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

Which of the following statements is/are false?

a. After triple fusion, the central cell becomes the primary endosperm cell and develops into an embryo. b. Both syngamy and triple fusion take place in an embryo sac. c. Embryo develops at the micropylar end of the embryo sac where the zygote is situated.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

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

This is the correct option as this statement is false. After triple fusion, the central cell becomes the primary endosperm cell and develops into the endosperm.

Multiple choice

The time in a goose's life when it imprints the image of its mother is called

  1. embryonic

  2. critical period

  3. crucial stage

  4. impressionable stage
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The critical period is a specific developmental window when young animals form strong attachments to moving objects, typically their mother. Konrad Lorenz's famous goose experiments demonstrated that this imprinting occurs during a limited time frame and is irreversible. Missing this critical period can permanently impair the ability to form normal social bonds.

Multiple choice

Allantois consists of ___________.

  1. mesoderm inside and ectoderm outside

  2. mesoderm outside and ectoderm inside

  3. mesoderm inside and endoderm outside

  4. mesoderm outside and endoderm inside

  5. ectoderm outside and endoderm inside
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Allantois consists of mesoderm on outside and endoderm internally.

Multiple choice

What is a vitelline membrane?

  1. Tertiary egg membrane

  2. Secondary egg membrane

  3. Primary egg membrane

  4. All of these

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It is formed around the plasma membrane of egg secerted by ovum itself.

Multiple choice

Which of the following explains tunica serotina correctly?

  1. It is a part of decidua that lines uterus at a place other than the site of attachment of embryo.

  2. It lies between embryo and lumen of uterus.

  3. It is a part of decidua underlying chronic villi and overlying myometrium.

  4. It is the uterine wall of uterus during pregnancy.

  5. It is decidua reflexa.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Tunica serotina also known as Basal deciduas or Decidua basalis is a part of deciduas underlying chorionic villi and overlying myometrium.

Multiple choice

Germinal disc differentiate into two layers. Which of the options names it correctly?

  1. Outer epiblast of larger columnar cells and inner hypoblast of smaller cuboidal cells.

  2. Outer epiblast of larger cuboidal cells and inner hypoblast of smaller columnar cells.

  3. Outer epiblast of smaller cuboidal cells and inner hypoblast of larger columnar cells.

  4. Outer epiblast of smaller columnar cells and inner hypoblast of larger cuboidal cells.

  5. Outer hypoblast and inner epiblast.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cells of inner cell mass or embryonal knob get rearranged to form a flat embryonic disc or germinal disc. The latter differentiate into two layers, outer epiblast of large columnar cells and inner hypoblast of smaller cuboidal cells.

Multiple choice

Which is the source of all the germ layers in the embryo?

  1. The hypoblast

  2. The epiblast

  3. Both hypoblast and epiblast

  4. Osteoblast

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

The first epiblast cell moves inward and displaces the hypoblast to create endoderm. Once endoderm is formed, inwardly moving epiblast forms mesoderm. Cells remaining in the epiblast form ectoderm. Thus, the epiblast is source of all germ layers.

Multiple choice

Ootid is formed as a result of

  1. meiosis-II

  2. meiosis-I

  3. mitosis

  4. amitosis

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Secondary oocyte undergoes meiosis-II to form ootid.