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?

#Question id: 11414

#Unit 10. Ecological Principles

Which of the following combination of species feature that affecting a species’ sensitivity to extinction?

#Question id: 11415

#Unit 10. Ecological Principles

Below is a list of various bird groups, with their typical age at maturity (in years). Which of these would you expect to have the greatest annual survival?

#Question id: 11416

#Unit 10. Ecological Principles

Which of the following biomes spans the largest annual mean temperature range, but the narrowest mean precipitation range?

#Question id: 11417

#Unit 10. Ecological Principles

Use the following figure to answer the question below

Which of the following name of biome 5, 6, 4 and 3 respectively?

#Question id: 11418

#Unit 10. Ecological Principles

Use the following diagram of five islands formed at around the same time near a particular mainland, as well as MacArthur and Wilson's island equilibrium model principles

Which island would likely have the lowest extinction rate?

#Question id: 11419

#Unit 10. Ecological Principles

There are more species in tropical areas than in places more distant from the equator. This is probably a result of

a) more predators and parasites

b) more dispersed annual solar radiation compared to the poles

c) more frequent ecological disturbances over a longer time span

d) a longer time frame without disturbances for evolution and speciation