Wild type E. coli metabolizes the sugar lactose by expressing the enzyme ß-galactosidase. You have isolated a mutant that you call lac1-, which cannot synthesize ß-galactosidase and cannot grow on lactose (Lac-). During an condition  isolate  a second Lac– mutation, which you designate lac2-. Using P1 phage on this strain and use the resulting phage lysate to infect the lac2- strain, selecting for   Kanr   transductants. In this case, all 100   Kanr   transductants that are examined are Lac–. What does this result tell you about the relationship between the lac1- and lac2- mutations?

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#Question id: 5397

#General Aptitude

The average monthly income of P and Q is Rs.5050. The average monthly income of Q and R is Rs.6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is:

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#Question id: 15303

#Unit 4. Cell Communication and Cell Signaling

Neurofibromatosis, a benign tumor of the sheath cells that surround nerves, is caused by

a.  Loss of both alleles of NF1

b.  Mutation in RAS GAP-type protein

c.  A single mutant NF1 allele

d.  Mutation in SRC protein

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#Question id: 4236

#Unit 3. Fundamental Processes

In bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. Which of the following statements explains this fact?

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#Question id: 4321

#Unit 3. Fundamental Processes

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?

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#Question id: 7003

#Unit 5. Developmental Biology

What structural adaptation in chickens allows them to lay their eggs in arid environments rather than in water?