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Pregnancy and Development

Pregnancy is the period during which the embryo develops in the uterus after implantation, supported by the placenta and the mother's body.

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Student-friendly explanation

After fertilisation, the zygote divides to form an embryo. The embryo implants in the uterine lining. The placenta helps exchange nutrients, oxygen, and wastes between mother and developing baby without mixing their blood directly. In humans, the gestation period is about nine months.

How to write this in exams

  1. 1

    Start with the exact idea

    Pregnancy is the period during which the embryo develops in the uterus after implantation, supported by the placenta and the mother's body.

  2. 2

    Then show how to use it

    Write the sequence: fertilisation in oviduct, zygote division, movement to uterus, implantation, placenta formation, development.

  3. 3

    Add one concrete example

    The placenta supplies nutrients and oxygen to the developing embryo and helps remove wastes from it.

  4. 4

    Avoid this incomplete answer

    Writing that implantation occurs in the ovary is wrong because implantation occurs in the uterine lining.

Definition

Pregnancy is the period during which the embryo develops in the uterus after implantation, supported by the placenta and the mother's body.

Example

The placenta supplies nutrients and oxygen to the developing embryo and helps remove wastes from it.

Rule to remember

Fertilisation forms zygote; zygote divides into embryo; embryo implants in uterus; placenta supports exchange.

Memory hook

Implant in uterus; exchange through placenta.

Examples and method

Worked example

If a question asks why the uterus has a thick lining, explain that it supports implantation and nourishment of the developing embryo.

Method to apply

Write the sequence: fertilisation in oviduct, zygote division, movement to uterus, implantation, placenta formation, development.

Diagram support

A simple flow diagram can show zygote, embryo, implantation, placenta, and foetus development.

How CBSE asks it

Questions ask the role of placenta, meaning of implantation, and basic sequence from fertilisation to development.

Avoid common mistakes

Common confusion

Students often write that the placenta is the baby’s stomach; it is an exchange organ between mother and developing baby.

Common wrong answer

Writing that implantation occurs in the ovary is wrong because implantation occurs in the uterine lining.

Exam tip

For placenta questions, mention nutrients, oxygen, waste removal, and connection through the umbilical cord.

Quick check

What is implantation in human reproduction?

Implantation is the attachment of the early embryo to the lining of the uterus, where further development can take place.

Answer writing and exam use

1-mark answer

Pregnancy is the period during which the embryo develops in the uterus after implantation, supported by the placenta and the mother's body.

2-mark answer

Pregnancy is the period during which the embryo develops in the uterus after implantation, supported by the placenta and the mother's body. Fertilisation forms zygote; zygote divides into embryo; embryo implants in uterus; placenta supports exchange. The placenta supplies nutrients and oxygen to the developing embryo and helps remove wastes from it.

3-mark answer

After fertilisation, the zygote divides to form an embryo. The embryo implants in the uterine lining. The placenta helps exchange nutrients, oxygen, and wastes between mother and developing baby without mixing their blood directly. In humans, the gestation period is about nine months. Fertilisation forms zygote; zygote divides into embryo; embryo implants in uterus; placenta supports exchange. If a question asks why the uterus has a thick lining, explain that it supports implantation and nourishment of the developing embryo. Questions ask the role of placenta, meaning of implantation, and basic sequence from fertilisation to development. Writing that implantation occurs in the ovary is wrong because implantation occurs in the uterine lining.
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