Second layer of the cell membrane called

the answer is b.) hydrogen bonds between bases.

trachea, alveoli, lung capillaries, arteries

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.