Dietary factors are now being studied for how they regulate human gene activity and how this contributes to disease. for example, how does a diet high in unsaturated fatty acids maintain a healthy blood lipid profile? within hours of feeding animals food rich in polyunsaturated fatty acids (pufas), there is an increase in the activity of genes responsible for making enzymes that break down fats, and a reduction of the activity of genes responsible for making enzymes that make fats. this has the effect of changing fat metabolism, which leads to a lowering of blood lipid levels. the control of what type of dna sequence would pufas most likely be affecting?

a. operator sequences
b. intron sequences
c. signal sequences
d. enhancer sequences

D. Enhancer sequences

Explanation:

PUFAs are most likely affecting the control of enhancer sequences in the DNA.

Enhancer sequences are regulatory DNA sequences that when bound by specific proteins called transcription factors, enhance the transcription of an associated gene.

PUFAs binds to these  specific activator proteins which in turn binds with these enhancers and modify or change the level of transcription.

An operator sequence is a genetic sequence which allows proteins responsible for transcription to attach to the DNA sequence. Operation sequences are bound by variety of transcription factors, and not directly  by dietary substances.

An intron is any nucleotide sequence within a gene that is removed by RNA splicing during maturation of the final RNA product. Intron sequences are spliced out and unless they contain enhancers within them, cannot regulate expression of genes.

Signal sequences target proteins to their respective localizations, as such they have no influence on gene expression.

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.