4.9.1 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.





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