Which of the following describes a fertilized egg as it relates to new tissue development?

The term that describes a fertilized egg in the context of new tissue development is "zygote." When the sperm and ovum fuse during fertilization, they form the zygote, which is the initial cell that marks the beginning of the development of a new organism. The zygote undergoes numerous divisions and differentiations to develop into an embryo, which comprises various tissues and organs as development continues.

While "embryo" is also related to new tissue development, it refers specifically to the stage that occurs after the zygote has begun to divide and differentiate. A "germ" typically refers to germ cells involved in the reproductive process and not the fertilized egg itself. "Gametes" are the haploid cells—sperm and eggs—that combine during fertilization to create the zygote, but they are not yet involved in the development of an organism's tissues. Therefore, zygote is the most accurate term regarding the fertilized egg's role in new tissue development.