Which statement accurately describes the relationship between the brain and addiction?

a. all drugs act on dopamine synapses in the same way.
b. normal activities produce heightened responses once receptors are reduced.
c. the brain reacts to excessive dopamine levels by increasing the number of dopamine receptors.
d. a higher amount of addictive chemicals are needed to get the same high when fewer receptors are present

i just took the test the answer is "d"

In a cross between individuals of a species of tropical fish, all of the male offspring have long tail fins, and none of the females possess the trait. mating two of the f1 fish fails to produce females with the trait. explain the inheritance pattern of the trait.

The human genome project is devoted to mapping the general dna sequence of our species. this could lead to the development of new medicines, as well as the possibility of using gene therapy to treat certain diseases. however, there are some ethical issues surrounding the mapping of individual genomes. one concern is a) that your genes may change over time, making the project useless. b) that insurance companies could discriminate based on genetic make-up. c) that since this has never been done before, we should probably not do it now. d) that sequencing our individual genomes is so expensive, it is a counter-productive strategy.

Construct at least two possible hypotheses for the student’s experiment.