Which of the following statements about the nucleus is true? a. the nucleus is the site of protein assembly. b. the nucleus is surrounded by cell membrane that lets materials in and out. c. the nucleus stores the coded instructions for making the cell’s proteins. d. the nucleus usually contains a nucleolus region which is where mitochondria assembly begins.

Acar company is testing seatbelts using crash test dummies. the company finds that when cars come to a sudden stop, the crash test dummies' bodies continue to move forward. the seat belt keeps the crash test dummies from hitting the back of the seat in front of them. why do the crash test dummies' bodies continue to move forward even though the car stopped? a. the friction opposing their bodies' movement keeps them in motion. b. the inertia of their bodies keeps them in motion. c. the forward acceleration of the car keeps them in motion. d. the gravity pulling on the car keeps them in motion.

Keeping in mind the life cycle of bacteriophages, consider the following problem: during the reproductive cycle of a temperate bacteriophage, the viral dna inserts into the bacterial chromosome where the resultant prophage behaves much like a trojan horse. it can remain quiescent, or it can become lytic and initiate a burst of progeny viruses. several operons maintain the prophage state by interacting with a repressor that keeps the lytic cycle in check. insults (ultraviolet light, for example) to the bacterial cell lead to a partial breakdown of the repressor, which in turn causes the production of enzymes involved in the lytic cycle. as stated in this simple form, would you consider this system of regulation to be operating under positive or negative control?

Explain how scientists use geologic time to determine the age of landforms.