Biology Questions and Answers – Human Reproduction – Pregnancy and Embryonic Development – 2

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This set of Biology MCQs focuses on “Human Reproduction – Pregnancy and Embryonic Development – 2”.

1. Which organ is the first to form in the developing human fetus, formed after just 1 month of pregnancy?
a) Heart
b) Brain
c) Kidney
d) Liver
View Answer

Answer: a
Explanation: The heart is the first organ to form in the developing fetus. It is formed after one month of pregnancy. The brain takes more time to develop.
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2. External genital organs are developed during _________
a) first month of pregnancy
b) first trimester
c) second trimester
d) third trimester
View Answer

Answer: b
Explanation: Limbs and digits, along with external genitalia, are formed during the first trimester. This is a period of 12 weeks after pregnancy.

3. Fetal movements can be observed during ____________
a) first month of pregnancy
b) first trimester
c) second trimester
d) third trimester
View Answer

Answer: c
Explanation: Trimesters are periods of three months’ post-pregnancy. Fetal movements can be observed starting five months’ post-pregnancy i.e., during the second trimester.
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4. Which of these is not an associated function of the increased maternal hormones estrogen, progesterone, prolactin, and cortisol?
a) Development of fetus
b) Metabolic changes in the mother
c) Maintenance of pregnancy
d) Lactation
View Answer

Answer: d
Explanation: The maternal increase in the hormones is responsible for the development and growth of the fetus, maintenance of pregnancy, and the changes in metabolism in mother essential for the proper nourishment of fetus. Lactation is not a part of pregnancy. It occurs after the baby has been delivered.

5. Implantation is followed by the differentiation of inner cell mass into outer _______ and inner ______
a) ectoderm, endoderm
b) ectoderm, mesoderm
c) ectoderm, mesendoderm
d) mesoderm, endoderm
View Answer

Answer: a
Explanation: The process of implantation is followed by the rapid differentiation of the inner mass of cells of the blastocyst. These cells differentiate into the outer layer of ectoderm and the inner layer of endoderm. Mesoderm arises later.
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6. What layer separates ectoderm from the endoderm in the developing fetus?
a) Mesenchyme
b) Mesendoderm
c) Mesoderm
d) Placenta
View Answer

Answer: c
Explanation: Ectoderm and endoderm are the first layers that arise as a result of the differentiation of the implanted blastocyst. Eventually, a third layer separating ectoderm from the endoderm arises. This layer is called mesoderm.

7. The ability of a cell to differentiate is called ______
a) potential
b) potency
c) stemness
d) development
View Answer

Answer: b
Explanation: Development is the process that leads to the formation of an organism from the zygote. Potency is the ability of a cell to differentiate into another cell type. Stemness is the potential of a cell to divide indefinitely and also differentiate to multiple different cell types.
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8. The cells within the inner cell mass that possess the ability to give rise to the entire organism are called _______
a) placental cells
b) stem cells
c) mother cells
d) zygote
View Answer

Answer: b
Explanation: The stem cells are a population of cells within the inner cell mass that possess the ability to give rise to an entire organism. They have a property called stemness, which gives them this ability.

9. Heart is derived from ______
a) Mesoderm
b) Endoderm
c) Ectoderm
d) Mesenchyme
View Answer

Answer: a
Explanation: Heart is the first organ to develop in the fetus. It is derived from the mesodermal cells. After gastrulation, this differentiates into mesothelium, endothelium, and myocardium.
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