The need for energy, gained by respiration and photosynthesis, is the driving force of the oxygen cycle.

idk why hjggjhjkhj

both male and female gametes are produced by meiosis of the germ cells. therefore, both male and female gametes are haploid. one male and one female gamete unite during the fertilization to form the diploid zygote. in seed bearing plants, pollen grain is the male gametophyte, which produces sperm cells.

i think the answer is composed of atoms