Acertain regulatory gene is involved in controlling the expression of other genes. in studying this regulatory gene, a scientist discovers that it encodes for an enzyme that causes histone deacetylase (the removal of acetyl groups from histone tails). based on this information, how would you predict that this enzyme regulates gene expression? a. it causes tighter packing of the chromatin at the target gene to inhibit translation. b. it causes decompression of the chromatin at the target gene to inhibit translation. c. it activates gene promoters to signal for the biding of rna polymerase. d. it activates rna processing by removing introns and splicing exons together.

On a backpacking trip, kenny hikes all day at a steady pace, covering 30 kilometers and burning 4000 calories. at the school track, janelle runs the 100-meter sprint in 13.5 seconds, burning 10 calories. afterward, janelle’s leg muscles are aching and she is breathing hard, while kenny maintains normal breathing all day, even though he burns 400 times more calories than janelle. which two statements offer the best explanation for this phenomenon? a. if the aerobic pathway—cellular respiration—cannot meet the energy demand, then the anaerobic pathway—lactic acid fermentation—starts up, resulting in lactic acid buildup and "oxygen debt." b. aerobic cellular respiration produces more energy, but its use is limited because of lactic acid buildup in the muscles and the resulting "oxygen debt." c. after about 90 seconds of intense exercise, the muscles become depleted of oxygen, and anaerobic respiration can no longer function to produce atp, resulting in "oxygen debt." d. the rate of energy demand determines how the muscles will obtain energy, either from cellular respiration or from lactic acid fermentation if not enough oxygen is present.