18 Questions
What are the key nutrients required for bacteria to multiply quickly?
Carbohydrates, proteins, minerals, and vitamins
Why is the maximum allowed temperature for bacterial growth in a school lab typically set at 25°C?
Above this temperature, more harmful pathogens are likely to grow.
In what two forms can bacteria be grown for study?
Nutrient broth solution or as colonies on an agar gel plate
Why is it vital to grow uncontaminated cultures of microorganisms in the lab?
Competing species can affect the growth of cultures and the validity of any study performed.
What is the purpose of aseptic techniques in microbiology?
To ensure uncontaminated culture preparation and accurate experimental results.
How does temperature affect the growth rate of bacteria?
Warmer temperatures promote faster growth.
What is the aim of investigating bacterial growth using agar plates and measuring zones of inhibition?
To investigate the effect of antiseptics or antibiotics on bacterial growth.
What technique is used to place filter paper discs soaked in antiseptics/antibiotics onto agar plates containing bacteria?
Aseptic technique.
Why is preventing contamination important in microbiology investigations?
To ensure that you are only investigating the effect of antiseptics or antibiotics on the desired bacterial species.
Which bacterial cultures are commonly used in practicals involving investigating bacterial growth?
Escherichia coli (E. coli) or Micrococcus luteus.
What is the purpose of calculating the area of each zone of inhibition?
To quantitatively compare the effects of different antiseptics/antibiotics.
What is the significance of using uncontaminated agar plates in the investigation of bacterial growth?
To ensure accurate results by eliminating interference from external microorganisms.
Why is it important to only lift the lid of the petri dish a little when working with bacterial cultures?
To reduce the risk of contamination by other microorganisms.
Why is calculating the area of an inhibition zone a more accurate way of comparing the effect of different substances on bacterial growth?
It provides a quantitative measurement compared to judging by sight.
What equation is used to calculate the area of an inhibition zone?
Area = πr^2
Why is it more accurate to measure the diameter of an inhibition zone rather than the radius?
Measuring the diameter directly is more precise for calculating the area.
What is the purpose of taking at least two measurements of the diameter of an inhibition zone?
To find the mean diameter for a more accurate area calculation.
Why is it necessary to half the diameter measurement before using the area equation to calculate the inhibition zone area?
Because the area formula uses the radius, not the diameter.
Test your knowledge on the ideal conditions required for the growth of bacterial cultures in a laboratory setting. Explore how nutrients and temperature affect the multiplication of bacteria and learn about the risks associated with higher temperatures.
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