3. Given below are the names of certain stages/substances related to reproduction and found in human body. Answer the questions related to them,
3. Given below are the names of certain stages/substances related to reproduction and found in human body. Answer the questions related to them,

(a) Foetus
(i) Where is it contained?

(ii) How does it differ from embryo?

(b) Hyaluronidase
(i) Is it an enzyme or simply a protein?

(ii) What is its function?

(c) Morula
(i) What is this stage?

(ii) Name the stage which comes next to it.

(d) Amniotic fluid
(i) Where is it found?

(ii) What are its functions?

(e) Placenta

(i) What are the two sources that form placenta?

(ii) Name any two main substances which pass from foetus to mother through placenta.

(iii) Name any two hormones it produces.

(f) Implantation

(i) The development stage that undergoes this process

(ii) The approximate time after fertilization, when it occurs.

Solution:-

(a)

(i) Foetus is contained in the uterus.

(ii) Unlike the embryo, which is a growing or dividing zygote, the foetus has limbs that resemble humans.

(b)

(i) It is an enzyme.

(ii) The acrosome, located at the top of the sperm’s head, secretes an enzyme that aids sperm

(c)

(i) It is the stage of human embryo development in which a spherical mass of cells is formed.

(ii) The stage after Morula is called a blastocyst.

(d)

(i) Between the amnion and the embryo, amniotic fluid is present.

(ii) The amniotic fluid serves the following purposes:

1. It protects the embryo from physical harm caused by jerks or mechanical shocks.

2. Maintains a constant pressure surrounding the embryo.

3. Allows the foetus to move around in a limited way.

(e)

(i) The villi are two sets of tiny finger-like projections that make up the placenta. The uterine wall produces one pair of villi, while an extension (allantois) from the embryo produces the other.

(ii) The main chemicals that move from the foetus to the mother through the placenta are oxygen and amino acids.

(iii) Progesterone and oestrogen

(f)

(i) Blastocyst

(ii) It happens approximately 5-7 days following ovulation.