A compound known as X-gal is widely used in molecular genetic research. When wild-type (normal) E. coli is grown on medium containing X-gal, the bacterial colonies turn blue. In contrast, when lacZ mutants are grown on medium containing X-gal
, the bacterial colonies remain their normal white color. X-gal is likely to be a compound _____.
A) chemically similar to glucose
B) chemically similar to galactose
C) chemically similar to lactose
D) that cannot be transported into lacZ mutants
E) that can be transported only into lacA mutants
Answer: C
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Sugars and phosphates are held together in a DNA molecule by a(n) ____________________ bond
Fill in the blank(s) with correct word
Meiosis and Changes in Number of Chromosomes
What will be an ideal response?
Claytonia virginica is a woodland spring herb with flowers that vary from white to pale pink to bright pink
Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical differences between the two), and plants experiencing severe herbivory are more likely to die. The bees that pollinate this plant also prefer pink to white flowers, so that Claytonia with pink flowers have greater relative fruit set than Claytonia with white flowers. A researcher observes that the percentage of different flower colors remains stable in the study population from year to year. Given no other information, if the researcher removes all slugs from the study population, what do you expect to happen to the distribution of flower colors in the population over time? A) The percentage of pink flowers should increase over time. B) The percentage of white flowers should increase over time. C) The distribution of flower colors should not change. D) The distribution of flower colors should randomly fluctuate over time.
Soon after amniotic vertebrates appeared, two different evolutionary lineages began to diverge. They are:
a. the mammals and the reptiles. b. the mammals and the birds. c. the reptiles and the birds. d. the amphibians and the reptiles. e. the crocodiles and the birds.