Sample Qs- development of Zygote

Diagram shows the development of a human zygote.
(a) Describe the processes from P to Q .[ 4 marks ]

(b) Pregnant women are advised not to smoke and avoid from drugs and alcohol.
Explain the above statement in terms of the development of foetus. [6m]
c)The fallopian tubes of a married woman are blocked, making it impossible for her to conceive through the natural process. She and her husband insist to have their own child . Explain one modern technique that can be used by the childless couple
to conceive. Justify your choice. [10M]

Sample answer:
Able to describe process 1 to 5 based on diagram.
P1 – Ovulation releases a secondary oocyte , which enters the oviduct.
P2 - The secondary oocyte starts meiosis II which progresses until metaphase II.
P3 - The nuclei of a sperm cell (n) and the ovum (n) fuse and form a diploid zygote (2n). // A sperm fertilize the ovum to form a zygote.
P4 - Zygote begins to divide repeatedly by mitosis as it travels along the fallopian tube towards the uterus.
P5 - Morula is form followed by blastula.
P6 - Implantation occur / The blastocyst attaches itself to the endometrium.
Any 4 points

Able to explain why Pregnant woman are advised not to smoke and avoid from drugs and alcohol.
Sample Answer :
P1 Cigarette contain nicotine / DDT / lead particles.
P2 - The wall of maternal blood capillaries and the wall of foetal blood capillaries are semi-permeable.
P3 - Nicotine, drugs and alcohol are small in sizes.
P4 - Nicotine, drugs and alcohol can diffuse from maternal blood capillaries to foetal blood capillaries /
P5 through the placenta
P6 The substances carried by umbilical vein to the foetus.
P7- Nicotine, drugs or alcohol can effect the development of foetus
P8 (example) cause disable / miscarriage . birth defect/ illness in the resulting baby. Any 6 points

Able to explain the technique
Sample Answer:
P1 : Modern technique that can be used :
The couple can use the in-vitro fertilization (IVF) method.
P2 : mother undergoes hormonal treatment to produce more secondary oocycte
P3 : In this method a fine laparoscope is used to remove the secondary oocyte from her ovary.
P4 : The secondary oocyte are placed in a Petri dish of culture solution .
P5 : Then ( concentrated ) sperms from the husband are added to the secondary oocyte.
P6 : The sperms and ova fuse and develop into embryos/zygote // fertilization occurred to form zygote
P7 : After two to four days when the embryos have reached the eight-cell stage
P8 : they are inserted into the uterus through the cervix
P9 : for implantation on the uterine wall.
P10 : If the procedure is successful, the embryos develop to foetus.
P11 : Babies conceived this way are sometimes called test-tube babies.