Sexual reproduction in plants Reproduction in plants relies on pollination, where pollen produced by a plant being transferred from the male to female reproductive organs, for example, microsporangium to ovule in gymnosperms, and anther to stigma in angiosperms. In angiosperms, after pollination occurs a pollen tube protrudes from the pollen grain and grows down through the stigma, style, and ovary entering the ovule. This allows fertilization to occur and development to begin. Carpel Sexual reproduction in animals Sexual reproduction in animals utilizes either external or internal fertilization. External fertilization occurs outside the body of the female.
Internal fertilization occurs inside the body of the female.
All terrestrial animals utilize internal fertilization, whereas most aquatic animals with the exception or marine mammals and some sharks utilize external fertilization. The presence of water is the major factor in whether internal or external fertilization is utilized. Conjugation is a process by which some lower animals like paramecium can exchange nuclear material between two individuals. Development starts at the time of fertilization when a zygote forms in the fallopian tubes. The zygote forms a protective membrane called a fertilization membrane which prevents any more sperm from penetrating the egg cell.