Dioxin, produced as a by-product of various industrial chemical processes, is suspected of contributing to the development of cancer and birth defects in animals and humans. it apparently acts by entering cells by simple diffusion and binding to proteins in the cytoplasm, then altering the pattern of gene expression. which of the following are likely to be the cytoplasmic proteins to which dioxin binds? a. nucleosomes
b. dna polymerases
c. enhancers
d. transcription factors
e. growth factor receptors

d. transcription factors

Explanation:

Transcription factors are the proteins present in cells that are involved in the regulation of gene expression. The transcription factors may increase or decrease the expression of a gene. Therefore, a transcription factor may serve as an activator or repressor for a gene. These proteins bind to a regulatory sequence present near or within a gene, interact with RNA polymerase or other transcription factors and thereby, affect the transcription initiation.

Since binding of dioxin to certain proteins alter the pattern of gene expression in the cells, these proteins are the transcription factors. For instance, dioxin may bind to a transcription factor and up-regulate the expression of genes which in turn regulate the cell division.  

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.