MICROBIOLOGY 2117 UPDATED EXAMS TEST PAPER
QUESTIONS AND ANSWERS SURE A+
✔✔Why do you have to "heat fix" bacteria? - ✔✔it attaches the microorganisms to the
surface of the slide
✔✔What type of charge does a simple stain have? Why? - ✔✔positive- because they
are cations.
✔✔Name two simple stains: - ✔✔1. Crystalline Violet 2. Methylene blue
✔✔What is a negative stain? Is it the same as a gram negative stain? - ✔✔A negative
stain is used for bacteria with capsules which are colorless and invisible if unstained.
No- it is NOT the same as gram negative.
✔✔Explain what happens when you use a differential stain: - ✔✔Differential stain uses
more than one stain to differentiate between bacteria or structures.
✔✔Examples of differential stains: - ✔✔Ziehl Neelsen stain, Gram stain, endospore
stain
✔✔What is the Ziehl Neelsen stain? - ✔✔a procedure that results in pink acid fast cells
which can be differentiated from blue non acid fast cells
,✔✔Explain the four steps of the gram stain: - ✔✔1. primary stain: crystalline violet
stains all bacteria purple 2. mordant: grams iodine sets the stain 3. decolorizer: ethanol
washes out the stain from gram negative bacteria only 4. counterstain: safranin stains
gram negative bacteria pink
✔✔What is the basis for the difference in staining? - ✔✔makes microorganisms easier
to identify
✔✔Name the different shapes that bacteria can have: - ✔✔1. coccus = round 2. bacillus
= rod shaped 3. spirilla = wavy 4. spirochete = corkscrew 5. vibrio = curved rod
✔✔What is a spirochete? - ✔✔group of helical gram negative bacteria with axial
filaments that cause an organism to corkscrew, thus burrowing in a hosts tissue.
✔✔Does water contain polar or non polar bonds? - ✔✔polar
✔✔Which compounds dissolve in water? - ✔✔Na+, sugar, alcohol
✔✔How does water help to regulate temperature? - ✔✔Its high specific heat allows
water to act as a heat sink. Water will retain its temperature after absorbing large
amounts of heat, and retain its temperature after losing equally large amounts of heat
✔✔What happens in hydrolysis reactions? - ✔✔water breaks bonds
✔✔What happens in dehydration reactions? - ✔✔water is removed to build bonds
between molecules
✔✔Define acidity: - ✔✔number of H+ in a solution
✔✔What does it mean if the pH is 6.0? - ✔✔the solution is slightly acidic
✔✔What is the difference between a pH of 5.0 and 6.0? - ✔✔5.0 is 100 times more
acidic than 6.0
✔✔Which pH levels are basic, neutral and acidic? - ✔✔Basic = 7.1-14 ; Neutral = 7 ;
Acidic = 6.9-0
✔✔What is a buffer? What two components must it have? - ✔✔a buffer is a solution that
is resistant to large changes in pH. Must have carbonic acid and bicarbonate.
✔✔Name four major groups of organic compounds: - ✔✔1. carbohydrates 2. lipids 3.
protein 4. nucleic acids
, ✔✔What does "organic" mean? - ✔✔organic means that the substance contains carbon
atoms. Scientists believe that organic compounds can only be formed by life processes.
✔✔Name the major functions of carbohydrates: - ✔✔short term energy storage; also
structural components of cells
✔✔Which elements to carbs contain? - ✔✔C, H, O
✔✔Do carbs dissolve in water? - ✔✔if they are in simple form, yes. If not, they must be
broken down by an enzyme before they can dissolve in water.
✔✔What is a simple sugar? - ✔✔basic subunit of a carbohydrate
✔✔list three simple sugars (monosaccharides) : - ✔✔1. glucose 2. fructose 3. galactose
✔✔What is a disaccharide? List three: - ✔✔A disaccharide is a double sugar consisting
of two monosaccharides joined by dehydration synthesis. Three disaccharides include:
1. sucrose 2. maltose 3. lactose
✔✔What is a polysaccharide? List three: - ✔✔A polysaccharide is a complex molecule
of three or more monosaccharides joined by dehydration synthesis. Three
polysacchardies include: 1. glycogen 2. cellulose 3. starch
✔✔How are polysaccharides broken down? - ✔✔by hydrolysis
✔✔Name the major functions of fat: - ✔✔long term energy storage, transportation of
vitamins K, A, D, E
✔✔Which elements do most fats contain? - ✔✔C, H
✔✔Do fats dissolve in water? - ✔✔NO- they are non polar
✔✔What are the two parts of a triglyceride? - ✔✔1. glycerol backbone 2. three fatty acid
tails
✔✔Are the fatty acid chains polar or non polar? - ✔✔nonpolar
✔✔What is the difference between unsaturated fat and saturated fat? - ✔✔unsaturated
fat has double bonds/ saturated fat has NO double bonds
✔✔How is a phospholipid different from a triglyceride? - ✔✔Phospholipids have a
phosphate group and two fatty acid chains; Triglycerides have a roll of glycerol and
three fatty acid chains
QUESTIONS AND ANSWERS SURE A+
✔✔Why do you have to "heat fix" bacteria? - ✔✔it attaches the microorganisms to the
surface of the slide
✔✔What type of charge does a simple stain have? Why? - ✔✔positive- because they
are cations.
✔✔Name two simple stains: - ✔✔1. Crystalline Violet 2. Methylene blue
✔✔What is a negative stain? Is it the same as a gram negative stain? - ✔✔A negative
stain is used for bacteria with capsules which are colorless and invisible if unstained.
No- it is NOT the same as gram negative.
✔✔Explain what happens when you use a differential stain: - ✔✔Differential stain uses
more than one stain to differentiate between bacteria or structures.
✔✔Examples of differential stains: - ✔✔Ziehl Neelsen stain, Gram stain, endospore
stain
✔✔What is the Ziehl Neelsen stain? - ✔✔a procedure that results in pink acid fast cells
which can be differentiated from blue non acid fast cells
,✔✔Explain the four steps of the gram stain: - ✔✔1. primary stain: crystalline violet
stains all bacteria purple 2. mordant: grams iodine sets the stain 3. decolorizer: ethanol
washes out the stain from gram negative bacteria only 4. counterstain: safranin stains
gram negative bacteria pink
✔✔What is the basis for the difference in staining? - ✔✔makes microorganisms easier
to identify
✔✔Name the different shapes that bacteria can have: - ✔✔1. coccus = round 2. bacillus
= rod shaped 3. spirilla = wavy 4. spirochete = corkscrew 5. vibrio = curved rod
✔✔What is a spirochete? - ✔✔group of helical gram negative bacteria with axial
filaments that cause an organism to corkscrew, thus burrowing in a hosts tissue.
✔✔Does water contain polar or non polar bonds? - ✔✔polar
✔✔Which compounds dissolve in water? - ✔✔Na+, sugar, alcohol
✔✔How does water help to regulate temperature? - ✔✔Its high specific heat allows
water to act as a heat sink. Water will retain its temperature after absorbing large
amounts of heat, and retain its temperature after losing equally large amounts of heat
✔✔What happens in hydrolysis reactions? - ✔✔water breaks bonds
✔✔What happens in dehydration reactions? - ✔✔water is removed to build bonds
between molecules
✔✔Define acidity: - ✔✔number of H+ in a solution
✔✔What does it mean if the pH is 6.0? - ✔✔the solution is slightly acidic
✔✔What is the difference between a pH of 5.0 and 6.0? - ✔✔5.0 is 100 times more
acidic than 6.0
✔✔Which pH levels are basic, neutral and acidic? - ✔✔Basic = 7.1-14 ; Neutral = 7 ;
Acidic = 6.9-0
✔✔What is a buffer? What two components must it have? - ✔✔a buffer is a solution that
is resistant to large changes in pH. Must have carbonic acid and bicarbonate.
✔✔Name four major groups of organic compounds: - ✔✔1. carbohydrates 2. lipids 3.
protein 4. nucleic acids
, ✔✔What does "organic" mean? - ✔✔organic means that the substance contains carbon
atoms. Scientists believe that organic compounds can only be formed by life processes.
✔✔Name the major functions of carbohydrates: - ✔✔short term energy storage; also
structural components of cells
✔✔Which elements to carbs contain? - ✔✔C, H, O
✔✔Do carbs dissolve in water? - ✔✔if they are in simple form, yes. If not, they must be
broken down by an enzyme before they can dissolve in water.
✔✔What is a simple sugar? - ✔✔basic subunit of a carbohydrate
✔✔list three simple sugars (monosaccharides) : - ✔✔1. glucose 2. fructose 3. galactose
✔✔What is a disaccharide? List three: - ✔✔A disaccharide is a double sugar consisting
of two monosaccharides joined by dehydration synthesis. Three disaccharides include:
1. sucrose 2. maltose 3. lactose
✔✔What is a polysaccharide? List three: - ✔✔A polysaccharide is a complex molecule
of three or more monosaccharides joined by dehydration synthesis. Three
polysacchardies include: 1. glycogen 2. cellulose 3. starch
✔✔How are polysaccharides broken down? - ✔✔by hydrolysis
✔✔Name the major functions of fat: - ✔✔long term energy storage, transportation of
vitamins K, A, D, E
✔✔Which elements do most fats contain? - ✔✔C, H
✔✔Do fats dissolve in water? - ✔✔NO- they are non polar
✔✔What are the two parts of a triglyceride? - ✔✔1. glycerol backbone 2. three fatty acid
tails
✔✔Are the fatty acid chains polar or non polar? - ✔✔nonpolar
✔✔What is the difference between unsaturated fat and saturated fat? - ✔✔unsaturated
fat has double bonds/ saturated fat has NO double bonds
✔✔How is a phospholipid different from a triglyceride? - ✔✔Phospholipids have a
phosphate group and two fatty acid chains; Triglycerides have a roll of glycerol and
three fatty acid chains
