The stem of a plant must elevate the flowers, fruits and leaves of the plant so that the plant can receive enough sunlight to undergo photosynthesis. The cells in the stem of a plant often have thicker cell walls than the other parts of the plant in order to A. Allow more light to penetrate through the stem B. Secrete water and oxygen through the stem C. Provide support and strength to the stem D. Increase gas exchange in the stem

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.

answer >   yes we do, women; have three holes, urethral opening(pee hole, vagina, and the women pee/girls pee out of the urethra like the men do; only they have a single opening to pee/ejaculate.   (sorry if i'm too forward with this, but this is for a biology class, isn't it? )

hope that !         : )

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.