In most sexually reproducing organisms, the diploid phase of the life cycle begins at
A) spore formation.
B) gamete formation.
C) meiosis.
D) mitosis.
E) fertilization.

Question

Quizplus · Accepted Answer

The diploid phase of the life cycle begins at fertilization, where the haploid gametes fuse and form a diploid zygote. The zygote then undergoes mitosis to form a multicellular diploid organism. Option A refers to organisms that undergo alternation of generations, where the diploid phase does begin at spore formation. Option B refers to the formation of haploid gametes, which are not yet diploid. Option C refers to meiosis, which leads to the formation of haploid cells. Option D refers to mitosis, which occurs after the diploid phase has already begun.

In Most Sexually Reproducing Organisms, the Diploid Phase of the Life