Microbiology Investigation: Food and Water Contamination
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Questions and Answers

If food/water samples are stored at improper temperatures, then the number of microbial ______ will be higher.

colonies

The ______ variable is the storage temperature of food/water samples.

independent

The ______ variable is the number of microbial colonies grown on the agar plate.

dependent

The ______ variables are the type of food/water sample and incubation time.

<p>controlled</p> Signup and view all the answers

You would expect the health of the birds in cage a (with ______) to deteriorate compared to those in cage B.

<p>disinfectant</p> Signup and view all the answers

Aseptic techniques prevent ______ in microbiology.

<p>contamination</p> Signup and view all the answers

Symptoms of the disease might include ______ issues and behavioral changes/distress.

<p>respiratory</p> Signup and view all the answers

Validity ensures that the method accurately measures what's ______ to.

<p>intended</p> Signup and view all the answers

To test if the sun is causing the disease, you would place one group of birds in a ______ position.

<p>sunnier</p> Signup and view all the answers

Agar acts as a ______ rich medium that supports microbial growth.

<p>nutrient</p> Signup and view all the answers

The term ______ refers to the physical appearance of an infectious disease.

<p>symptoms</p> Signup and view all the answers

Aerobic bacteria require ______ to thrive, whereas anaerobic bacteria can grow without it.

<p>oxygen</p> Signup and view all the answers

Proper food handling and storage are justified as they significantly reduce microbial growth, ensuring ______ safety.

<p>food</p> Signup and view all the answers

The researcher who infected himself with the bacteria raises ______ concerns, including the risk of severe health consequences.

<p>ethical</p> Signup and view all the answers

An investigation was carried out after sewage was dumped into the ______.

<p>river</p> Signup and view all the answers

The graph shows what happened to a fish in the ______ after the dumping of raw sewage at point A.

<p>river</p> Signup and view all the answers

As the ______ in the water increased, the dissolved oxygen dipped.

<p>bacteria levels</p> Signup and view all the answers

The ______ in the swan neck flask did not decay because the bacteria cannot go in.

<p>broth</p> Signup and view all the answers

The curved neck of the swan neck flask trapped ______ and microorganisms, preventing them from reaching the broth.

<p>dust</p> Signup and view all the answers

Koch's postulates are used to identify a microorganism as the ______ agent of a specific disease.

<p>causative</p> Signup and view all the answers

Suspected pathogens must be present in all cases of the ______ and absent from healthy individuals.

<p>disease</p> Signup and view all the answers

The long curved neck of the swan neck flask allowed ______ to enter, but trapped dust and microorganisms.

<p>air</p> Signup and view all the answers

If the swan neck was broken off the flask, ______ microorganisms would enter directly into the broth.

<p>airborne</p> Signup and view all the answers

Bacteria consume ______ during metabolic activities, reducing the amount of oxygen available in water.

<p>oxygen</p> Signup and view all the answers

To prevent contamination, the neck of the flask is bent into an ______ shape.

<p>S</p> Signup and view all the answers

Data that involves numbers, such as colony counts, is considered ______ data.

<p>quantitative</p> Signup and view all the answers

The absence of microbial growth in the controlled environment reaffirms Pasteur's findings that microbes come from ______ contamination.

<p>external</p> Signup and view all the answers

A hazard of the swan neck flask experiment is the risk of ______ from the Bunsen burner.

<p>skin burns</p> Signup and view all the answers

One of the possible causes of disease in the birds is the use of a new ______.

<p>disinfectant</p> Signup and view all the answers

To determine the cause of the disease, the bird breeder set up two groups of birds, including a ______ group without disinfectant.

<p>control</p> Signup and view all the answers

The bird breeder ensured that everything else was identical in each cage, including the number of ______.

<p>birds</p> Signup and view all the answers

The bird breeder took ______ precautions, such as wearing gloves and glasses, to minimize the risk of hazards.

<p>safety</p> Signup and view all the answers

Louis Pasteur was appointed to the Uni of ______ in 1854.

<p>Lillie</p> Signup and view all the answers

Dr. John Snow conducted pioneering investigations on ______ epidemics in England and particularly in London in 1854.

<p>cholera</p> Signup and view all the answers

Rabies is a disease caused by a ______ that affects mammals.

<p>virus</p> Signup and view all the answers

Louis Pasteur was not able to observe the rabies ______ because viruses are too small to be seen with a light microscope.

<p>virus</p> Signup and view all the answers

Dr. John Stone was gathering evidence to support the hypothesis: A specific water pump was contaminated with ______, responsible for causing the cholera outbreaks.

<p>cholera</p> Signup and view all the answers

Louis Pasteur studied samples of ______ under a microscope.

<p>wine</p> Signup and view all the answers

Louis Pasteur found that good and bad fermentation is due to the activities of different ______.

<p>microorganisms</p> Signup and view all the answers

In 1880 Louis Pasteur investigated dogs that were suffering from ______ in order to find the cause.

<p>rabies</p> Signup and view all the answers

Study Notes

Hypothesis and Variables

  • A hypothesis is a statement predicting the outcome of an investigation, e.g., "If food/water samples are stored at improper temperatures, then the number of microbial colonies will be higher."
  • Independent variable: the storage temperature of food/water samples
  • Dependent variable: the number of microbial colonies grown on the agar plate
  • Controlled variables: type of food/water sample and incubation time

Controlled Variables

  • Controlled variables are kept constant to ensure that any differences in microbial growth are due solely to the independent variable
  • Example: incubation times are standardized across all experiments to ensure consistency

Aseptic Technique

  • Aseptic techniques prevent contamination, ensuring only targeted microbes are studied
  • Techniques include using sterilized instruments and maintaining a clean workspace

Validity, Reliability, and Accuracy

  • Validity: ensures the method accurately measures what's intended to be measured
  • Reliability: ensures consistency across trials and tests
  • Accuracy: how close results are to the true value

Agar and Microbial Growth

  • Agar acts as a nutrient-rich medium that supports microbial growth, allowing for the observation and quantification of colonies
  • Proper food handling and storage significantly reduce microbial growth, ensuring food safety and preventing foodborne illnesses

Swan Neck Flask Experiment

  • Sterilize broth in a flask, then bend the neck into an 'S' shape
  • Heat to kill existing microbes, then incubate
  • The bend traps dust and microbes, preventing contamination

Quantitative and Qualitative Data

  • Quantitative data involves numbers, e.g., colony counts
  • Qualitative data describes characteristics without numbers

Risk Assessment and Hazards

  • Hazards include skin burns from Bunsen burners
  • Safety precautions include wearing PPE (glasses, gloves, apron) and using burners safely

Disease Investigation

  • The student's investigation reaffirms Pasteur's findings that microbes come from external contamination, not spontaneous generation
  • Potential causes of disease in birds: new disinfectant, increased sunlight, stress from environmental changes

Symptoms and Incubation Period

  • Symptoms: physical appearance of an infectious disease, e.g., respiratory issues, behavioral changes/distress
  • Incubation period: the time between exposure and the appearance of symptoms

Louis Pasteur's Experiment

  • If the swan neck was broken off the flask, airborne microorganisms could enter the broth, leading to microbial growth
  • The curved neck trapped dust and microorganisms, preventing them from reaching the broth, yet allowing air to enter
  • Koch's postulates are used to identify a microorganism as the causative agent of a specific disease

Rabies and Viruses

  • Rabies is caused by a viral agent that infects the nervous system of mammals, not by bacteria
  • Louis Pasteur was not able to observe the rabies virus because viruses are too small to be seen with a light microscope

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Description

Understand the relationship between storage temperature and microbial growth in food and water samples. Explore the variables involved in this investigation and their effects on contamination.

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