Nucleic Acids - Mock Test 25

Question 241

Damage to DNA caused by ultraviolet radiation can be repaired by?

A) uvr ABC excinuclease B) DNA polymerase I C) DNA ligase D) All of these

---

No Details

Question 242

Exposure of DNA to ultraviolet radiation can lead to the formation of?

A) Adenine dimers B) Guanine dimers C) Thymine dimers D) Uracil dimers

---

No Details

Question 243

Nitrosamine can deaminate?

A) Cytosine to form uracil B) Adenine to form xanthine C) Guanine to form hypoxanthine D) All of these

---

No Details

Question 244

Mutations can be caused by?

A) Ultraviolet radiation B) Ionising radiation C) Alkylating agents D) All of these

---

No Details

Question 245

The coding sequences in lac operon include?

A) i gene B) i gene, operator locus and promoter C) z, y and a genes D) i, z, y and a genes

---

No Details

Question 246

The coding sequences in lac operon include?

A) i gene B) i gene, operator locus and promoter C) z, y and a genes D) i, z, y and a genes

---

No Details

Question 247

Expression of structural genes of lac operon is affected by all the following except?

A) Lactose or its analogues B) Repressor tetramer C) cAMP D) CAP-cAMP complex

---

No Details

Question 248

Lactose or its analogues act as positive regulators of lac operon by?

A) Attaching to i gene and preventing its expression B) Increasing the synthesis of catabolite gene activator protein C) Attaching to promoter region and facilitating the binding of RNA polymerase holoenzyme D) Binding to repressor subunits so that the repressor cannot attach to the operator locus

---

No Details

Question 249

Binding of RNA polymerase holoenzyme to the promoter region of lac operon is facilitated by?

A) Catabolite gene activator protein ( CAP ) B) cAMP C) CAP-cAMP complex D) None of these

---

No Details

Question 250

The enzymes encoded by z, y and a genes of lac operon are inducible, and their inducer is?

A) Lactose B) Allo-lactose C) Catabolite gene activator protein D) All of these

---

No Details