BCH 5413 BIOCHEMISTRY TEST PAPER
QUESTIONS AND SOLUTIONS VERIFIED
ANSWERS
●● Why Pure Cultures Are Important:
Answer: Used to study bacterial metabolism and morphology without
contamination from other microbes.
●● Growth Medium:
Answer: Nutrient material used to grow bacteria; must be sterilized
before inoculation.
●● Aseptic Technique:
Answer: Procedures used to prevent contamination of people, materials,
the environment, and cultures.
●● Streak Plating:
Answer: Method used to isolate bacteria by dragging cells across an agar
plate to dilute them.
●● Well-Isolated Colonies:
Answer: Colonies separated enough to likely contain cells from only one
bacterium type.
,●● Mixed Culture:
Answer: Culture containing more than one species of microorganism.
●● Colony Morphology:
Answer: The visible characteristics of bacterial colonies such as shape,
size, color, and texture.
●● Spread Plating:
Answer: Method where diluted bacteria are spread evenly across agar to
isolate or count cells.
●● Serial Dilution:
Answer: Stepwise dilution process used to reduce bacterial
concentration gradually.
●● Confluent Growth (Lawn):
Answer: Continuous bacterial growth covering the entire agar surface.
●● Direct Microscopic Count:
Answer: Counting cells directly under a microscope using a counting
chamber.
, ●● Advantage of Direct Microscopic Counts:
Answer: Rapid way to estimate cell numbers.
●● Disadvantage of Direct Microscopic Counts:
Answer: Cannot distinguish living cells from dead cells.
●● Counting by Spread Plating:
Answer: Method of estimating viable bacteria by counting colonies
formed on agar plates.
●● Valid Colony Count Range:
Answer: Plates with 30-300 colonies are considered accurate for
counting.
●● Concentration:
Answer: Amount of particles or cells per unit volume.
●● Concentration Formula:
Answer: C = P / V (concentration = particles ÷ volume).
●● Dilution:
Answer: Reduction in concentration by adding diluent.
QUESTIONS AND SOLUTIONS VERIFIED
ANSWERS
●● Why Pure Cultures Are Important:
Answer: Used to study bacterial metabolism and morphology without
contamination from other microbes.
●● Growth Medium:
Answer: Nutrient material used to grow bacteria; must be sterilized
before inoculation.
●● Aseptic Technique:
Answer: Procedures used to prevent contamination of people, materials,
the environment, and cultures.
●● Streak Plating:
Answer: Method used to isolate bacteria by dragging cells across an agar
plate to dilute them.
●● Well-Isolated Colonies:
Answer: Colonies separated enough to likely contain cells from only one
bacterium type.
,●● Mixed Culture:
Answer: Culture containing more than one species of microorganism.
●● Colony Morphology:
Answer: The visible characteristics of bacterial colonies such as shape,
size, color, and texture.
●● Spread Plating:
Answer: Method where diluted bacteria are spread evenly across agar to
isolate or count cells.
●● Serial Dilution:
Answer: Stepwise dilution process used to reduce bacterial
concentration gradually.
●● Confluent Growth (Lawn):
Answer: Continuous bacterial growth covering the entire agar surface.
●● Direct Microscopic Count:
Answer: Counting cells directly under a microscope using a counting
chamber.
, ●● Advantage of Direct Microscopic Counts:
Answer: Rapid way to estimate cell numbers.
●● Disadvantage of Direct Microscopic Counts:
Answer: Cannot distinguish living cells from dead cells.
●● Counting by Spread Plating:
Answer: Method of estimating viable bacteria by counting colonies
formed on agar plates.
●● Valid Colony Count Range:
Answer: Plates with 30-300 colonies are considered accurate for
counting.
●● Concentration:
Answer: Amount of particles or cells per unit volume.
●● Concentration Formula:
Answer: C = P / V (concentration = particles ÷ volume).
●● Dilution:
Answer: Reduction in concentration by adding diluent.
