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Question
When a fertilised egg E formed in the oviduct of a human female divides repeatedly to form an embryo, the embryo gets implanted in the thick and soft lining of the uterus. After this a disc-like special tissue T develops between the uterus wall and embryo through which all the requirements of the developing embryo (and foetus) are met from the mother's body, The embryo is connected to the tissue T through a string like structure S.
(a) What is the other name of fertilised egg cell E?
(b) What is the name of tissue T?
(c) Name the string-like structure S.
(d) Name two substances which pass from mother's blood to embryo through tissue T and, one type of substance which passes from embryo to mother's blood.
(e) What happens to S when the baby is born? Why?
Solution
(a) The fertilised egg cell E is also called the zygote.
(b) The tissue T is the placenta.
(c) The string-like structure S is the umbilical cord.
(d) Oxygen and nutrients pass from the mother's blood to the embryo and carbon dioxide passes from the embryo to the mother's blood through the placenta (T).
(e) When a baby is born, the umbilical cord is still attached to the baby. It is cut and tied to separate the baby from the mother.
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