Inside each of your lungs there are tubes called bronchi. these branch into even smaller tubes much like the branches of a tree. what are at the ends of these tubes?

Small air sacs.

Explanation:

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.

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.