaneous generation?

Louis Pasteur

Which of the following statements regarding plasmids is not true?

Plasmids cannot be transferred to another bacteria.

Rank the following cells and particles in order according to size, with the smallest at the top and largest at the bottom.

Protein, T2 bacteriophage, Influenza virus, E. Coli bacterium, Eukaryotic cell

Viroids are infectious disease agents in plants that are composed solely of circular ____.

RNA

Choose the three types of persistent human viral infections based on the amount of virus present and when it is produced.

Slow, Chronic, Latent

Of the following list, which are the two most important types of cells killed by HIV?

T-helper cells, Macrophages

Which infectious agents are composed solely of RNA?

Viroids

A(n) ____ disease is a disease that appears in the population for the first time, or that spreads to a new geographical area.

emerging

Most viruses have a capsid that is ____ or ____ in terms of its basic structure and symmetry.

helical, icosahedral

After the immune system can no longer control HIV, it starts killing cells expressing the CD4 antigen. Of those cells, the most important types are the T-____ cells which coordinate the immune response and the ____ which engulf pathogenic bacteria.

helper, macrophages

A disease that was prominent in the past, and whose incidence suddenly increases after a period of low incidence, is called a ____ disease.

re-emerging

In the mutualistic symbiosis exhibited by nitrogen-fixing bacteria and plants, the plant receives ____ from the bacteria and the bacteria receive ____ from the plant.

nitrogen, sugar

In the mutualistic symbiosis exhibited by nitrogen-fixing bacteria and plants, the plant receives ____ from the bacteria and the bacteria receive ____ from the plant.

nitrogen, sugars

The french microbiologist Louis Pasteur

refuted the idea of spontaneous generation.

The genome of HIV consists of two identical ____ - stranded, ____ - sense RNA molecules.

single, plus

In the mutualistic symbiosis between nitrogen-fixing bacteria and plants, what benefit do the plants provide the bacteria?

sugars

Phage conversion is

the change in the phenotype of a lysogenic bacterium caused by the prophage.

Transmissible spongiform encephalopathies (TSEs) cause

the development of numerous small cavities in the brain as neurons die.

Which of the following statements best describes viral genomes?

they may be circular or linear, single-stranded or double-stranded, and composed of DNA or RNA

DNA can enter bacterial cells via ____, a process that uses viral vectors.

transduction

Which of the following are atypical viral shapes that have so far been observed only in Archaeal viruses?

two-tailed, spindle-shaped, bottle-shaped

In the Baltimore classification of viruses, there are ____ groups of viruses and every known virus can be placed in only one such group based on the way it ____ its genome.

7, replicates

Which of the following is characteristic of the lytic cycle?

A large number of phages is released at a time.

Although bacteria and archaea are very similar, they differ in several key areas. Which of the following is a key difference in their plasma membrane?

Archaeal membrane lipids contain ether bonds.

Which of the following are sexually transmitted diseases caused by bacteria?

Chlamydia, Syphilis, Gonorrhea

Viruses that contain ____ as their genetic material are often assigned to species group; the same is not true of viruses with ____ as their genetic material.

DNA, RNA

True or false: The role of bacteria and archaea in the cycling of carbon is very limited.

False, prokaryotes play a crucial role in the cycling of carbon as they decompose dead organic material.

Choose all the conventional systematic groups that are also used to classify viruses.

Family, Genus, Order

What is the effect of the initial acute disease episode after infection with an HSV-1 or HSV-2?

Formation of painful blisters at the site of infection

HIV is transmitted when contaminated bodily fluids come into contact with a ____, or directly enter tissues.

HIV is transmitted when contaminated bodily fluids come into contact with a mucous membrane, or directly enter tissues.

The transfer of genes between different species is known as ____ gene transfer.

Horizontal

Which of the following elements is not generally recycled by prokaryotes?

Hydrogen

After the initial acute disease (painful blisters) subsides due to an immune response, where can HSV-1 and HSV-2 be found?

In the nuclei of sensory neurons that innervate the site of infection

Which of the following statements is true about prokaryotic cells?

They lack functional compartmentalization, but may possess invaginated regions of the plasma membrane that function in cellular respiration.

Both bacteria and archaea have cell walls, but the cell walls are chemically different between the two. Which describes the cell wall of the Archaea?

They lack peptidoglycan.

A(n) ____ viral infection involves the rapid replication of the virus, often at the site of infection, which leads to sudden symptom onset.

acute

Bacteria and ____ are collectively referred to as prokaryotes

archaea

Viruses with a two-tailed structure, with a bottle shaped structure, and with a spindle-shaped structure have all been observed in

archaea

Prokaryotes that obtain their energy from inorganic CO2 are ____ whereas those that obtain at east some of their carbon from organic molecules such as glucose are ____.

autotrophs, heterotrophs

Bacteria-infecting viruses are also known as which of the following?

bacteriophage

The classification of viruses based on genome replication is known as the ____ classification after the scientist that first proposed it.

baltimore

Viruses are obligate ____ parasites.

intracellular

Regarding bacteriophage, during which type of cycle does the phage enter a latent phase, allowing it to be replicated with the host cell?

lysogenic

In order to study viruses in the environment, scientists isolate nucleic acids from an environmental sample, sequence them, and use computers to assemble genomes and compare them to known sequences in databases. This approach is known as _______.

metagenomics

____ involves isolating DNA from an environmental sample, sequencing it, and comparing it to known sequences in DNA databases.

metagenomics

This type of Staphylococcus aureus has been acquired in hospital settings for some time and is now being observed in community-acquired infections.

methicillin-resistant

Early taxonomies used characteristics which were easily observable or detectable with the use of a ____ to classify prokaryotes.

microscope