Which of the following statements about the selection pressure is incorrect?

a.If survival of juveniles and adult is poor then selection favours a single act of reproduction

b.If survival of juveniles and adult is poor and unpredictable then selection favours repeated reproduction and long reproductive life

c.If the environment is stable then selection favours a single act of reproduction.

d.If survival of juveniles is very poor and unpredictable but adult are more likely to survive then selection favours repeated reproduction and long reproductive life

e.If survival of adult is unpredictable but juveniles are more likely to survive then selection favours a single act of reproduction

#Question id: 3979

#Unit 3. Fundamental Processes

“Housekeeping genes” in bacteria are commonly expressed constitutively, but not all of these genes are expressed at the same level (the same number of molecules per cell).  The primary mechanism responsible for variations in the level of constitutive enzymes from different genes is that:

#Question id: 3980

#Unit 3. Fundamental Processes

Which of the following statements correctly describes promoters in E. coli?

#Question id: 3981

#Unit 3. Fundamental Processes

The diagram below represents a hypothetical operon in the bacterium E. coli.  The operon consists of two structural genes (A and B), which code for the enzymes A-ase and B-ase, respectively, and also includes P (promoter) and O (operator) regions as shown.

 When a certain compound (X) is added to the growth medium of E. coli, the separate enzymes A-ase and B-ase are both synthesized at a 50-fold higher rate than in the absence of X.  (X has a molecular weight of about 200.)  Which of the following statements is true of the operon decribed above?

#Question id: 3982

#Unit 3. Fundamental Processes

The diagram below represents a hypothetical operon in the bacterium E. coli.  The operon consists of two structural genes (A and B) that code for the enzymes A-ase and B-ase, respectively, and also includes P (promoter) and O (operator) regions as shown.

 When a certain compound (X) is added to the growth medium of E. coli, the separate enzymes A-ase and B-ase are both synthesized at a 50-fold higher rate than in the absence of X (which has a molecular weight of about 200).  Which one of the following statements is true of such an operon?

#Question id: 3983

#Unit 3. Fundamental Processes

Transcription of the lactose operon in E. coli is stimulated by:

#Question id: 3984

#Unit 3. Fundamental Processes

Which of the following statements about regulation of the lac operon is true?