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Human Reproduction — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYHuman Reproduction1 Mark
Question
For two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
Assertion: Placenta acts as a major endocrine organ.
Reason: In mammals, fetal components of the placenta derive initially from the chondroblast.
✓

Answer

  1. Assertion is true, but reason is false.

​​​​​​​​​​​​​​​​​​​​​Explanation:

Placenta may be defined as the connection between the fetal membranes (amnion and chorion) and the uterine wall (decidua basal is, the portion of the decidua which is directly adjacent to conceptus at the implantation site) for physiological exchange between the fetus and the mother's blood.

In mammals, the fetal components of the placenta derive initially from trophoblast, connected with embryonic blood stream, through its contact with yolk sac. Placenta also acts as a major endocrine organs as it secretes hormones such as estrogen, progesterone and hCG that are essential for maintaining a maternal physiological condition appropriate for continued development of the conceptus.

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