bio 102 unit 3 practice quiz

Fruit flies normally produce two types of antimicrobial peptides (defensin and drosomycin). Mutant fruit flies were generated that produced no antimicrobial peptides, defensin only, or drosomycin only. Wild-type flies and the mutant flies were then tested for survival after infection with Neurospora crassa fungi. What statement about these data is true?

Drosomycin protects fruit flies from N. crassa infections to a higher degree than does defensin.

Which of the three types of viruses shown in the figure above would you expect to include glycoproteins as part of their overall structure? (one is hexagon thingy, two is sphere thingy, three is that monster leg thing like from toy story)

II only

Why do some scientists believe that RNA, rather than DNA, was the first genetic material?

RNA has both information storage and catalytic properties.

Suppose a B cell is unable to perform alternative splicing. What consequence will this have in regards to the immune response of the B cell?

The B cell will make a limited number of antigen receptors.

Two prokaryotes are shown in the figure that have additional cellular membranes within the plasma membrane. What functions could the respiratory membranes and the thylakoid membranes provide?

The respiratory membrane allows a functional electron transport chain and oxidative phosphorylation of ATP.

Which of the following responses correctly lists the order of events in a generalized viral replicative cycle?

The virus enters the cell, host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA.

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

The plants would develop the typical symptoms of TMV infection.

Which of the following statements accurately describes plant virus infections?

They are spread via the plasmodesmata.

Which of the following statements correctly describes viruses?

They cannot reproduce without a host cell.

Which of the following statements correctly describes adenoviruses?

They contain DNA surrounded by a capsid.

Septic shock, a systemic response including high fever and low blood pressure, is a response to

certain bacterial infections.

Innate immunity and adaptive immunity are both _____.

characteristics of all vertebrate animals

Which of the following describes an organism that oxidizes inorganic substances to obtain energy that is used, in part, to fix CO2 from the atmosphere?

chemoautotrophs

Which of the following is a defining characteristic that all protocells or vesicles had in common?

a surrounding membrane or membrane-like structure

Mammals have Toll-like receptors (TLRs) that can recognize a kind of macromolecule that is absent from vertebrates but present in/on certain groups of pathogens, including viral

double-stranded RNA.

Which of the following steps has NOT yet been accomplished by scientists studying the origin of life?

formation of protocells that use DNA to direct the polymerization of amino acids

Which of the following processes can be effective in preventing the onset of viral infection in humans?

getting vaccinated

The complement system is a

group of antimicrobial proteins that act together in a cascading manner.

In the figure above, at the arrow marked II, what enzyme is being utilized?

host cell DNA polymerase

Innate immunity

is activated immediately upon infection.

Adaptive immunity depends on

pathogen-specific recognition.

Which of the following describes an organism that obtains energy from light?

phototroph only

The earliest organisms were most likely __________.

prokaryotic

On early Earth, what substance is hypothesized to have played a key role to facilitate the formation of polymers of amino acids, polymers of RNA, and vesicles?

sand, rock, or clay

Secondary immune responses upon a second exposure to a pathogen are due to the activation of

memory cells.

The cells and signaling molecules that initiate inflammatory responses are

the mast cells and the histamines.

According to scientists' hypotheses, prokaryotes most likely evolved prior to eukaryotes because

the oldest fossilized cells resemble prokaryotes.

The eyes and the respiratory tract are both protected against infections by

the secretion of lysozyme onto their surfaces.

Antibodies are made up of

two heavy chains and two light chains.

Please use the following information to answer the question(s) below. A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from bacteriophages and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan.In which feature(s) should you be able to locate a complete chromosome of this bacterium?1. nucleolus2. pili3. endospore4. nucleoid

3 and 4, so the endospore and nucleoid

In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA, referred to as the Baltimore requirements. The table below shows the results of testing five viruses (A−−E) for nuclease sensitivity, the ability of the viral genome to act as an mRNA, and the presence (+) or absence (-) of each virus's own polymerase. Based on the table above, which virus meets the requirements for a bacteriophage?

A

Emerging viruses arise by __________. mutation of existing viruses the spread of existing viruses to new host species the spread of existing viruses more widely within their host species All of the listed responses are correct.

All of the listed responses are correct.

Which secretion is not a barrier that prevents pathogens from entering the body? True or false? The leukocytes of the innate immune system are B cells, macrophages, and neutrophils. How do cells involved in the innate immune response detect the presence of pathogens? Which of the following cells can engulf a pathogen? Which of the following statements best describes the role of mast cells in the inflammatory response? Which of the following events occurs first when a wound that breaks the skin has occurred? The site of inflammation may become swollen due to the increased numbers of cells and fluids at the site and painful due to signals from pain receptors.

Antigens, (those are foreign molecules that initiate an immune response) False, (leukocytes of the innate immune system are mast cells, macrophages, and neutrophils) Leukocytes recognize unique molecules on pathogens. (such as the amino acid N-formylmethionine in bacteria. receptor binding=activation of the innate immune response) Macrophages They release chemicals that dilate blood vessels near the wound site, allowing blood components to enter the region from the bloodstream. Platelets release proteins that form clots and decrease bleeding. True

Which of the following is likely the greatest impact that organisms have ever had on Earth?

Early cyanobacteria released oxygen to Earth's atmosphere during the water-splitting step of photosynthesis.

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most challenging and would have the greatest impact on our understanding if we were able to answer it?

How did RNA sequences come to carry the code for amino acid sequences?

You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent .I. Treat the substance with nucleases that destroy all nucleic acids and then determine whether it is still infectious. II. Filter the substance to remove all elements smaller than what can be easily seen under a light microscope. III. Culture the substance by itself on nutritive medium, away from any plant cells. IV. Treat the sample with proteases that digest all proteins and then determine whether it is still infectious.If you already knew that the infectious agent was either bacterial or viral, which treatment listed above would allow you to distinguish between these two possibilities?

III. Culture the substance by itself on nutritive medium, away from any plant cells.

Suppose there is a phagocytic cell in which the pH inside the lysosome is significantly higher than normal. What outcome regarding phagocytosis is most likely to occur?

Pathogens will be able to enter the cell but will not be able to be broken down.

Part complete A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have __________.

T4 protein and T4 DNA

Suppose you get a cut on your finger, and bacteria enter your skin through the cut. What would be the immediate response by your immune system?

The complement system would be activated.

Which of the following statements correctly describes the lysogenic cycle of lambda (λλ) phage?

The phage genome replicates along with the host genome.

A plant that has been raised in a sterile environment shows symptoms of a viral infection. How would you explain this?

The viral infection was acquired by vertical transmission, ("Vertical transmission" refers to the inheritance of a viral infection from a parent)

How could this drug prevent infection in someone who is exposed to the flu or could shorten the course of flu in an infected patient (the reasons for which it is prescribed)? Match the terms in the left column to the appropriate blanks in the sentences on the right. Not all terms will be used.

There are 16 different types of hemagglutinin, a protein that helps the virus attach to host cells, and 9 types of neuraminidase, an enzyme that helps release new virus particles from infected cells, which can then invade new cells. Without neuraminidase, infectionis is suspected to be limited to one round of replication, rarely enough to cause disease.

Please use the following information to answer the question(s) below. A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from bacteriophages and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan.Adherence to the intestinal lining by this bacterium is due to its possession of

a capsule.

Which of the following statements correctly describes the best predictor of how much damage a virus causes?

ability of the infected cell to undergo normal cell division

In 2009, which of the following did scientists discover was possible on early Earth?

abiotic synthesis of RNA monomers

Which of these is NOT part of insect immunity?

activation of natural killer cells

The following question(s) are based on the observation that several dozen different proteins comprise the prokaryotic flagellum and its attachment to the prokaryotic cell, producing a highly complex structure.If the complex protein assemblage of the prokaryotic flagellum arose by the same general processes as those of the complex eyes of molluscs (such as squids and octopi), then

ancestral versions of this protein assemblage were either less functional or had different functions from modern prokaryotic flagella.

Please use the following information to answer the question below. Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O2 reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O2. Consider the colonial aquatic cyanobacterium Anabaena, whose heterocytes are described as having "a thickened cell wall that restricts entry of O2 produced by neighboring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates." Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are two "strategies" that nitrogen-fixing prokaryotes might use to protect these enzymes from oxygen?

be obligate anaerobes and package these enzymes in specialized cells or compartments that inhibit oxygen entry

Juan is a 5-year-old boy and recently recovered from the chickenpox. He returned to kindergarten and found out that his friend Tram had chickenpox too. Normally chickenpox is very infectious, but Juan did not acquire it again. Why was Juan protected from a second exposure to chickenpox?

because his immune system now has immunological memory

The nucleic acid of a virus particle is enclosed in a protein coat. What is this protein coat called?

capsid

Complete the replicative cycle of a virus with a single-stranded genome that can function as mRNAmRNA. Drag the appropriate labels to their respective targets. Not all labels will be used.

capsid proteins, glycoproteins, viral genome, complementary strand, new viral genome

The number of major histocompatibility complex (MHC) protein combinations possible in a given population is enormous. However, an individual in that diverse population has a far more limited array of MHC molecules because

each of the MHC genes has a large number of alleles, but each individual only inherits two for each gene.

Which of the following describes an organism that obtains both carbon and energy by ingesting prey?

heterotroph and chemotroph

An inflammation-causing signal released by mast cells at the site of an infection is (are)

histamine

The herpesviruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others.If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection?

interference with new viral replication in preexisting cases

Suppose that a mosquito has been internally infected by a potentially pathogenic fungus. What will help protect it from the infection?

its antimicrobial peptides

On early Earth, more than 4 billion years ago, environmental conditions were very different from those today because

only early Earth was intensely bombarded by large rocks and ice from space.

HIV uses which of the following processes to synthesize a DNA strand using its RNA genome as a template?

reverse transcription

Several scientific laboratories across the globe are performing research concerning the origin of life on Earth. Suppose one of these laboratories conducts abiotic experiment(s) to test the potential for hydrogen bonding between various nucleic acids and amino acids. Which of the following results of such experiments are most consistent with our current understanding of Earth's first genetic systems?

rna amino acid is highest

Which photograph in the figure shows the cellular structure observed in species such as Staphylococcus epidermis, Staphylococcus aureus, and Streptococcus pneumoniae?

spherical