An important limitation to the use of Agrobacterium tumefaciens is that it can not:
1. infect dicots
2. be genetically modified
3. be cultured on a nutrient medium
4. infect crop plants such as wheat and corn
Answer 4. Most of the important crops are monocots such as cereals.
Identify a character that is not desirable in a cloning vector:
1. an inactive promoter
2. an origin of replication site
3. selectable markers such as genes for antibiotic resistance
4. one or more unique restriction endonuclease sites
(1) An inactive promoter will not allow gene expression.
A cloning vector has two antibiotic resistance genes- for tetracycline and ampicillin. A foreign DNA
was inserted into the tetracycline gene. Non-recombinants would survive on the medium containing :
1. ampicillin but not tetracycline
2. tetracycline but not ampicillin
3. both tetracycline and ampicillin
4. neither tetracycline nor ampicillin
(3) Both genes are functional in non-recombinants. In recombinants the gene for tetracycline resistance would be insertionally inactivated.
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.
Answer 3. Read page 198, XII NCERT
When isolating the pure DNA from a bacterial cell, the cell should not be treated with:
(4) This will digest the DNA.
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
(1) Cell membrane is made of a phospholipid bilayer and allows only lipid soluble substances to diffuse across it.
The first type II restriction endonuclease discovered that could cut dsDNA specific site was:
3. Hind II
4. Hind III
Answer 3. read page 195, XII NCERT
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.
3. Read page 196, XII NCERT
The first type II restriction endonuclease discovered that could cut dsDNA at specific site was:
1. EcoRI 2. SmaI
3. Hind II 4. Hind III
3. Read page 195, XII NCERT
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
page 194, Xll NCERT