Tools and Techniques

Ethidium bromide (EtBr) is used for staining DNA. It intercalates between DNA bases and fluoresces under UV light, so it helps visualise the DNA molecules after electrophoresis.

The correct matches from the chapter are:

- Engvall and Perlman — ELISA
- Robert Hooke — Microscopy
- Sanger — DNA sequencing

Since more than one match is correct, this is a multiple correct question.

The chapter says mass spectrometry is used to identify unknown compounds, quantify unknown materials, and elucidate structure and chemical properties of molecules. Therefore, the correct option is All of the above.

From the chapter:

- Direct ELISA: antigen is coated/bound on the plate and enzyme-conjugated antibody binds directly.
- Indirect ELISA: bound antigen with only one labeled secondary antibody used.
- Sandwich ELISA: antigen is bound between a captured antibody and a labeled secondary antibody.

So the intended matches are correct overall.

In DNA gel electrophoresis, larger fragments remain near the wells, while smaller fragments move farther toward the positive end. So:

- I is correct
- III is correct
- II is false
- IV is false

Hence, the correct option is I and III.

For a resolved image of the surface of an object, the chapter says scanning electron microscopy gives a highly magnified and resolved image of the object surface. So the correct microscope is the scanning electron microscope.

The correct matches are:

- Engvall and Perlman — ELISA
- Robert Hooke — Microscopy
- Sanger — DNA sequencing

So the full matching set is the correct answer.

The chapter says DNA microarray is used to analyse a large number of DNA fragments in parallel for quantification of the expression of a large number of genes. So the correct answer is Microarray.

This is a subjective question asking to differentiate between three pairs of microscopy techniques. A complete answer should compare each pair:

- SEM and TEM: SEM shows the surface of an object, while TEM uses electrons passing through an ultra-thin specimen to show internal details.
- Dark field and bright field microscopy: bright field uses direct light and usually stains, while dark field blocks central light and gives a bright image on a dark background.
- Phase contrast and confocal microscopy: phase contrast enhances contrast in transparent specimens by changing phase/amplitude of light, while confocal microscopy uses fluorescently labelled specimens and gives sharp high-resolution images of fixed cells/tissues.