Understanding ELISA: A Quiz

What does ELISA stand for?

• Enzyme Linked Immunosorbent Assay

• Enzyme Linked Immunosorbent Analysis

• Enzyme Linked Immunosorbent Application

• Enzyme Linked Immunosorbent Activity

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DOK Level 1: Recall

Which of the following is the first step in an ELISA procedure?

• Adding the substrate

• Coating the plate with antigen

• Adding the enzyme-linked antibody

• Washing the plate

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DOK Level 1: Recall

In an ELISA, what is the purpose of the substrate?

• To bind to the antigen

• To bind to the primary antibody

• To produce a detectable signal

• To wash the plate

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DOK Level 1: Recall

Explain why washing steps are crucial in the ELISA procedure.

• To remove unbound substances and reduce background noise

• To increase the binding of the substrate

• To enhance the color development

• To stabilize the antigen-antibody complex

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DOK Level 2: Skill/Concept

Describe one application of ELISA in the medical field.

• ELISA is used to measure the pH of a solution.

• ELISA is used to detect the presence of specific antibodies in a patient's blood.

• ELISA is used to sequence DNA.

• ELISA is used to measure the boiling point of a liquid.

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DOK Level 2: Skill/Concept

Compare and contrast direct and indirect ELISA in terms of sensitivity and specificity.

• Direct ELISA is more sensitive but less specific than indirect ELISA.

• Indirect ELISA is more sensitive and more specific than direct ELISA.

• Direct ELISA is less sensitive but more specific than indirect ELISA.

• Indirect ELISA is less sensitive and less specific than direct ELISA.

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DOK Level 3: Strategic Thinking

Identify the common enzyme used in ELISA assays and explain its role.

• Amylase; it breaks down starch into sugars.

• Catalase; it decomposes hydrogen peroxide.

• Horseradish peroxidase (HRP); it catalyzes the oxidation of substrates to produce a color change.

• Lipase; it breaks down fats into fatty acids and glycerol.

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DOK Level 2: Skill/Concept

A student is performing an ELISA and observes no color change after adding the substrate. List two possible reasons for this observation.

• The substrate was not added, and the plate was not washed properly.

• The enzyme-linked antibody was added in excess, and the antigen was not present.

• The primary antibody was not added, and the substrate was not incubated long enough.

• The antigen was not present, and the enzyme-linked antibody was not added.

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DOK Level 3: Strategic Thinking

5.) In what order should you add the reagents to perform an ELISA test?

• a.) Primary antibody, antigen sample, enzyme-linked secondary antibody, substrate

• b.) Antigen sample, primary antibody, enzyme-linked secondary antibody, substrate

• c.) Substrate, enzyme-linked secondary antibody, antigen samples

• d.) Primary antibody, enzyme-linked secondary antibody, antigen samples, substrate

4.) During the ELISA test, the secondary antibody was attached to an enzyme. What happens when that enzyme becomes attached to the substrate?

• a.) The enzyme and the substrate reacted with the primary antibody and caused a color change.

• b.) The enzyme and the substrate work worked together to destroy the antigen, resulting in a color change.

• c.) The enzyme caused the substrate to change, resulting in a color change.

• d.) The substrate caused the enzyme to change, resulting in a color change.

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NGSS.HS-PS1-5