Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 13712
TLS Online TPP Program

#Question id: 15656

You are studying a new strain of E. coli that can utilize the disaccharide melibiose very efficiently. You find that utilization depends on the enzyme melibiase, which is encoded by the gene Mel1. Mel1 is not expressed unless melibiose is present in the growth medium. Explain the two regulatory pathways for Mel1 that can explain the behavior of the MelA– and MelB– mutations. For each regulatory pathways what is a role for the inducer melibiose?

#Unit 13. Methods in Biology
  1. melibiose and MelB both have a net negative effect on Mel1 activity, and MelA has a net positive effect on Mel1 activity.
  2. melibiose and MelB both have a net positive effect on Mel1 activity, and MelA has a net negative effect on Mel1 activity.
  3. melibiose and MelB both have a net positive effect on Mel1 activity, and MelA also has a net positive effect on Mel1 activity.
  4. melibiose and MelB both have a net negative effect on Mel1 activity, and MelA also has a net negative effect on Mel1 activity.
More Questions
TLS Online TPP Program

#Question id: 5005

#Unit 11. Evolution and Behavior

Fossilized stromatolites
TLS Online TPP Program

#Question id: 15743

#Unit 5. Developmental Biology

Which of the following  hormone secretes from the developing Sertoli cells, during embryonic development, that blocks development of the female ducts?
TLS Online TPP Program

#Question id: 18658

#Unit 13. Methods in Biology

when the separation of protein takes place based on their isoelectric point, the technique known as 
TLS Online TPP Program

#Question id: 2244

#Unit 2. Cellular Organization

Arrange the statements below in the proper sequence of events that occur in an action potential:

I. The resting potential is re-established.

II. A stimulus depolarizes the membrane to threshold.

III. Na+ gates open and Na+ rushes into the cell.

IV. K+ gates open and K+ rushes out of the cell.
TLS Online TPP Program

#Question id: 19283

#Unit 9. Diversity of Life Forms

Which of the following most closely represents the male gametophyte of seed-bearing plants?