Stem cell research is an emotional topic. although the advancements in dna technology are remarkable, there are many arguments for and against stem cell research. which is an argument against stem cell research? a) stem cell research exploits fetuses and a mother's eggs. b) stem cell research could lead to the regeneration of skin for burn victims. c) researchers could use embryonic stem cells to find the cure to many different disorders and illnesses. d) stem cell research could lead to the regeneration of nerve cells and tissues to aid spinal cord injured patients.

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.