Ribozymes are ________
a. laboratory-formed selectively permeable vesicles
b. catalytic RNAs
c. fossils of an early eukaryote
d. dome-shaped layered structures formed by marine bacteria
b
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A team of researchers has developed a poison that has proven effective against lamprey larvae in freshwater cultures. The poison is ingested and causes paralysis by detaching segmental muscles from the skeletal elements
The team wants to test the poison's effectiveness in streams feeding Lake Michigan, but one critic worries about potential effects on lancelets, which are similar to lampreys in many ways. Why is this concern misplaced? A) A chemical poisonous to lampreys could not also be toxic to organisms as ancestral as lancelets. B) Lamprey larvae and lancelets have very different feeding mechanisms. C) Lancelets do not have segmental muscles. D) Lancelets live only in saltwater environments. E) Lancelets and lamprey larvae eat different kinds of food.
Skin color is an example of a human trait influenced by natural selection. What factor(s) has/have directly shaped variation in skin color? Select all that apply
A. temperature B. disease C. diet D. intensity of sunlight
Which of the following is filtered from blood but NOT normally found in urine?
a. water b. red blood cells c. H+ d. amino acids e. urea
Which of the following enzymes are produced by microorganisms on an industrial scale?
A. Keratinase B. Pectinase C. Cellulase D. Amylase E. All of the choices are correct.