Fill in the blanks:
a. Zygote divides to form ...1... which is implanted to uterus.
b. The structure which provides vascular connection between foetus and uterus is called ..2...
c. Inner cell mass contains certain cells called ...3... which have the potency to give rise to all the tissues and organs.
d. By the end of ...4..., most of the major organ systems are formed, for example, the limbs and external genital organs are well -developed.
e. Immediately after implantation, the ...5... differentiates into an outer layer called ectodern and an inner layer called endoderm.

Options

A. 1-morula, 2-umbilical cord, 3-trophoblast, 4-second trimester, 5-stem cells
B. 1-blastocyst, 2-placenta, 3-stem cells, 4-first trimester, 5-trophoblast
C. 1-blastocyst, 2-umbilical cord, 3- stem cells, 4-second trimesters, 5-inner cell mass
D. 1-blastocyst, 2-placenta, 3-stem cells, 4-first trimester, 5-inner cell mass.

Answer

D

Explanation

a. Zygote divides to form blastocyst which is implanted to uterus.
b. The structure which provides vascular connection between foetus and uterus is called placenta.
c. Inner cell mass contain certain cells called stem cells which have the potency to give rise to all the tissues and organs.
d. By the end of first trimester, most of the major organ systems are formed, for example, the limbs and external genital organs are well-developed.
e. Immediately after implantation, the inner cell mass differentiates into an outer layer called ectoderm and an inner layer called endoderm. 1