This set of Class 12 Biology Chapter 3 Multiple Choice Questions & Answers (MCQs) focuses on “Pregnancy and Embryonic Development – 1”.
1. What are the finger-like projections of trophoblast called?
a) Endometrium
b) Placenta
c) Chorionic villi
d) Fetus
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Explanation: The trophoblast of the blastocyst sends finger-like projections into the uterine cell wall to derive nutrition. These projections are called chorionic villi.
2. Chorionic villi and uterine tissue fuse to form ________
a) Zygote
b) Blastula
c) Placenta
d) Endometrium
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Explanation: Trophoblasts project chorionic villi into the endometrium to derive nutrition from the uterine wall. The uterine tissue, in turn, surrounds it along with the blood vessels. These two tissues interdigitate to form the placenta.
3. What tissue is derived from two different organisms?
a) Placenta
b) Endometrium
c) Zygote
d) Gamete
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Explanation: Placenta is a tissue that provides nutrition to the developing fetus. It is derived from two different organisms; the mother and the developing fetus. A zygote is also developed from two organisms i.e., male and female, who have undergone coitus. However, a zygote is a single-cell and not a tissue.
4. Which of the following is not the function of a placenta?
a) Supply of nutrients to the fetus
b) Removal of excretory products from the fetus
c) Supply of carbon dioxide to the fetus
d) Supply of oxygen to the fetus
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Explanation: Placenta connects the maternal system to the fetal system. It provides nutrients for the fetus. It also removes the excretory products that would be harmful to it. It also provides a gaseous exchange by providing oxygen and removing carbon dioxide.
5. What connects the placenta to the embryo?
a) Trophoblast
b) Umbilical cord
c) Chorionic villi
d) Endometrium
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Explanation: Placenta provides nutrition and a medium for the removal of wastes for the fetus. This occurs via the umbilical cord, which connects the fetus to the placenta. The cord remains attached even after the birth and needs to be removed surgically.
6. Which of the following hormone is not produced by the placenta?
a) Relaxin
b) Estrogen
c) Progesterone
d) hPL
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Explanation: Placenta is also an endocrine gland. It provides various hormones like hCG (Human Chorionic Gonadotrophin), hPL (Human Placental Lactogen), Estrogen, and Progesterone. Relaxin is not a placental hormone. It is released from the ovary.
7. Apart from providing a medium for the exchange of nutrients, excretory products, and gases, the placenta is also an exocrine gland.
a) True
b) False
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Explanation: Exocrine glands are glands with ducts that pour their secretions via a duct. Endocrine glands directly release their secretions into the bloodstream or onto a tissue. In this sense, the placenta is an endocrine gland as it lacks ducts.
8. Which hormone is produced by ovary only during pregnancy?
a) Progesterone
b) Chorionic gonadotrophin
c) Relaxin
d) Placental lactogen
View Answer
Explanation: hCG, hPL, and relaxin are released only during pregnancy. hCG and hPL are released by the placenta. The ovary releases relaxin.
9. A scientist was looking at using different hormones in the blood as a marker for pregnancy. Which of the following hormones will not be ideal for this?
a) Progesterone
b) Chorionic gonadotrophin
c) Relaxin
d) Placental lactogen
View Answer
Explanation: To use hormone as a detector for pregnancy, the hormone should be released only during pregnancy. Such hormones are hPL, hCG, and relaxin. Progesterone is not specific to pregnancy and hence cannot serve the purpose.
Sanfoundry Global Education & Learning Series – Biology – Class 12.
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