Question

Am embryo is made up of a single cell
A. True
B. False

Answer 1

Hint: An embryo is an early stage of development in living organisms, mainly in animals. When two gametes fuse, the process is called fertilization. Fertilization leads to the formation of a zygote, which then leads to the formation of a complete organism.

Complete answer: The male and female gamete fuses with each other during copulation. The male gamete (sperm) and female gamete (ovum) fuses with each other to form a diploid zygote. During copulation, millions of sperm cells enter into the uterus of the female. All sperms move forward towards the egg (ovum). Out of a million sperms, only one sperm fuses with the ovum. When the sperm fuses with an ovum, the zygote is formed, which is single-celled. These single cells then differentiate further and form the embryo, which is the first stage of embryonic development. Therefore, a zygote is formed of a single cell, which then differentiates and forms an embryo. Reproduction is carried out by reproductive organs. They are of two types; primary reproductive organs and accessory reproductive organs. Primary organs refer to those organs that take part directly in the reproduction process, i.e. gonads (the sperm and egg cell). On the other hand, accessory organs refer to those that help in reproduction indirectly. When the zygote is formed, it differentiates further to form a sixteen celled zygote. It then moves towards the uterus, till then it forms a small hollow ball of numerous cells called the blastocyst. The blastocyst forms a pit in the wall of the uterus and later gets fixed on the wall of the uterus.
Hence, the correct answer is option B.

Note: The growing embryo is also known as a foetus. It needs oxygen and nutrients to grow further. It receives all its important components from the mother through the placenta. It also excretes out nitrogenous wastes and carbon dioxide through the placenta. The placenta is a disc-like structure attached to the uterine wall. A cord of blood vessels joining the foetus with the placenta is called an umbilical cord.