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Microbiology Test 2 Ch. 5, 6, and 7
Terms in this set (89)
Microorganisms are given names that describe the environments in which they live. Match each bacterial name to the correct environmental parameter.growth above pH 9? growth in high salt?growth at high pressure?
alkaliphile, halophile, barophile
growth above pH 9?
growth in high salt?
growth at high pressure?
Which of the following is true of all biofilms?
they are attached to surfaces
Shown is the autotroph Nostoc. Evaluate the following claim: Nostoc is a pathogen.
Match the prefix with the appropriate description of different forms of energy-yielding metabolism: preformed organic molecules are acquired from outside the cell, broken down for carbon, and the carbon reassembled to make biomass
Match the prefix with the appropriate description of different forms of energy-yielding metabolism: CO2 is fixed and assembled into organic molecules
Match the prefix with the appropriate description of different forms of energy-yielding metabolism: high absorption captures energy
Match the prefix with the appropriate description of different forms of energy-yielding metabolism: chemical electron donors are oxidized
Match the prefix with the appropriate description of different forms of energy-yielding metabolism: inorganic molecules donate electrons
Match the prefix with the appropriate description of different forms of energy-yielding metabolism: organic molecules donate electrons
Phases of growth curve
2. Lag Phase
3. Exponential Phase
4. Stationary Phase
5. Death Phase
First portion of growth curve w/ no significant increase in cell.
-Cells are adjusting to new environment
-Cells are preparing to divide, creating new structure/elongating
-Cells are recovering/repairing damage from transfer
Second portion of growth curve with MAXIMUM increase in cell #
Exponential Phase (Log Phase)
third portion of growth curve with no significant increase OR decrease in cell #
-nutrients and space become limited
-waste begins to accumulate, makes environment less favorable for cell division
-equal # of cell deaths and cell division cells are alive
final portion of growth curve w/ maximum (exponential) decrease in cell #
-complete depletion of nutrients/resources
-waste accumulates and becomes toxic to cells
A typical E. coli cell does not rely on any growth factors. Which of the following is true?
Complex or defined but will grow faster on complex
Clinical diagnostic microbiologists use an array of media types to aid in identification of bacterial pathogens.
Differential media expose biochemical differences among species that grow equally well, while selective media expose growth differences among species.
The human body harbors both aerobic and anaerobic microbes.
Which of these statements are correct about the identity of a pathogen?
Only some pathogens need specific growth factors.
This plate contains MacConkey medium, which only allows the growth of Gram-negative bacteria. How can MacConkey medium be classified?
Both differential and selective
If the doubling time for a bacterial species is 30 minutes and there are two cells at the start, what is the population size after 2 hours?
What happens to a microbial cell in an environment below its optimal temperature?
Membrane fluidity decreases.
The growth rate decreases.
Two microbiologists, Chris and Alex, are given a patient sample and asked to enumerate the number of bacteria present. Chris performs a dilution series on a spread plate and estimates 1.5 × 105 bacterial cells/ml of the original sample. Alex performs a direct count with a Petroff-Hausser chamber and estimates 2 × 105 cells/ml in the original sample. Why might the spread plate technique give a smaller count?
Alex counted both viable and nonviable cells.
Alex counted the individual cells in chains of cells, but these clumps give rise to single colonies.
Often when plates are prepared, the numbers of colonies are too numerous to count (TNTC), so scientists do tenfold dilutions and prepare agar plates. On the basis of the countable colony numbers underneath each plate, approximately how many cells were initially plated on the 10-3 dilution plate?
How are biofilms and endospores similar?
Formation of both is influenced by the environment.
Both may be resistant to antibiotics.
An organism lacks an enzyme necessary to synthesize the amino acid alanine. Which of the following is true?
the organism must have alanine in the medium to grow
If you are trying to culture a microbe isolated from the environment, your best choice is to use a defined medium.
An organism has cysteine as a growth factor. What can we infer from this?
The organism cannot synthesize its own cysteine.
Cysteine is usually present in this organism's normal environment.
Bacteria in rice fields commonly oxidize ammonia, gaining electrons from inorganic molecules.
Many Pseudomonas species only grow in environments that contain sugar and oxygen.
Cyanobacteria generate oxygen and use carbon dioxide as a carbon source.
How are cells able to maintain order in a disordered world?
The energy-generating biochemical reactions that break down organic food molecules are what type of reactions?
Bacterial pathogens most commonly use this class of metabolism.
Some bacterial pathogens only cause disease when injected into tissue and are not able to grow or cause disease on skin or other surface-exposed regions. One example is Clostridium tetani (tetanus). Which type of metabolism would you expect these pathogens to use?
ATP is formed during respiration by which process(es)?
Which of the following generates the proton motive force (PMF)?
electron transport system
Energy-yielding and energy-generating reactions are linked by which molecule composed of a base, a sugar, and three phosphoryl groups?
How can scientists use bacterial metabolism to diagnose disease?
-Pathogens metabolize sugars in different ways. Not all pathogens use the same pathways.
-Not all pathogens ferment glucose.
Which process do cells use to complete metabolism without consuming oxygen?
How do organisms with small genomes, such as Escherichia coli, carry out so many different biochemical reactions?
Common energy carriers allow energy to interchange between many different chemical reactions.
Enterobacter aerogenes produces 2,3-butanediol from pyruvate.
Pseudomonas aeruginosa shuttles electrons to oxygen.
Bacillus cereus gains 2 ATP per glucose molecule.
Which process is responsible for the oxygen in the air we breathe?
Free-living bacteria make less ATP than that made by mitochondria for which of the following reasons?
Bacterial cells use the proton motive force to eject antibiotics and toxic compounds from the cytoplasm.
Bacterial cells spend energy on maintaining ion balance and nutrient uptake.
How does carbon fixation on Earth predominantly occur?
by microbes in the ocean
There are no photosynthetic causes of disease.
What would happen if all the enzymes in a cell went on strike?
Cells would die.
Most reactions would not proceed.
Which of these processes use the proton motive force (PMF)?
ion gradient maintenance in extreme pH environments
bacterial flagellar rotation
Many microbial cells release O2 gas as a waste product. Why is it released and not used?
Oxygen is a highly reactive substance and must either be detoxified or released
This enzyme is required for photolithotrophic and photoautotrophic organisms to produce new proteins, carbohydrates, and cellular structures. It is found in the Calvin cycle and may be the most important enzyme on Earth. It is the most abundant enzyme on Earth. What is the name of this enzyme?
How do living cells maintain order in a disordered (or entropic) world?
To overcome entropy, all life on Earth uses ENERGY originally from the SUN. Enzymes build complex molecules and create structure inside of the cells, DECREASING local entropy. Local entropy, or the entropy present in the cell, is always LESS THAN entropy outside of the cell. Cells exist an an ORDERED fashion, while EXTRACELLULAR REGIONS are disorganized, or have high entropy.
Nitrate poisoning causes methemoglobinemia. While nitrate and nitrite are naturally produced in the human intestine, high concentrations in food and/or water can cause this condition. Which of the following examples describe how nitrate contamination may happen?
- High pH reduces nitrate to nitrite, which then oxidizes hemoglobin. Oxidized hemoglobin is unable to transport oxygen effectively.
- An infant's stomach pH is greater than that of an adult's, allowing nitrate to be even more poisonous.
- Lithotrophic bacteria in soils oxidize ammonium from fertilizers into nitrate.
Farmer John has begun using natural rhizobia-containing fertilizers on his soybean crop in an effort to reduce his fertilizer usage. This natural additive contains bacteria. What benefit do these bacteria give to John's crops?
- Rhizobia are symbiotic bacteria that live with plants, enhancing their growth.
- This natural fertilizer supplies nitrogen, a limiting nutrient, to the crops.
Which of the following describe fermentation?
- Electrons are donated to pyruvate to regenerate NAD+.
- an incomplete form of digestion
- the least efficient form of metabolism
Which of these organisms are performing anaerobic respiration?
- Salmonella enterica donates electrons to tetrathionate (S4O62-).
- Pseudomonas aeruginosa donates electrons to nitrate.
Can cells start the TCA cycle with an intermediate product?
Yes, but only if the cell had transports to bring these molecules in
Enzymes are responsible for storing energy released from biochemical reactions.
The final electron acceptor in respiration is an organic molecule.
Which membrane-embedded enzymes transfer electrons through the membrane and to the final electron acceptor?
Compounds tagged with an acetyl-CoA group will be sent to which process in the cell?
the TCA cycle
How many molecules of ATP do bacterial cells gain from glycolysis?
Which type of reaction produces antibiotics in Streptomyces bacteria?
Which food types cannot be catabolized by human cells?
complex plant fibers
Where in the human body would you find lithotrophs?
How can scientists use bacterial metabolism to diagnose disease?
Pathogens metabolize sugars in different ways. Not all pathogens use the same pathways.
Not all pathogens ferment glucose.
What is the term for inorganic food molecules serving as electron donors in energy-yielding metabolic reactions?
Which of the following accurately describes the entropy changes that occur in living cells and their surroundings?
Entropy decreases in cells but increases in their surroundings.
An organism gains energy using sugars as an electron donor and Fe+3 as an electron acceptor. This type of metabolism is an example of
Which statement is accurate about the role of cellular enzymes?
They control where and when reactions occur.
Which of the following accurately describes how catabolism yields energy?
Food molecules are catabolized in many steps, each yielding a small amount of energy that a few common energy carriers capture.
Which of the following molecules can donate electrons in metabolic reactions?
Which reaction pairs both have positive free energy changes?
ATP production and reduction of NAD+
During glycolysis __________ is oxidized to __________ and _________ is reduced to ____________.
glucose; pyruvate; NAD+; NADH
In both fermentation and respiration,
NAD+ is regenerated from NADH.
Which metabolic pathway is assessed by diagnostic media to identify pathogens?
organic acid respiration
Before feeding into the TCA cycle, pyruvate is first converted to
If an organism uses elemental sulfur as its final electron acceptor at the end of its electron transport system, what compound will be produced?
As electrons are passed down an electron transport system,
Protons are pumped across a membrane.
The equation CO2 + 4 H2 → 2 H2O + CH4 is a summary of an organism's respiration. Which of the following is true?
H2 is the initial electron donor.
During photosynthesis, the light energy is initially captured by
Photosynthesis of sugar can occur without light if the organism is supplied with
ATP and NADPH.
Cyanobacteria produce which of the following molecules, which humans require for respiration?
Which of the following in an example of an anabolic reaction?
Which of the following is often a limiting nutrient for plants?
How many CO2 molecules are needed to form one glucose molecule during photosynthesis?
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