COMPETITIVE EXAM MCQs SERIES of LIFE SCIENCES for CSIR-UGC NET/JRF, SLET, GATE, and other entrance tests: DEVELOPMENTAL BIOLOGY – Morphogenesis and Organogenesis in Animals.
Syllabus Outline
- Cell aggregation and differentiation in Dictyostelium.
- Axes and pattern formation in Drosophila, amphibia and chick.
- Organogenesis – vulva formation in Caenorhabditis elegans, eye lens induction, limb development and regeneration in vertebrates.
- Differentiation of neurons, post-embryonic development- larval formation, metamorphosis
- Environmental regulation of normal development.
- Sex determination.
This quiz contains 25 concept-based, most frequently asked MCQs on “DEVELOPMENTAL BIOLOGY – Morphogenesis and Organogenesis in Animals”. Each question has a single correct/most appropriate answer.
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1. The Quiescent Centre acts as a signalling centre in the Root Apical Meristem. Which of the following molecular events is essential for the specification and maintenance of the Quiescent Centre and the surrounding initials?
A) High levels of Cytokinin signalling promote cell differentiation and the transition zone.
B) The unidirectional transport of the PIN1 protein towards the root tip, establishing an auxin minimum.
C) The non-autonomous movement of the short root transcription factor from the stele into the Quiescent Centre
D) The autonomous action of the WUSCHEL-Related WOX5 protein is synthesised and acts within the Quiescent Centre cells.
2. Which of the following statements concerning the interaction of Auxin and Cytokinin in Arabidopsis root development is generally correct?
A) Auxin promotes cell differentiation, while cytokinin promotes cell division in the proximal meristem.
B) Auxin inhibits cytokinin biosynthesis via downregulation of specific IPT genes.
C) The mutant, defective in cytokinin signalling, shows an enlarged root meristem due to excessive cell division.
D) Cytokinin exclusively controls the fate of the vascular cylinder, independent of auxin signalling.
3. The Arabidopsis primary root is longitudinally organised into four developmental zones: the proximal meristem, transition zone, elongation zone, and differentiation zone. Which hormone is primarily responsible for maintaining the size of the proximal meristem by promoting cell division?
A) Cytokinin, by upregulating PIN genes.
B) Ethylene suppresses cell differentiation.
C) Auxin, by maintaining the Quiescent Centre niche and promoting cell proliferation.
D) Gibberellin promotes cell elongation in the transition zone.
4. In the tunica and corpus organisation of the shoot apical meristem, which statement accurately describes the division patterns?
A) Tunica layers undergo periclinal divisions, while the corpus undergoes anticlinal divisions
B) Tunica layers undergo anticlinal divisions, while the corpus undergoes divisions in multiple planes
C) Both tunica and corpus undergo only anticlinal divisions
D) Tunica undergoes radial divisions while corpus undergoes tangential divisions
5. The quiescent centre in the root apical meristem is characterised by:
A) Rapid cell division provides cells to all root tissues
B) Cells undergoing anticlinal divisions to increase root diameter
C) Differentiated cells that have lost meristematic potential
D) Cells with low mitotic activity that maintain stem cell identity in surrounding initials
6. The CLAVATA-WUSCHEL negative feedback loop regulates:
A) Root hair initiation and elongation
B) Stem cell population size in the shoot apical meristem
C) Lateral root emergence through the cortex
D) Guard cell differentiation in epidermis
7. The closed meristem organisation, as seen in many monocots, differs from the open meristem by:
A) Having no distinct corpus region
B) Lacking a tunica-corpus boundary with meristematic initials separated from stem tissues
C) Possessing stem cell initials that do not contribute to stem tissues directly
D) Having only one tunica layer instead of two
8. During lateral root development in Arabidopsis, founder cells originate from:
A) Pericycle cells adjacent to xylem poles
B) Endodermal cells opposite phloem poles
C) Cortical cells in the elongation zone
D) Quiescent centre cells that migrate laterally
9. In the ABC model of flower development, class A genes alone specify:
A) Carpels in the fourth whorl
B) Sepals in the first whorl
C) Petals in the second whorl
D) Stamens in the third whorl
10. Which statement correctly describes the difference between determinate and indeterminate inflorescences?
A) Determinate inflorescences have a persistently active apical meristem
B) Indeterminate inflorescences terminate in a flower, stopping further growth
C) Determinate inflorescences convert the apical meristem to a floral meristem
D) Indeterminate inflorescences produce flowers simultaneously
11. The “quartet model” extends the ABC model by proposing that:
A) Four whorls of organs require four classes of genes
B) Floral organ identity is specified by tetrameric protein complexes
C) Each floral organ undergoes four developmental stages
D) Four different hormones regulate flower development sequentially
12. The proximal-distal axis of leaf development in Arabidopsis is influenced by:
A) Uniform distribution of auxin throughout the primordium
B) Pressed flower expression in lateral domains
C) Differential expression of genes at boundaries
D) Abscisic acid gradients from tip to base
13. During root development, the transition zone between the meristem and elongation zone is characterised by:
A) Maximum rate of cell division
B) Cells begin to elongate while division declines
C) Complete cell differentiation with secondary wall deposition
D) Formation of the Casparian strip in all cell layers
14. In floral organ identity determination, what would be the predicted phenotype of an Arabidopsis plant with only class A and class B genes functional?
A) Sepals-petals-petals-sepals
B) Sepals-sepals-carpels-carpels
C) Sepals-petals-stamens-carpels
D) Leaves-sepals-petals-petals
15. In the root apical meristem, the distal stem cell niche is maintained primarily by:
A) WUSCHEL expression in the quiescent centre
B) Auxin signalling and PLETHORA transcription factors
C) Cytokinin antagonises auxin responses
D) Ethylene promotes cell differentiation
16. The cymose inflorescence structure seen in some plant species results from:
A) Conversion of the terminal meristem into a flower, with growth continuing from axillary meristems
B) Continuous activity of the inflorescence meristem producing lateral flowers
C) Suppression of terminal flower activity
D) Constitutive expression of the flowering locus in all meristems
17. Which experimental observation would provide the strongest evidence that a gene is required for floral meristem identity?
A) Mutant flowers earlier than wild-type plants
B) Mutants produce inflorescences that continue vegetative development instead of forming flowers
C) Mutants show altered phyllotaxy in vegetative shoots
D) Mutants have an increased number of floral organs per flower
18. The adaxial identity in leaf primordia is associated with:
A) Development of abaxial leaf surface characteristics
B) Suppression of all cell division in the primordium
C) Lateral margin outgrowth exclusively
D) Formation of vascular bundles and adaxial leaf surface traits
19. The radial symmetry of Arabidopsis flowers is maintained because:
A) Cycloidea orthologs are uniformly expressed throughout the flower
B) There is low expression of genes conferring dorsoventral asymmetry
C) All floral organs develop at identical rates
D) Class ABC genes are expressed asymmetrically across the flower
20. The regulation of root meristem size by Auxin and Cytokinin involves a complex homeostatic feedback loop. Evaluate the following statements:
I – Cytokinin application promotes cell differentiation, reducing the size of the proximal meristem
II – Auxin treatment increases meristem size by promoting cell division in the proximal meristem
III – The interaction is characterised by a feedback loop where Cytokinin can modulate Auxin transport, and Auxin can repress Cytokinin biosynthesis.
IV – The IAA3/SHY2 repressor is a direct target of cytokinin signalling, linking the two pathways in root growth control.
A) I and II only
B) II, III, and IV only
C) I, II, III, and IV
D) I, II and III only
21. Consider the following statements about root apical meristem organisation:
I – The quiescent centre is located at the apex of the root
II – Columella initials give rise to the root cap
III – Cortex/endodermis initials produce both cortex and endodermis
IV – The epidermis/lateral root cap initial divides periclinally
A) I, II and III
B) I, II, III and IV
C) I and IV
D) II, III and IV
22. The following statements concern auxin’s role in plant development:
I – Auxin maxima at the Shoot Apical Meristem periphery mark sites of leaf primordium initiation
II – Polar auxin transport is mediated by PIN proteins
III – Auxin inhibits root apical meristem activity
IV – Auxin promotes cambial cell division
A) I, II and IV
B) I and II only
C) II, III and IV
D) I, III and IV
23. Assertion (A): The maintenance of the stem cell population in the shoot apical meristem of Arabidopsis is achieved through a precise balance between cell proliferation and differentiation signals.
Reason (R): The CLAVATA pathway acts as a crucial negative regulator that limits the expression domain of WUSCHEL to prevent overproliferation.
A) Both A and R are true, and R is the correct explanation for A.
B) Both A and R are true, but R is NOT the correct explanation for A.
C) A is true, but R is false.
D) A is false, but R is true.
24. Assertion (A): The root apical meristem is established early, at the globular stage of embryogenesis, following an asymmetric cell division of the hypophysis.
Reason (R): This early asymmetric cell division is crucial for determining the proximal-distal axis and establishing the Quiescent Centre.
A) Both A and R are true, and R is the correct explanation for A.
B) Both A and R are true, but R is NOT the correct explanation for A.
C) A is true, but R is false.
D) A is false, but R is true.
25. Assertion (A): The L1 layer of the shoot apical meristem gives rise exclusively to the epidermis.
Reason (R): Cells in the L1 layer undergo only anticlinal divisions, maintaining the single cell layer.
A) Both A and R are true, and R correctly explains A
B) Both A and R are true, but R does not correctly explain A
C) A is true, but the R is false
D) Both A and R are false
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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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