In matter flows from one trophic level to another, and
elements are recycled within and among ecosystems.
1. biogeochemical
cycles
2. nutrients
3. nitrogen
fixation
4. denitrification
5. limiting nutrient

i think the answer would d

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.