The first informational molecule probably was ________
a. phospholipid
b. RNA
c. DNA
d. protein
b
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One function of HCl secreted in the stomach is to convert pepsinogen into the active enzyme pepsin. Why don't stomach cells simply secrete pepsin instead?
A. Adequate amounts of pepsin are already manufactured by the pancreas. B. Only the pepsinogen version is able to stabilize fat-water emulsions. C. Pepsin is denatured and rendered inactive in solutions with low pH. D. If cells produced active pepsin, they would digest their own cellular proteins.
Which groups of organisms are the most successful air breathing land invertebrates?
a. Frogs b. Snails c. Lobsters d. Spiders e. Birds
To best isolate mutant bacteria that are threonine auxotrophs from a larger population, threonine-rich media should be inoculated and any colonies that form are presumptive auxotrophic mutants.
Answer the following statement true (T) or false (F)
After the drought of 1977, researchers on the island of Daphne Major hypothesized that medium ground finches that had large, deep beaks, survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. If this hypothesis is correct, what would you expect to observe if a population of these medium ground finches colonizes a nearby island where Tribulus cistoides is the most abundant food for the next 1000 years? Assume that (1 ) even the survivors of the 1977 drought sometimes had difficulty cracking the tough T. cistoides fruits and would eat other seeds when offered a choice; and (2 ) food availability is the primary limit on finch fitness on this new island.
A) evolution of yet larger, deeper beaks over time B) evolution of smaller, pointier beaks over time C) random fluctuations in beak size and shape D) no change in beak size and shape