You are studying regulation of a prokaryotic operon. Experiments show that expression of the operon is increased when levels of biosynthetic product from that pathway are low. Based on this information, what is a likely mode of regulation?
A. The product binds to the biosynthetic enzymes, blocking them directly.
B. The product binds a repressor, preventing it from binding the operator.
C. The product binds an activator, helping RNA polymerase to bind the promoter.
D. The product binds a repressor, allowing it to bind the operator.
Answer: D
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A person suffers injury in a car accident, loses a serious amount of blood, and is in danger of going into shock from low blood pressure. Discuss what effect such an injury would have on the production of ADH, aldosterone, atrial natriuretic factor, angiotensin, and erythropoietin
What will be an ideal response?
The increased reliance on genetically engineered crops grew from the need to ____
a. develop new species of crop plants b. provide farmers with more expensive seeds c. find new pesticides d. produce more food at lower cost without harming the environment
e. find more ways to profit from crop plantsHow many different species of Plasmodium cause malaria?
a. two b. three c. four d. five
Adult giraffes can be up to 20 ft. tall, and thus require special adaptations to maintain appropriate blood pressure. One adaptation is the rete mirabile, a group of blood vessels that form a web or net-like structure to slow blood flow.The giraffe, as the tallest living land animal, has several adaptations for its height. To prevent blood from pooling in the head when it bends down to drink, the jugular veins of a giraffe have multiple one-way valves. Furthermore, a web of arteries and veins in the neck called the rete mirabile ("wonderful net") slows the flow of blood into the brain. These specializations of the ________ act as mechanisms to maintain ________.
A. circulatory system; blood pressure homeostasis B. nervous system; temperature homeostasis C. circulatory system; pH homeostasis D. nervous system; homeothermy