Q:

What do biochemical tests determine?

A:

Quick Answer

Biochemical tests are used to detect the presence or absence of gram-negative or gram-positive bacteria. These tests are commonly used in the fields of science and medicine, particularly biology. Biochemical tests are performed using a variety of methods and experimental techniques; the method of testing varies depending on whether researchers are testing for positive or negative bacteria.

Know More
What do biochemical tests determine?
Credit: Stanislaw Pytel Photodisc Getty Images

Full Answer

The Mannitol Salt Agar test (MSA) is widely used by biologists and chemists to test for the presence of gram-positive bacteria, such as Staph and Strep species. This test is classified as selective and differential: the main differential ingredient in the MSA is the sugar mannitol; this substance is used to attract organisms (gram-positive bacteria) that feed on mannitol as a food source. Upon consuming the substance, these bacteria produce acidic byproducts, also called fermentation, which ultimately lower the pH of the surrounding media. The varying degrees of acidity produced by the media are used as pH indicators, which range in color from red to orange and pale yellow. According to the University of Wyoming, oxidase tests are used to determine the presence of gram-negative bacteria, specifically the bacteria that contain the enzyme oxidase. In this test, positive results occur when electrons are oxidized by the cytochrome oxidase, which turns dark purple in color.

Sources:

  1. uwyo.edu

Is this answer helpful?

Similar Questions

  • Q:

    Why are biochemical tests used to identify bacteria?

    A:

    Biochemical tests are the quickest and easiest tests for identifying bacteria because they use deductive principles to reduce the number of possible species present very quickly. Additionally, because bacteria are microorganisms, visual identification is not always possible, and is never easy. Genetic testing is possible for some well-known bacteria, but it is expensive and time consuming.

    Full Answer >
    Filed Under:
  • Q:

    What do ninhydrin test results mean?

    A:

    A ninhydrin test is used to detect the presence of amino acids. During the test, which boils a solution of ninhydrin, if there are amino acids present, the solution turns a blue or purple color. Certain amino acids, such as proline and hydroxyproline, will turn the solution yellow. Ninhydrin spray is often used at crime scenes to make fingerprints visible because they contain trace amounts of amino acids.

    Full Answer >
    Filed Under:
  • Q:

    Why is iodine called an indicator?

    A:

    Iodine is known as an indicator because it changes color in the presence of starch and several other molecules. Iodine can also be used to track iodide and iodine in its elemental form.

    Full Answer >
    Filed Under:
  • Q:

    What causes the result of a Benedict's test to be positive?

    A:

    A positive Benedict's test is the result of the presence of reducing sugars. A positive Benedict's test will cause the solution used in the test to form reddish precipitate, according to Harper College.

    Full Answer >
    Filed Under:

Explore