Elution is:

1. Separating the restricted DNA fragments on agarose gel.

2. Staining the separate DNA fragments with ethidium bromide

3. cutting out of the separated band of DNA from the agarose gel and extracting them from the gel piece.

4. constructing rDNA by joining the purified DNA fragments to the cloning vector.

When isolating the pure DNA from a bacterial cell, the cell should not be treated with:

1. lysozyme

2. proteases

3. ribonuclease

4. deoxyribonuclease

A host cell normally does not take up a foreign DNA until it has been made competent to do so. This is because:

1. DNA is a hydrophilic molecule

2. DNA is a very large molecule

3. there are no receptors for DNA on the cell membrane

4. DNA is an inert molecule

Taq polymerase is used in the polymerase chain reaction because:

1. It replicates DNA faster than other enzymes

2. It is the only enzyme that can replicate DNA invitro

3. It does not require an RNA primer to function

4. It is thermostable 

The first type II restriction endonuclease discovered that could cut dsDNA specific site was:

1. EcoRI

2. SmaI

3. Hind II

4. Hind III

Which statement regarding restriction endonucleases is NOT correct?

1. They recognize a specific base sequence in the DNA.

2. They are produced by bacterial cells as a primitive immune system.

3. They digest DNA by removing nucleotides from a free 3' end.

4. They often generate stick ends.

What limitation of traditional hybridization used for plant and animal breeding has been overcome by

the use of rDNA techniques?

1. High cost

2. Insertion of undesirable genes

3. Complexity of the procedure

4. Antigenicity of the product

Which of the following restriction sites is located within the gene for tetracycline resistance in the plasmid pBR322?

1. BamHI

2. Psti

3. Clal

4. Pvull

The technique not used for transformation of plant cells in recombinant procedures is:

1. Biolistics

2. Agrobacterium mediation

3. Use of viruses

4. Micro-injection

In the screening process during rDNA experiments, clones that metabolize $\beta$-gal turn:

1. Colorless

2. Blue

3. Yellow

4. Green