Growth Phases of Organisms
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Questions and Answers

What is the purpose of caesin hydrolysate?

Caesin hydrolysate is useful in identifying organisms that can cause hemolysis, or breakdown of red blood cells.

What is the function of blood agar?

Blood agar is a medium that encourages growth of some organisms but suppresses the growth of others.

What is a selective medium?

A selective medium is a medium that has a constituent that causes an observable change in the medium when a particular biochemical reaction occurs.

What is a differential medium?

<p>A differential medium is a medium that has a constituent that causes an observable change in the medium when a particular biochemical reaction occurs.</p> Signup and view all the answers

What are SPS and MacConkey agar?

<p>SPS and MacConkey agar are selective and differential mediums.</p> Signup and view all the answers

What is lactose?

<p>Lactose is a sugar that organisms in the human intestines ferment, whereas most pathogens do not.</p> Signup and view all the answers

What is the pour plate method?

<p>The pour plate method is a technique where a diluted culture is added to a melted nutrient agar and poured into an empty dish, allowing bacteria to grow on top of the agar.</p> Signup and view all the answers

What is the spread plate method?

<p>The spread plate method is a technique where a diluted sample is placed on the center of a solid cooled agar medium and spread evenly, allowing colonies to develop on the agar surface.</p> Signup and view all the answers

What is a colony forming unit (CFU)?

<p>A colony forming unit (CFU) is a single living bacterium that is deposited on an agar plate and divides to form a colony.</p> Signup and view all the answers

What is the most probable number (MPN) method?

<p>The most probable number (MPN) method is a method of estimating the size of small bacterial populations when samples contain too few organisms to give reliable measures of population size by the standard plate count method.</p> Signup and view all the answers

What is the purpose of the lag phase?

<p>During the lag phase, organisms increase in size, synthesize enzymes, and incorporate various molecules from the medium.</p> Signup and view all the answers

What happens during the log phase?

<p>Population growth occurs at an exponential rate during the log phase.</p> Signup and view all the answers

What is the stationary phase characterized by?

<p>During the stationary phase, conditions in the medium become less supportive of cell division, cells lose their ability to divide, and cells die.</p> Signup and view all the answers

What happens during the decline phase?

<p>During the decline phase, cell division decreases to the point that new cells are produced at the same rate as old cells die, so the number of cells remains constant.</p> Signup and view all the answers

What is the generation time?

<p>The generation time is the time it takes for organisms to divide at their most rapid rate.</p> Signup and view all the answers

What is synchronous growth?

<p>Synchronous growth refers to cells dividing sometime during the generation time with a smooth line graph rather than a stair step pattern.</p> Signup and view all the answers

What is nonsynchronous growth?

<p>Nonsynchronous growth refers to cells dividing together exactly and increasing in a stair step pattern.</p> Signup and view all the answers

What is a colony?

<p>A colony is a group of descendants of the original cell.</p> Signup and view all the answers

What is the streak plate method?

<p>The streak plate method is a method that uses agar plates and involves picking up bacteria on a sterile wire loop and depositing streaks of bacteria along the surface.</p> Signup and view all the answers

What is the difference between natural and synthetic media?

<p>Natural media are materials found in nature, while synthetic media are materials from the laboratory.</p> Signup and view all the answers

During which phase do organisms increase in size and synthesize enzymes?

<p>Lag phase (B)</p> Signup and view all the answers

During which phase does population growth occur at an exponential rate?

<p>Log phase (B)</p> Signup and view all the answers

During which phase does cell division decrease and the number of cells remain constant?

<p>Stationary phase (A)</p> Signup and view all the answers

During which phase do cells lose their ability to divide and die?

<p>Decline phase (D)</p> Signup and view all the answers

What is the term for organisms dividing at their most rapid rate?

<p>Generation time (B)</p> Signup and view all the answers

What is the term for cells dividing together exactly and increasing in a stair step pattern?

<p>Synchronous growth (C)</p> Signup and view all the answers

What is the term for cells dividing sometime during the generation time with a smooth line graph?

<p>Nonsynchronous growth (C)</p> Signup and view all the answers

What is the term for growth in colonies?

<p>Colony (B)</p> Signup and view all the answers

What is the term for chemically non-defined medium that varies slightly in chemical composition?

<p>Complex media (B)</p> Signup and view all the answers

What is the term for a media that contains known specific kinds and amount of chemical substances?

<p>Defined synthetic media (B)</p> Signup and view all the answers

Which type of medium encourages the growth of some organisms but suppresses the growth of others?

<p>Blood agar (A)</p> Signup and view all the answers

What is the purpose of caesin hydrolysate?

<p>To identify organisms that can cause hemolysis (C)</p> Signup and view all the answers

What is the most probable number (MPN) method used for?

<p>Estimating the size of small bacterial populations (A)</p> Signup and view all the answers

What is the purpose of SPS and MacConkey agar?

<p>To ferment by organisms in the human intestines (A)</p> Signup and view all the answers

What is lactose primarily fermented by?

<p>Organisms in the human intestines (C)</p> Signup and view all the answers

What is the pour plate method used for?

<p>Spreading a diluted sample evenly on a solid cooled agar medium (C)</p> Signup and view all the answers

What is the spread plate method used for?

<p>Measuring bacterial growth indirectly (A)</p> Signup and view all the answers

What is a colony forming unit (CFU)?

<p>A colony known as a single living bacterium deposited on an agar plate (A)</p> Signup and view all the answers

What is the purpose of the dye reduction test?

<p>To measure the direct or indirect uptake of oxygen (C)</p> Signup and view all the answers

What is methylene blue used for?

<p>To turn blue in the presence of oxygen and colorless in its absence (D)</p> Signup and view all the answers

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