Lactational Amenorrhea as Contraception — NEET Biology

Correct answer: B — S3, S4 and S5 are NOT correct.

This question tests the understanding of ZIFT and its distinctions from other ARTs and natural reproductive processes. S1: Correct. NCERT states, "The zygote or early embryos (with upto 8 blastomeres) could then be transferred into the fallopian tube (ZIFT–zygote intra fallopian transfer)." S2: Correct. The fallopian tube is indeed the natural site for fertilization and the initial stages of embryo development before it reaches the uterus. ZIFT places the early embryo there to follow this natural pathway. S3: Incorrect. NCERT specifies, "...embryos with more than 8 blastomeres, into the uterus (IUT – intra uterine transfer)". Thus, embryos with more than 8 blastomeres are transferred to the uterus, not the fallopian tube. S4: Incorrect. NCERT states, "Embryos formed by in-vivo fertilisation (fusion of gametes within the female) also could be used for such transfer to assist those females who cannot conceive." This means ZIFT (or IUT) can be used for both *in vitro* and *in vivo* formed embryos. S5: Incorrect. Infertility due to the female's inability to produce ova is addressed by GIFT (Gamete Intra Fallopian Transfer) using donor ova, where the gamete is transferred, not a zygote/embryo. ZIFT is for transferring an already formed zygote or early embryo. Statements S3, S4, and S5 are NOT correct. The final answer is B because it accurately identifies S3, S4, and S5 as the incorrect statements regarding ZIFT and related procedures.