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 have isolated a mutation that causes constitutive melibiase activity, which you designate MelA–. P1 phage mapping experiments using a Tn5 insertion linked to Mel1 show that MelA– is not linked to Mel1. Moreover you find that when an amber suppressor is introduced into a MelA– mutant, normal melibiase regulation is restored. Classify the MelA– mutation in terms of its basic genetic properties, 

#Question id: 10997

#Unit 7. System Physiology – Animal

A 60-year-old woman has a resting heart rate of 70 beats/min, arterial pressure is 130/85 mm Hg, and body temperature is normal. Her pressure-volume diagram of the left ventricle is shown above.

What is her cardiac output in milliliters per minute?

#Question id: 4980

#Unit 11. Evolution and Behavior

If an increase in dicynodont species diversity (i.e., number of species) occurred soon after the Permian extinction, and if it occurred for the same general reason usually given for the increase in mammalian diversity following the Cretaceous extinction, then it should be attributed to

#Question id: 3401

#Unit 11. Evolution and Behavior

Genotypes of leopard frogs from a population in central Kansas were determined for a locus that encodes the enzyme malate dehydrogenase. The following numbers of genotypes were observed: What would be the expected numbers of genotypes if the population were in Hardy-Weinberg equilibrium?

#Question id: 10629

#Unit 10. Ecological Principles

Following are density dependent factors

A- Food                            B- space

Which of the following animal and their most important density dependent limiting factor are correct?

#Question id: 18945

#Unit 13. Methods in Biology