Step 1: Read the diagram:
The diagram shows a syringe that withdraws fluid from the amniotic cavity around the foetus.
The fluid is spun in a centrifuge. The fluid part and the cell part separate.
The cells are then grown in a culture dish.
Step 2: Name the procedure (part a):
This procedure is amniocentesis.
A needle is passed through the mother abdomen into the amniotic sac and a little amniotic fluid is drawn out.
The fluid holds cells shed by the foetus. These cells are cultured and their chromosomes and enzymes are studied.
It is a pre-natal diagnostic technique used about the 14th to 16th week of pregnancy.
Step 3: Advantage and disadvantage (part a):
Advantage: it detects genetic and chromosomal disorders early, for example Down syndrome, haemophilia and sickle-cell anaemia.
Disadvantage: it can be misused to find the sex of the foetus, which leads to female foeticide. It also carries a small risk of miscarriage.
Step 4: Saheli (part b):
Saheli is a non-steroidal oral contraceptive pill. Its active compound is centchroman.
Other oral pills contain hormones, mainly progestogens or progestogen-oestrogen combinations. These are steroidal.
Saheli is taken once a week, after a first course of twice a week. Other pills must be taken daily for 21 days.
Because it is non-hormonal, it has very few side effects.
Final Answer:
(a) Amniocentesis. Advantage: early detection of genetic disorders. Disadvantage: misuse for sex determination (female foeticide). (b) Saheli is non-steroidal (centchroman), taken weekly, with few side effects; other pills are hormonal and taken daily.
