Placenta
- CBSE · NCERT Class 10, Ch 7 How do Organisms Reproduce?
- ICSE Class 10, Unit 3 Human Anatomy and Physiology
The placenta is a disc-shaped organ in the uterus wall that links the baby to the mother, passing food and oxygen in and wastes out.
After fertilisation, the embryo settles in the lining of the uterus. This is called implantation. The lining has thickened and has a rich blood supply. The placenta forms here, and the umbilical cord joins it to the baby. Its finger-like villi sit in pools of the mother's blood. The two bloods come very close but do not mix.
- Nutrition: glucose passes from mother to baby.
- Respiration: oxygen passes in, and carbon dioxide passes out.
- Excretion: wastes pass out to the mother's blood.
- Hormones: the placenta makes hormones that keep the pregnancy going.
Amniotic fluid is something else. It fills the sac round the baby and cushions it. It does not feed the baby.
A small example
A mother eats a meal, and glucose from it enters her blood. At the placenta it passes into the baby's blood. The umbilical cord carries it to the baby. Carbon dioxide goes the other way.
Where marks go
In CBSE, Question 12 of the 2026-27 Science sample paper asks, for 2 marks, what changes in the uterus after implantation. The board's Science marking scheme for 2026-27 gives two points. The lining thickens with a rich blood supply. A placental link forms with the embryo. The scheme prints no split, so an answer with one change leaves the other out.
In ICSE, the 2025 Biology paper asked for two functions of amniotic fluid. In CISCE's report on the 2025 Biology paper, examiners name "nutrient supply" as a wrong answer and say candidates confused amniotic fluid with the placenta. The 2027 specimen paper matches parts to jobs on a diagram. Its draft marking scheme gives the placenta one job: letting glucose pass from the mother's blood into the baby's.
Sources
Facts last checked against these sources on 30 September 2026.
- Science, Class X (2026-27), Chapter 7: How do Organisms Reproduce? · NCERT
- Science (086) Marking Scheme, Class X 2026-27 - Question 12 · CBSE Academic Unit
- Science (086) Sample Question Paper, Class X 2026-27 - Question 12 · CBSE Academic Unit
- ICSE Biology syllabus, Examination Year 2028 (January 2026) - Class X, Unit 3 · CISCE
- ICSE Analysis of Pupil Performance: Biology (October 2025) - Question 7(iii) · CISCE
- ICSE 2027 Specimen Question Paper and Draft Marking Scheme: Biology - Question 2(v) · CISCE
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