Free Embryonic Development MCQs with Answers

1. If the fate of each blastomere is foretold then what will that cleavage be?

• A. Spiral and indeterminate
• B. Radial and determinate
• C. Radial and indeterminate
• D. Spiral and determinate

Explanation: Spiral cleavage means that the planes of cell division are diagonal to the vertical axis of the embryo. Determinate cleavage means that the fate of each embryonic cell is fixed very early. A spiral and determinate cleavage is that in which the lines or planes of cleavage are not symmetrical between poles instead these are diagonal to the polar axis and produce unequal cells around the axis of polarity and all the blastomeres have determined role to play in the formations of embryo. The fate of each blastomere is foretold.

2. In animals, a reproductive system developed from:

• A. Ectoderm
• B. Blastoderm
• C. Mesoderm
• D. Endoderm

Explanation: Mesoderm gives rise to muscular, skeletal, and reproductive systems.

3. In most triploblastic after embryonic development, the three layers are represented as?

• A. Their functions in the body
• B. Structures associated with them
• C. Separate layers of cells
• D. Structures formed from them

Explanation: Triploblasts are organisms whose body is derived from all three germ layers, which are the endoderm, mesoderm and ectoderm.

4. Spiral and determinate cleavage is found in the embryo of:

• A. Frog
• B. Leech
• C. Pigeon
• D. Brittle star

Explanation: Explanation: Spiral cleavage is a type of embryonic development in which cells divide at oblique angles, resulting in a helical arrangement. Determinate cleavage means that the fate of each embryonic cell is determined early in development. This pattern is characteristic of many protostomes, such as leeches.

5. In spermatophytes (seeded plants), the ploidy of embryo and the generation in which the embryo is produced is:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: In sporophytes, the embryo is diploid and produced in sporophyte generation.So option A is correct.

6. One of the changes that would occur in an ovary of flowering plants after double fertilisation is that the

• A. Pollen tube will disappear
• B. Antipodal cells will double in number
• C. Polar nuclei will form triploid endosperm
• D. Egg cell will fuse with synergids to form diploid zygote

Explanation: In flowering plants, double fertilization involves two key events: one sperm cell fuses with the egg cell to form a diploid zygote, and the other sperm cell fuses with the two polar nuclei to form a triploid cell that develops into the endosperm. Therefore, the correct answer is Option C: polar nuclei will form triploid endosperm. The other options describe processes or changes that do not occur in the context of double fertilization or within the ovary following this event.

7. In an experiment, a cell was isolated from an unknown embryo at four-cell stage and allowed to divide. Even after repeated divisions, this isolated cell did not develop into a complete animal.The embryo used in the above experiment could be of a:

• A. Frog
• B. Snail
• C. Starfish
• D. Sparrow

Explanation: The correct answer is starfish. In starfish, the embryo exhibits a mosaic development pattern. This means that the fate of each cell is determined early, and if a cell is isolated, it cannot develop into a complete organism. In contrast, embryos of organisms like frogs, snails, and sparrows have regulative development, where cells have the potential to form a complete organism if separated at an early stage. Therefore, the inability of the isolated cell to form a complete animal suggests that the embryo is from a starfish.

8. The option which characterises apomixis in the flowering plants is

• A. Option A
• B. Option B
• C. Option C
• D. D

Explanation: In apomixis, meiosis is either skipped or modified, and the MMC or other cells within the ovule divide mitotically to produce a diploid embryo sac. Apomixis is a form of asexual reproduction in plants where seeds are formed without fertilization. So option D is correct. All other options give wrong combinations.

9. Following are some of the events that occur during the development of animals.The structures formed during the event X are

• A. Somites
• B. Blastomeres
• C. Epiblast and hypoblast
• D. Neural groove and neurocoel

Explanation: The correct answer is Option B: blastomeres. Blastomeres are the cells that result from the cleavage of the zygote, which is one of the earliest stages of embryonic development. During cleavage, the single-celled zygote divides into multiple smaller cells known as blastomeres.Option A: somites are structures related to later development stages involved in forming vertebra and muscle organization, not the initial cell divisions. Option C: epiblast and hypoblast are layers formed during gastrulation, which occurs after cleavage. Option D: neural groove and neurocoel are structures formed during neurulation, another later stage of development.

10. A 16 weeks pregnant woman, who already has a son with haemophilia, visits a genetic counsellor to know about the genetic health of her second baby.The diagnostic test that the genetic counsellor refers to the woman would be:

• A. Ultrasound
• B. Gene therapy
• C. Tissue culture
• D. Amniocentesis

Explanation: The correct answer is amniocentesis. Amniocentesis is a diagnostic test typically performed between 15 and 20 weeks of pregnancy. It involves taking a small sample of the amniotic fluid surrounding the fetus, which contains fetal cells that can be analyzed for genetic conditions such as haemophilia.Ultrasound is not suitable for detecting genetic conditions; it is used for visualizing the fetus and assessing its development. Gene therapy is a treatment method and not used for diagnosis. Tissue culture is a laboratory technique and not applicable for prenatal genetic testing.