COMPETITIVE EXAM MCQs SERIES of LIFE SCIENCES for CSIR-UGC NET/JRF, SLET, GATE, and other entrance tests: DEVELOPMENTAL BIOLOGY – Early Development of Plants and Animals.
Syllabus Outline
- Zygote formation, cleavage, blastula formation, embryonic fields, gastrulation and formation of germ layers in animals.
- Embryogenesis.
- Establishment of symmetry in plants.
- Seed formation and germination.
This quiz contains 25 concept-based, most frequently asked MCQs on “DEVELOPMENTAL BIOLOGY – Early Development of Plants and Animals”. Each question has a single correct/most appropriate answer.
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1. The Drosophila egg exhibits a centrolecithal distribution of yolk. Which corresponding cleavage pattern is characteristic of this yolk type?
A) Radial holoblastic cleavage
B) Superficial meroblastic cleavage
C) Discoidal meroblastic cleavage
D) Rotational holoblastic cleavage
2. During the gastrulation of frog embryos, bottle cells initiate a critical movement that creates the dorsal lip of the blastopore. This movement involves the inward folding and migration of a sheet of cells. Identify this specific cell movement.
A) Invagination
B) Ingression
C) Intercalation
D) Involution
3. Which of the following organs is derived entirely from the Mesoderm germ layer?
A) Adrenal Medulla
B) Anterior Pituitary Gland
C) Spleen
D) Thyroid Gland
4. A fish embryo shows cleavage restricted to a thin layer over the yolk. Which egg type and cleavage does this describe?
A) Mesolecithal; Radial holoblastic
B) Telolecithal; Discoidal meroblastic
C) Isolecithal; Rotational holoblastic
D) Centrolecithal; Superficial meroblastic
5. In mammals, which process during the morula stage separates the inner cell mass from the trophoblast?
A) Blastomere polarisation
B) Differential adhesion
C) Wnt/β-catenin gradient formation
D) Cell ingression through the early streak
6. The primary function of the archenteron, formed during gastrulation, is to:
A) Provide a fluid-filled cavity for shock absorption.
B) Establish the ectoderm, mesoderm and endoderm germ layers.
C) Define the definitive gut tube and subsequent digestive organs.
D) Initiate convergent extension movements along the dorsal axis.
7. During the formation of the definitive nervous system in vertebrates, the underlying mesoderm structure required for the induction of the neural plate is the:
A) Intermediate Mesoderm
B) Lateral Plate Mesoderm
C) Splanchnic Mesoderm
D) Notochord
8. An isolated vegetal plate of a sea urchin forms archenteron and mesenchyme autonomously. This shows:
A) Conditional specification
B) Regulative development
C) Autonomous specification
D) Syncytial specification
9. In early chick development, the rudimentary streak is formed along the midline of the epiblast, defining the future axes. Cells migrating through the cranial region of the rudimentary streak will primarily form the:
A) Yolk sac and chorion
B) Definitive endoderm and notochord
C) Neural tube and epidermis
D) Lateral plate mesoderm
10. Which inhibitory molecule is known to restrict Nodal/Activin signalling to the vegetal hemisphere by acting as a maternal factor in the animal hemisphere of vertebrate embryos?
A) Chordin
B) Lefty
C) Noggin
D) Coco
11. The apical-basal axis in the Arabidopsis embryo is established by the directional, cell-to-cell transport of auxin. Which family of membrane proteins is critically responsible for this polar transport mechanism?
A) F-box proteins
B) DELLA proteins
C) PIN proteins
D) CLAVATA receptors
12. During Arabidopsis embryogenesis, the hypophysis is derived from which of the two cells resulting from the initial asymmetric division of the zygote?
A) Apical cell
B) Basal cell
C) Suspensor cell
D) Central cell
13. Which phytohormone is correctly described as the principal morphogen responsible for establishing the apical-basal axis in the early plant embryo?
A) Cytokinin
B) Gibberellin
C) Abscisic Acid
D) Auxin
14. Overexpression of WUSCHEL in the Shoot Apical Meristem causes:
A) Early flowering
B) Loss of apical dominance
C) Meristem termination
D) Overgrown (fasciated) meristem
15. Gibberellin promotes germination by:
A) Inducing Abscisic Acid
B) Stabilising DELLAs
C) Degrading DELLAs
D) Phosphorylating ABI5
16. Which embryonic structure in a chick embryo is functionally analogous to the dorsal lip of the blastopore in a Xenopus embryo, serving as the primary organising centre?
A) Area Pellucida
B) Hensen’s Node
C) Rudimentary Streak
D) Area Opaca
17. Abscisic Acid Insensitive mutants show:
A) Dwarfism
B) Vivipary and desiccation intolerance
C) Ethylene insensitivity
D) Delayed germination
18. Which environmental factor is generally associated with the inactivation/modification of the Delay of Germination protein levels, leading to the termination of seed primary dormancy?
A) High Salinity Stress
B) Stratification
C) Lack of Light
D) Precocious germination
19. In the Abscisic acid signalling pathway, what is the regulatory outcome of the binding of Abscisic acid to the PYR/PYL/RCAR receptors?
A) Degradation of the ABI transcription factors via the 26S proteasome.
B) Inhibition of PP2C protein phosphatases, allowing SnRK2 kinases to phosphorylate targets.
C) Activation of DELLA proteins, promoting their translocation to the nucleus.
D) Induction of GA synthesis genes, restoring the ABA/GA balance.
20. Auxin, Jasmonic acid, and Ethylene are known to modulate seed dormancy. They achieve this primarily by:
A) Increasing Gibberellic acid levels, overriding Abscisic Acid effects.
B) Modulating the Abscisic acid pathway by influencing the expression of Abscisic acid signalling components.
C) Acting as potent antagonists of RGL2, inducing its proteasomal degradation.
D) Regulating the transcriptional activity of WUSCHEL.
21. The phenomenon of seed after-ripening involves a gradual loss of dormancy. Mechanistically, after-ripening is primarily associated with:
A) Increase in Abscisic acid synthesis.
B) Increased sensitivity to environmental temperature signals.
C) Modification or inactivation of dormancy-promoting factors.
D) Transcriptional induction of ABI3 and ABI5.
22. Assertion (A): Polar auxin transport, mediated by PIN proteins, is critical for establishing the apical-basal axis and bilateral symmetry during Arabidopsis embryogenesis.
Reason (R): Mutations in the GNOM gene, which is required for PIN protein cycling and localisation, lead to radialized embryos lacking both root and cotyledons.
A) Both A and R are true, and R is the correct explanation of A.
B) Both A and R are true, but R is NOT the correct explanation of A.
C) A is true, but R is false.
D) A is false, but R is true.
23. Assertion (A): The loss of maternal Vg1 in zebrafish embryos closely phenocopies the loss of zygotic Nodal, resulting in severe defects in mesendoderm formation.
Reason (R): Nodal is required for Vg1 secretion and processing, and conversely, Nodal’s endogenous activity requires maternal Vg1, indicating the necessity of a Vg1-Nodal heterodimer for induction.
A) Both A and R are true, and R is the correct explanation of A.
B) Both A and R are true, but R is NOT the correct explanation of A.
C) A is true, but R is false.
D) A is false, but R is true.
24. Assertion (A): In Arabidopsis, the DELLA protein RGL2 promotes seed dormancy by repressing GA signalling.
Reason (R): RGL2 is necessary to sustain the expression of ABA signalling components (like ABI5 and ABI3) and the de novo synthesis of ABA in dormant seeds upon imbibition.
A) Both A and R are true, and R is the correct explanation of A.
B) Both A and R are true, but R is NOT the correct explanation of A.
C) A is true, but R is false.
D) A is false, but R is true.
25. Assertion (A): During gastrulation in Xenopus, the blastocoel is displaced and eventually filled by the migrating mesoderm and endoderm.
Reason (R): The archenteron forms concurrently and gradually replaces the space previously occupied by the blastocoel, serving as the precursor of the definitive gut cavity.
A) Both A and R are true, and R is the correct explanation of A.
B) Both A and R are true, but R is NOT the correct explanation of A.
C) A is true, but R is false.
D) A is false, but R is true.
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References
- Michael Barresi and Scott Gilbert (2023). Developmental Biology, Oxford University Press, 13th Edition.
- Lincoln Taiz, Ian Max Møller, Angus Murphy, and Eduardo Zeiger (2022). Plant Physiology and Development, Oxford University Press, 7th Edition.
- Geoffrey Cooper and Kenneth Adams (2022). The Cell: A Molecular Approach, Oxford University Press, 9th Edition.
- Alberts, B., Johnson, A., Lewis, J., Morgan, D., Raff, M., Roberts, K., & Walter, P. (2014). Molecular Biology of the Cell, Garland Science, 4th Edition.
- Robert A Weinberg, Robert A. Weinberg (2006). The Biology of Cancer, Taylor & Francis, 1st Edition.
- Gupta, P.K. (2022). Cell and Molecular Biology, Rastogi Publications, 5th Edition.
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