15.9.1 Gamete Formation (Structured Question 1 & 2)

Question 1:
(a) Diagram 1 shows part of a female reproductive system.
The development of zygote occurs in this system.

Diagram 1

Based on the Diagram 1, describe the development of the zygote after fertilization until implantation. [4 marks]


(b) Diagram 2 shows a method to overcome infertility in a married woman with a blockage in both of her Fallopian tubes.

Diagram 2

Explain how this method helps this woman to have a baby. [4 marks]


(c) Diagram 3 shows the schematic diagram of spermatogenesis and oogenesis in human.


Explain how this method helps this woman to have a baby. [10 marks]


Solution:

(a)

After fertilization:

• The zygote begins to divide repeatedly by mitosis and travels along the Fallopian tube towards the uterus.
• It forms a two-celled embryo.
• Further division results in the formation of a ball of cells or morula.
• Next, the morula becomes a blastocyst, a hollow ball of cells.
• Implantation of the blastocyst then occurs in the endometrium.

(b)

It is the in vitro fertilization (IVF) method.

• A fine laparoscopy is used to remove a mature ovum from the ovary.
• The ovum is then placed in a Petri dish with a culture solution to mature.
• Then, concentrated sperms from the father are added.
• A sperm and the ovum fuse to form a zygote which develops into an embryo.
• After 2 – 4 days, when the embryo reaches the eight-cell stage, it is inserted into the uterus through the cervix.
• For implantation in the uterine wall.
• The baby conceived is called a test tube baby.

(c)

Similarities:

• Both processes occur in the reproductive organs.
• Both processes involve the process of meiosis.
• Both processes produce haploid gametes that are involved in fertilization.