Micro textbook questions

Which organism is NOT correctly matched to its energy source?

photoautotroph - CO2

What is the fate of fatty acids in cellular respiration?

Oxidized in the Krebs cycle

Which of the following statements about photophosphorylation is not true?

It requires CO2

A bacterium such as Pseudomonas uses nitrate as a final electron acceptor in an electron transport system. All the below statements are true EXCEPT

they require light

Microorganisms that catabolize sugars into ethanol and CO2 gas would most likely be categorized as ________.

alcohol fermenters

Which of the following is the best definition of fermentation?

the partial oxidation of glucose with organic molecules serving as electron acceptors

What is the purpose of fermentation?

to regenerate NAD+ from NADH

Which type of metabolic diversity contains most pathogens?

chemoheterotroph

Why is reduction the term used to describe the gain of an electron?

The electron acceptor’s net charge decreases.

Which of the following statements regarding redox reactions is true?

Redox reactions involve an oxidation reaction coupled with a reduction reaction.

How does a noncompetitive inhibitor reduce an enzyme’s activity?

The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site.

What would be the likely outcome if you increased the concentration of substrate for an enzyme in the presence of a noncompetitive inhibitor?

No change in enzyme activity would be observed.

Which of the following matches enzyme components with their correct definition and/or function?

Coenzymes are organic cofactors important to enzyme activity.

Researchers are developing a ribozyme that cleaves the HIV genome. This pharmaceutical agent could be described as

an RNA molecule capable of catalysis.

When bacteria are inoculated into a new sterile nutrient broth, their numbers don’t begin to increase immediately. Instead, there is a lag phase that may last for an hour or even several days. Why don’t bacterial numbers increase immediately?

The bacteria must adjust to the nutrient content in the new medium, synthesizing necessary amino acids, growth factors, and enzymes.

A chemostat is continuous culture system that is designed to promote and prolong exponential growth and prevent bacteria from entering stationary phase. How might this work?

Chemostats provide a continued source of fresh nutrients and remove wastes and dead bacterial cells.

Which of the following methods would be most appropriate for gathering data to plot a bacterial growth curve throughout the four phases?

plate count

Which of the following elements is NOT correctly matched with its cellular function?

phosphorus – used for production of carbohydrates.

Most bacteria grow best at pH

7

Which of the following is an organic growth factor?

vitamin B1

A sample of milk is tested for its bacterial content in a plate count assay. A 1 ml sample of the milk is diluted in a 1:10 serial dilutions. 1ml of the third dilution tube is plated in a pour plate. After incubation, the plate has 54 colonies, indicating that the original milk sample contained ________ cells per milliliter.

54,000

How many cells are produced after binary fission?

2

Which of the following chemicals is required in very small amounts by cells?

Vitamin B1

How many generations (doublings) occur in 3 hours if the generation time is 30 minutes?

6

Three bacterial cells were inoculated into a culture medium with a generation time of 60 minutes. Assuming no lag phase takes place, how many cells are there after 5 hours?

96

The U.S. Food and Drug Administration convention when performing pour or spread plate counts is to count only plates with ________ colonies.

25-250

During the initiation step of translation in prokaryotes, the fMet-charged tRNA binds to which site of the ribosome before elongation begins?

P site

How does the ribosome know if the entering charged tRNA is correct?

The anticodon on the tRNA base pairs to the codon on the mRNA.

What kind of bond is formed when two amino acids join together?

peptide bond

Which statement about DNA replication is FALSE?

DNA ligase adds nucleotides to the lagging strand.

The molecule that seals the gaps between the pieces of DNA in the lagging strand is

DNA ligase

Which of the following build(s) new strands of DNA?

DNA polymerases

How many net molecules of ATP are produced after the breakdown of one glucose molecule in prokaryotes?

38

How many net molecules of ATP are produced after the breakdown of one glucose molecule in eukaryotes?

36

How many net molecules of ATP are produced during glycolysis?

2

What are the most important molecules produced during the Krebs cycle?

NADH and FADH2

Which of the following statements about enzymes is false?

Enzymes are very inefficient in their reactions.

What is the most basic and least effective mechanism of generating ATP in cells?

Substrate-level phosphorylation