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BIO SCI 101 > Exam 2 > Flashcards

Exam 2 Flashcards

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Biology 101 flashcards
1
Q

The phylogenetic classification of bacteria is based on

A

rRNA sequences

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2
Q

In the scientific name Vibrio cholera, Vibrio is the

A

genus

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3
Q

You discovered a unicellular organism that lacks a nucleus. You suspect the organism is in the group

A

bacteria

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4
Q

Into which group would you place a photosynthetic organism that lacks a nucleus and has a thin peptidoglycan wall surrounded by an outer membrane?

A

gram-negative bacteria

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5
Q

Which of the following best describes the enteric bacteria (a bacterial group found primarily in the intestines of humans)?

A

facultatively anaerobic gram-negative rods

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6
Q

Which of the following bacteria is gram-negative?

A

Escherichia

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7
Q

Which of the following is not correct regarding Escherichia coli?

A

doesn’t require or use O2, but can tolerate it

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8
Q

Which of the following genera include bacteria with stalks?

A

Caulobacter

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9
Q

Which of the following have their flagella (sometimes called axial filaments) located entirely between the cytoplasmic membrane and the outer membrane?

A

spirochetes

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10
Q

Cyanobacteria

A

produce O2

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11
Q

Bacteria that naturally exhibit bioluminescence have been found in which of the following genera?

A

Vibrio

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12
Q

Bacterial sensing of cell density is called:

A

quorum sensing

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13
Q

Which of the following statements about the causative agent of Rocky Mountain spotted fever is FALSE?

A

It is gram-positive

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14
Q

Bacteria of the genus Bdellovibrio:

A

prey on Gram-negative bacteria

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15
Q

In which of the following regions in the host bacterium are you most likely to find Bdellovibrio?

A

periplasm

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16
Q

Members of the genus Neisseria cause which of the following human diseases?

A

Gonorrhea

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17
Q

Members of the genus Rhizobium:

A

grow symbiotically in root nodules of legumes where they fix nitrogen

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18
Q

Bacteria that can perform both nitrogen fixation and oxygenic photosynthesis:

A

Cyanobacteria

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19
Q

Which genus contains anaerobic endospore formers?

A

Clostridium

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20
Q

Bacilli are:

A

Gram-positive, aerobic, spore forming rods

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21
Q

Bacillus thuringiensis:

A

is used as a biological insecticide

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22
Q

Staphylococcus and Streptococcus can usually be differentiated by microscope examination because of:

A

cell arrangement

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23
Q

The characteristic most notable regarding the Mycoplasmas is that they:

A

lack peptidoglycan

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24
Q

The characteristic most notable regarding the Mycobacteria is that they:

A

have unusual outer membrane, made of unusual lipids

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25
Q

Which of the following bacteria produce mycelia?

A

Streptomyces

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26
Q

Streptomyces are important because they:

A

make antibiotics

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27
Q

Gram-positive bacteria that form symbiotic association with roots of woody plants and can fix atmospheric nitrogen:

A

Frankia species

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28
Q

Saccharomyces cerevisiae are often nicknamed:

A

baker’s yeast, budding east , and brewer’s yeast

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29
Q

Plasmodium falciparum, that causes malaria is a/an:

A

eukaryote

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30
Q

African sleeping sickness is caused by:

A

Trypanosoma brucei

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31
Q

Which of the following are NOT eukaryotes?

A

Candida, Entamoeba, Giardia, and Trypanosoma are all eukaryotes

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32
Q

T/F Most bacteria reproduce by binary fission.

A

true

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33
Q

Microorganisms are at their most uniform in terms of chemical and physiological properties during this growth phase:

A

exponential

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34
Q

Which of the following are a reason(s) for the decline in cell numbers during the death phase?

A

Accumulation of toxic waste materials, and Depletion of nutrients and O2

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35
Q

If bacteria have a doubling time of 20 min and you start with two bacterial cells, how many cells will you have after 1 hour?

A

16

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36
Q

Which of the following is an advantage of the standard plate count?

A

determines the number of viable cells

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37
Q

Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate count. How many viable and culturable cells were in the original sample?

A

36 per milliliter

38
Q

A microbiologist is testing the drinking water for a municipality. What would be the best method for testing the purified water?

A

membrane filtration

39
Q

T/F Thermophiles prefer to grow at high temperatures.

A

true

40
Q

Most bacteria grow best at pH:

A

7

41
Q

The term aerotolerant anaerobe refers to an organism that:

A

does not use oxygen but tolerates it

42
Q

T/F Enzyme catalase protects the cells from toxic forms of oxygen.

A

true

43
Q

A culture medium consisting of agar, peptone, and beef heart extract is a:

A

complex medium

44
Q

T/F An isolated colony on a streak plate contains millions (or even billions) of identical cells all arising from one initial cell.

A

true

45
Q

The sugar found in DNA is:

A

deoxyribose

46
Q

If 20% of nucleotides in the DNA of a particular organism contain thymine, estimate the percentage of cytosine that is present in the DNA.

A

30%

47
Q

Which of the following is not a complementary base pair found in DNA molecules?

A

Adenine-Uracil

48
Q

Each chromosome has one or more site(s) where replication begins.

A

origin

49
Q

During replication, which enzyme unwinds the two strands of the DNA molecule from one another?

A

Helicase

50
Q

An enzyme that makes covalent bonds between Okazaki fragments in the lagging strand of DNA being replicated is:

A

DNA ligase

51
Q

During DNA replication, the template sequence 3’-ATGGCTT -5’ will direct the synthesis of what sequence:

A

5’-TACCGAA -3’

52
Q

Which of the following statements is FALSE?

A

DNA replication proceeds in only one direction around the bacterial chromosome

53
Q

Which of the following nitrogenous bases is found in RNA but not in DNA?

A

Uracil

54
Q

T/F Genes code for proteins only.

A

false

55
Q

T/F To start the synthesis RNA polymerase requires a primer.

A

false

56
Q

RNA polymerases require which of the following elements to transcribe DNA?

A

DNA template, ribonucleotides

57
Q

Which of the following is NOT a product of transcription?

A

a new strand of DNA

58
Q

T/F During transcription, RNA pol joins ribonucleotides in 3’ to 5’ direction?

A

false

59
Q

A bacterial __________ is the non-transcribed region of the DNA to which RNA polymerase binds to initiate transcription.

A

promoter

60
Q

Coding sequence of the gene is 5’ AAA TCG GGC GTA CCT 3’. What will be the sequence of the corresponding mRNA?

A

5’AAA UCG GGC CUA CCU 3’

61
Q

The genetic code is translated in groups of how many bases?

A

three

62
Q

The genetic code is said to be __________ because more than one codon will specify a particular amino acid.

A

degenerate

63
Q

The portion of the tRNA molecule that forms hydrogen bonds with the codon on the mRNA is called the:

A

anticodon

64
Q

Which molecules deliver amino acids to ribosomes during translation?

A

a.a.tRNA

65
Q

For translation the start codon is often 1 which codes for 2 :

A

1-AUG, 2-methionine

66
Q

Peptide bonds between amino acids are formed in which process?

A

translation

67
Q

How many different termination codons (stop codons) are used in translation?

A

3

68
Q

T/F In eukaryotes gene expression is always “coupled” (i.e. transcription and translation occur at the same time and place in the cell).

A

false

69
Q

In eukaryotes pre-mRNA is much longer than the mRNA that eventually be translated. This can be explained by which of the following?

A

Introns have not yet been removed from the transcript

70
Q

Gene expression regulation can occur at which steps:

A

translation and transcription

71
Q

Genes that are expressed at a constant level all the time are said to be:

A

constitutive

72
Q

Operons are found in the cells of which of the following types of organisms?

A

prokaryotes

73
Q

When a repressor binds to the operator site on the DNA it normally _________.

A

inhibits the initiation of transcription

74
Q

__________ activate repressor proteins, thereby decreasing the synthesis of certain enzymes.

A

Corepressors

75
Q

__________ alter repressor proteins thereby increasing the rate of transcription initiation.

A

Inducers

76
Q

When the catabolite activator protein (CAP) binds to its binding site in DNA, it _________.

A

promotes the RNA polymerase binding to the promoter

77
Q

E.coli LacZ gene, which codes for the enzyme beta-galactosidase, is in the Lac operon. E. coli cells exposed to which of the following conditions would produce the highest amount of beta-galactosidase?

A

lactose is present, and glucose is absent

78
Q

An example of repressible operon is:

A

Trp operon

79
Q

Which is false regarding the two-component regulatory system in bacteria?

A

The sensor kinase is phosphorylated by the response regulator when the extracellular environment changes

80
Q

T/F Mutation is defined as a change in cell’s phenotype.

A

false

81
Q

A __________ mutation does not alter the amino acid sequence of the resulting protein.

A

silent

82
Q

A __________ mutation is one that causes premature termination of the synthesis of the protein product.

A

nonsense

83
Q

Conjugation is the transfer of DNA from a donor to a recipient cell:

A

by cell-to-cell contact via sex pili

84
Q

T/F Transformation is the transfer of DNA to donor cells by bacteriophage.

A

false

85
Q

Transduction requires a(n) ________ to move DNA from one bacterial cell to another.

A

bacteriophage

86
Q

T/F Transduction is an example of vertical DNA transfer.

A

False

87
Q

T/F In recombinant DNA technology, a vector is a self-replicating DNA, such as a plasmid.

A

true

88
Q

T/F Restriction enzymes catalyze the hydrolysis of phosphodiester bonds of a DNA at a specific site.

A

true

89
Q

In cloning, the enzyme that joins the DNA fragments together is:

A

ligase

90
Q

You have a small gene that you wish to amplify by PCR. After 4 replication cycles, how many double-stranded DNA molecules do you have if you started with a single molecule?

A

16

91
Q

What happens during the Denaturing step of PCR?

A

The double-stranded DNA is separated into two single strands of DNA

92
Q

If the primer sequence for PCR is 5’-TCG-3’, what sequence of DNA will it anneal to?

A

3’-AGC-5’

BIO SCI 101 (3 decks)

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