Biology

Embryonic Development

621 Questions

Embryonic development questions cover the biological processes of gamete fusion, germ layer formation, and fetal maturation. The focus lies in identifying extraembryonic structures, trophoblast functions, and sequential developmental stages. This specialized topic appears regularly in biology screening tests and medical entrance examinations.

Germ layer formationBlastocyst implantationExtraembryonic structuresFetal development stagesReproductive physiology

Embryonic Development Questions

Multiple choice

The correct sequence of events of embryogenesis in humans is

  1. fertilisation – zygote – cleavage – morula – blastula – gastrula

  2. fertilisation – cleavage – morula – zygote – blastula – gastrula

  3. fertilisation – zygote – blastula – morula – cleavage – gastrula

  4. cleavage – zygote – fertilisation – morula – blastula – gastrula
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct sequence of events after fertilisation.

Multiple choice

The mesenchyme arising beneath the germinal epithelium is the origin of which analogous cell types?

  1. Leydig and thecal cells

  2. Spermatogonia and oogonia

  3. Sertoli and granulosa cells

  4. Sex cords

  5. Umbilical cord
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mesenchyme arising beneath the germinal epithelium in the testes is the precursor to testicular interstitial cells or Leydig cells while in the ovaries, it is the precursor to ovarian stroma or thecal cells.

Multiple choice

What part of the embryo is the origin of the primordial germ cells?

  1. Gonadal ridge

  2. Endoderm of the yolk sack

  3. Coelomic epithelium

  4. Extraembryonic mesoderm

  5. Genital tubercle
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In gonadal development, undifferentiated primordial germ cells arise from the endoderm lining the yolk sac. These germ cells detach and migrate dorsally to reach the coelomic epithelium lining the genital ridges.

Multiple choice

In a pregnant female, which of the following develops into the placenta?

  1. A trophectoderm

  2. Inner cell mass of the blastocyst

  3. Decidua

  4. Myoblast cells

  5. Myometrium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The developing embryo has two main populations of cells: an inner cell mass and a trophectoderm. The trophectoderm cells lie at the outer surface of the developing embryo and will become the placenta.

Multiple choice

Collenchyma mainly forms _____.

  1. hypodermis

  2. epidermis

  3. endodermis

  4. dermis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Collenchyma is a supporting tissue in plants that is often found in the hypodermis of stems and leaves, providing structural support while allowing for growth.

Multiple choice

Yolk sac placenta is derived from

  1. yolk sac and allantois

  2. yolk sac and chorion

  3. yolk sac and amnion

  4. yolk sac only

  5. -
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chorion is the outermost of the two fetal membranes (the amnion is the innermost) that surround the embryo. The chorion develops villi. Yolk sac placenta develops both from yolk sac and chorion.

Multiple choice

The primitive type of placenta in mammals is referred to as

  1. epitheliochorial placenta

  2. syndesmochorial placenta

  3. endotheliochorial placenta

  4. haemoendothelial placenta

  5. -
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hippopotamuses and pigs have an epitheliochorial placenta. Here a layer of fetal tissue is merely pressed close against the uterus wall.

Multiple choice

Syndesmochorial placenta lacks

  1. chorionic epithelium

  2. uterine connective tissue

  3. chorionic and allantoic membrane

  4. uterine epithelium

  5. -
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is absent in syndesmochorial, epitheliochorial and endotheliochorial type of placenta.