Free Embryonic Development MCQs with Answers
46 Embryonic Development MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Embryonic development begins after fertilization with cleavage and formation of the morula and blastula, followed by gastrulation and the establishment of germ layers. It includes organ formation, tissue differentiation and early growth, rather than the later increase in size associated with postnatal development.
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46 questions · page 5 of 5
41. Embryonic mass can generate all of the following except:
- A. Amnion
- B. Chorion
- C. Yolk sac
- D. Allantois
Explanation: The embryonic mass is the mass of cells inside the embryo that will eventually give rise to the definitive structures of the fetus. It cannot generate the chorion, which forms the placenta.
Correct answer: Chorion42. Trophoblast cells begin to display _ selection adhesion molecules on their surface soon after the blastocyst hatching.
- A. X selection
- B. D selection
- C. L selection
- D. C selection
Explanation: Trophoblast cells begin to display adhesion molecules on their surface soon after the blastocyst hatching.
Correct answer: L selection43. The foertal sex becomes apparant during the:
- A. First trimester
- B. Second trimester
- C. Third trimester
- D. Both A and B
Explanation: During pregnancy, the fetal sex becomes apparent during the second trimester, which is around the 13th to 16th week of pregnancy. This is when ultrasound scans can often reveal whether the baby is a boy or a girl.
Correct answer: Second trimester44. The primitive streak first appears in which labeled stage of embryonic diagram?
- A. A
- B. B
- C. C
- D. D
Explanation: The primitive streak is a key structure that forms during early embryonic development and marks the beginning of gastrulation. Stage C in the diagram represents the point where the inner cell mass begins to differentiate and form the bilaminar disc, which is when the primitive streak first appears as a groove in the epiblast layer.
Correct answer: C45. Which of the following structures is formed from ectodermal tissue:
- A. Brain
- B. Muscles
- C. Skeleton
- D. Bones
Explanation: The brain is formed from ectodermal tissue. During embryonic development, the ectoderm is one of the primary germ layers that gives rise to various structures including the nervous system, skin, hair, and nails. The brain and nervous system originate from specialized ectodermal tissue. Therefore, option a is correct.
Correct answer: Brain46. All animals begin life as a _.
- A. Multicellular fertilised egg
- B. Single fertilised egg
- C. Hollow blastula
- D. Gastrula
Explanation: All animals, from simple sponges to complex humans, begin their lives as a single fertilized egg cell, also known as a zygote. This zygote is formed when a sperm fertilizes an egg cell, resulting in a single cell with a unique combination of genetic material from both parents.From this single cell, the embryo develops through various stages, including:1. Cleavage: The zygote divides into multiple cells.2. Blastula: A hollow ball of cells forms.3. Gastrula: The blastula undergoes invagination, forming a multilayered embryo.So, while all animals do pass through the blastula and gastrula stages, they all begin life as a single fertilized egg.
Correct answer: Single fertilised egg