·       In one experiment Lederberg used Gal⁺ and Gal^– strains of E. coli. One half of a plate that contained medium with galactose as the only carbon source was inoculated with phages that came from lysed cells of the Gal⁺ strain. The other half of the plate was left uninoculated. A Gal^- strain was then placed on the entire plate. Numerous colonies appeared on the half of the plate inoculated with the phage, whereas only a few appeared on the half that was not inoculated with phage. Explain what happened using appropriate terminology.

Marine Biology Question- What is an "anthropogenic stressor"?

Marine Biology Question- what are "Nonconsumptive predator effects (or, more generally, non-consumptive effect, NCE)"?

84. ________ was the first to describe microorganisms, while ________ was the first person to see bacteria.

a. Antoni van Leeuwenhoek / Robert Hook

b. Antoni van Leeuwenhoek / Robert Koch

c. Robert Hooke / Antoni van Leeuwenhoek

d. Robert Koch / Antoni van Leeuwenhoek

85. Archaea and Bacteria are unified as prokaryotes in lacking ________ which Eukarya contain, such as golgi.

a. membranes

b. nuclei

c. membrane-enclosed organelles

d. nuclei and membrane-enclosed organelles

86. A bacterial species has a generation time of 20 minutes and is growing exponentially. If there are 10 cells initially how many cells are there after 80 minutes?

a. 30

b. 80

c. 160

d. 200

e. none of the above

87. The growth of almost all bacteria in the environment

a. is limited by cool temperatures

b. is limited by high pH

c. is limited by the availability of one or more nutrients

d. is unlimited because bacteria are metabolically versatile

88. According to Koch’s postulates a microorganism thought to cause a disease in one species of animal.

a. must be seen in samples of blood using a microscope

b. must be isolated in pure culture and then used to cause the same disease in healthy animals

c. must never be found in healthy individuals

d. answers (b) and (c) are correct

89. Antoni van Leeuwenhoek developed and used

a. the first compound microscope

b. the first vaccine to prevent an infectious disease

c. a microscope with a single lens

d. pasteurization to prevent the spoilage of food

90. Gram positive bacteria

a. have a thick cell wall, which retains the crystal violet dye when cells are Gram stained

b. contain teichoic acid in their cell walls

c. appear purple when Gram stained

d. all the above e. none of the above

91. The cell envelope of Gram negative bacteria

a. includes a thick cell wall

b. includes both an inner and outer membrane

c. includes a peptidoglycan layer

d. always includes a capsule made of polysaccharides

e. answers (b) and (c) are correct

92. The cell membrane of bacteria

a. is semi-permeable

b. is usually a lipid bilayer

c. prevents cell lysis due to high intracellular osmotic pressure

d. answers (a) and (b) are correct

e. answers (a) and (c) are correct

93. Regarding early life on Earth,

a. microbial life existed for hundreds of millions of years before plant and animal life

b. microbial life existed long before animals but has been around for about the same amount of time as plants

c. microbial life, plant life, and animal life all appeared at about the same time

d. it is impossible to determine which type of life first appeared.

94. The structure that confers structural strength on bacterial cells is known as the

a. cytoplasmic membrane

b. cell wall

c. ribosome

d. cytoplasm

95. Archaea and Bacteria are unified as prokaryotes in lacking ______________

a. membranes

b. nuclei

c. membrane-enclosed organelles

d. nuclei and membrane-enclosed organelles

96. When a bacterial culture contains only one type of organism, it is called a ______________.

a. mixed culture

b. liquid culture

c. environmental culture

d. pure culture

97. Prokaryotes and eukaryotes

a. have the same kinds of metabolic pathways, but little else in common

b. have nothing in common

c. have many things in common because they share a common ancestor

d. are identical to each other

98. Which of the following statements is true?

a. peptidoglycan is comprised of cross-linked fatty acids

b. the cell walls of most bacteria are composed of peptidoglycan

c. Gram-negative bacteria have a relatively thick layer of peptidoglycan

d. peptidoglycan is found mainly in the cell walls of fungi, algae and plants

e. answers (a) and (b) are both correct

99. The cell membrane of bacteria

a. is semi-permeable.

b. is usually a lipid bilayer

c. prevents cell lysis due to high intracellular osmotic pressure

d. answers (a) and (b) are correct

e. answers (a) and (c) are correct

100. A bacterial species has a generation time of 15 minutes and is growing exponentially. If there are 2 cells initially how many cells are there after 90 minutes?

a. 256

b. 128

c. 64

d. 32

e. none of the above

101. Most bacterial cells reproduce by

a. the budding of daughter cells from a mother cell

b. forming spores that later germinate

c. binary fission

d. production of gametes and sexual reproduction  

102. Which of these are routinely used to obtain a pure culture of bacteria?

a. swan necked flasks

b. agar streak plates

c. dilution plates

d. microscopes

103. The cells of all species of Bacteria and Archaea are very small, and:

a. must be stained before they can be seen using light microscopy

b. can only be seen using electron microscopy

c. can only be seen if they are first Gram stained

d. none of the above

104. Prokaryotes evolved early on in the history of the Earth:

a. so their physiology has little in common with Eukaryotes

b. so many aspects of their physiology also occur in Eukaryotes, which evolved much later in in the history of the Earth

c. and Eukaryotes evolved independently at a much later time in the history of the Earth

d. at about the same time that Eukaryotes first appeared on Earth

Does current flow from positive to negative, or negative to positive? Which way does current flow across the membrane during the rising phase of the action potential? During the falling phase?

The countercurrent arrangement of the two limbs of the loop of Henle becomes a multiplier of electrolyte concentration due to which other characteristic?

A. water permeability of the descending limb

B. water impermeability of the ascending limb

C. active transport of electrolytes out of the ascending limb

D. thickness of the ascending limb

Question Aerosols include all the following EXCEPT: a. smoke b. mists c. dusts d. vapor

Digest the following proteins with the proteases listed and comment whether the original sequence can be inferred based on the proteolytic patterns a. MARRIEDEARLYANDPAIDDEARLY: Separately with trypsin and chymotrypsin b. WINETHISAD: Separately with elastase and chymotrypsin. c. MYSTERYPI: With both trypsin and elastase together

Consider an LB broth flask into which two E. coli strains are inoculated. Strain "A" is wild-type, with g = 22 min at 37oC, and 45 min at 27oC. Strain "B" has a temperature-sensitive mutation, such that g = 52 min at 37oC, but at 27oC g = 44 min.We inoculate equal amounts of cells (1 ml of each starter culture whose population is 1 x 106 cfu/ml) into each of two separate 1 liter volumes of LB broth at time = 0. One of the flasks is incubated at 37oC, one at 27oC.Assuming constant exponential growth (i.e. no lag phase, and no exhaustion of nutrients), answer each of these questions:

1) After 6 hours of growth, what is the final concentration of each strain in each flask?

2) What fraction of the total population is Strain A and Strain B in each flask?

How can a protein act as a signal integrating sensor?

1. Explain how lipids are digested and absorbed.

2. Differentiate among saturated, monounsaturated, and polyunsaturated fatty acids in terms of structure and food sources.

3. List four classes of lipids and the role of each in nutritional health. Distinguish between fatty acids and triglycerides.

Which phase do the chromosomes duplicate?

Which phase does the cell spend most of its lifetime and approximately how long?

What is the mitotic spindle?

What is a centriole and what is its function?

Centrioles are located inside what?
Where does the mitotic spindle grow out of?

Duplicate chromosomes and duplicated centrosomes would mark the end of what?

Do chromosomes form before or after the cell enters mitosis?

How is the chromosome structured?

Sister chromatids form when the chromosome ____

Sister chromatids contain what when compared to each other?

The lifetime of a cell or time between cell divisions refers to what?

What is interphase?

What is M phase?

Suppose we know p and q for a given 2-allele population. Which term in the Hardy-Weinberg Equilibrium provides the frequency of heterozygotes in that population?