Organelles help to maintain homeostasis in cells. Human cells are no exception. White blood cells have the important role of engulfing or “eating” viruses and bacteria that can make us sick. Out of the organelles listed, which one do you think white blood cells have more of then others? a) Lysosomes because these are filled with digestive enzymes
b) Vacuoles because these can store materials
c) Ribosomes because these help to build proteins
d) Mitochondria because these help to create energy

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.