Final answer:
In conifer reproduction, pollen grains are released into the air, where they can be carried by the wind to fertilize female cones. The diploid zygote is formed after fertilization of the female gamete by the male gametes in the pollen.
Step-by-step explanation:
During conifer reproduction, pollen grains are released into the air. Male cones produce pollen grains that are carried by the wind to the female cones. Female cones are usually found in the upper branches of the tree, where they can be fertilized by the airborne pollen. Once the pollen reaches a female cone, it slides between the open scales to a space next to the micropylar canal, where it is rehydrated by a liquid secreted by the ovule. This process allows for the eventual fertilization of the female gamete by the male gametes in the pollen grains. The diploid zygote is formed when fertilization occurs, leading to seed development and completing the conifer life cycle.