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.

You next construct a MelA– MelB– double mutant, which gives the following behavior:

 

Which of your two models is consistent with this new data?

a) the MelA- MelB- double mutant is identical to the MelB- mutant

b) MelA- is epistatic to MelB-

c) MelB- is epistatic to MelA-

d) the MelA- MelB- double mutant is identical to the MelA- mutant

Which of the following is the correct prediction about the double mutants?

#Question id: 11055

#Unit 10. Ecological Principles

Poison arrow frogs have brightly coloured skin patterns of blue, orange, yellow and red. This skin adornment is an example of what kind of defense against predation?

#Question id: 11056

#Unit 10. Ecological Principles

The "dead-leaf" butterfly is aptly named. This is an example of what kind of defense against predation?

#Question id: 11057

#Unit 10. Ecological Principles

Bombardier beetles release an explosive mixture of quinones and hydrogen peroxide from glands at the end of their abdomen when disturbed by grasshopper mice and other predators. This is an example of what kind of defense against predation?

#Question id: 11058

#Unit 10. Ecological Principles

The pufferfish, a common marine fish, has extensive spines that extend outward when it swallows water, becoming several times its normal size. This is an example of what kind of defense against predation?

#Question id: 11169

#Unit 10. Ecological Principles

The viceroy butterfly (limenitis archippus) resembles the queen butterfly (danaus gilippus), a species toxic to birds because of alkaloids it stores during larval development from the milkweeds it feeds upon. The viceroy butterfly is an example of what kind of defense against predation?

#Question id: 11170

#Unit 10. Ecological Principles

Which of the following examples is not a behavioural defense against predators?