Question

The diagram below represents the development of a human zygote from fertilization to the late blastocyst stage.

Select a correct statement from the following options

• A. If two sperms penetrate the oocyte membrane at the time of fertilization, conjoined twins with shared body parts will be born.
• B. During the process of in vitro fertilization with embryo transfer (IVF-ET), the embryo is transferred at the 2-cell stage to the mother’s uterus.
• C. The outer cells (structure A) of the early-blastocyst will eventually form the foetus.
• D. In ZIFT, the zygote with 8-cell stage is transferred into the fallopian tube.

Answer 1

The correct option is D

In ZIFT, the zygote with 8-cell stage is transferred into the fallopian tube.

If two sperms penetrate the oocyte membrane and fertilization occurs, then fraternal twins are born.
For IVF, followed by embryo transfer, embryo with more than 8 blastomeres is transferred into the uterus to complete its further development.
Inner cells mass of the early blastocyst will form the foetus.