Skip to content
Login Register

#ethylene

23 public questions tagged with this topic.

CHEMISTRY

How many sigma bonds are present in the C₂H₄ molecule?

C₂H₄ has a double bond (1 sigma, 1 pi) between carbons and 4 single bonds (4 sigma) to hydrogens. Total sigma bonds = 1 + 4 = 5. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

View Details
Transgenic Plant -2

Ethylene synthesis pathway involves which intermediate?

Ethylene synthesis pathway involves ACC as obligate intermediate bridging methionine metabolism and hormonal action. Methionine sulfur is conserved via Yang cycle, while ethylene formation proceeds via S-adenosylmethionine intermediate SAM, then ACC. ACC, chemically 1-aminocyclopropane-1-carboxylic acid, is a strained cyclic nonprotein amino acid accumulating transiently in cytosol and vacuole. It is synthesized in cytosol, can be conjugated to N-malonyl-ACC by ACC N-malonyltransferase for vacuolar storage or to γ-glutamyl-ACC, or transported long distance from flooded roots to shoots via xyle

Ref: Buchanan Biochemistry Molecular Biology Plants Ch 17 ACC pathway; PMID 11536542 Ethylene biosynthesis.

View Details
Transgenic Plant -2

ACC synthase catalyzes conversion of SAM to:

Plant ethylene biosynthesis, termed Yang cycle, converts sulfur amino acid methionine to gaseous hormone ethylene through two committed enzymatic steps plus recycling. Methionine is first activated by SAM synthetase encoded by MAT genes using ATP to form S-adenosylmethionine, universal methyl donor and precursor for polyamines and ethylene. The rate-limiting step is catalyzed by ACC synthase, a pyridoxal 5'-phosphate dependent aminotransferase encoded by multigene family ACS1-ACS12 differentially regulated by auxin, cytokinin, wounding, flooding and fruit ripening cues. ACS cleaves SAM into 1-

Ref: Taiz & Zeiger Plant Physiology 6th ed Ch 22 Ethylene; Yang Cycle review Annu Rev Plant Physiol 1984.

View Details
Plant tissue culture 1

Ethylene differs from other plant hormones because it is:

Ethylene stands unique among classical phytohormones being only gaseous hydrocarbon C2H4 with high diffusivity without need for active transport proteins. Biosynthesis follows methionine to S-adenosyl methionine AdoMet then ACC via ACC synthase ACS multigene family rate limiting, finally oxidation to ethylene by ACC oxidase ACO requiring iron ascorbate oxygen. As volatile it accumulates in sealed culture vessels influencing morphogenesis unless vented. Signaling occurs at endoplasmic reticulum membrane where receptors ETR1, ERS1, ETR2 function as negative regulators; in absence of ethylene the

Ref: Bleecker & Kende Annu Rev Cell Dev Biol 2000 ethylene; NCBI NBK21448 ethylene.

View Details
Cell Signaling Other Signaling Pathways

Ethylene signaling in plants uses

two-component system, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

View Details
Phytohormone ALL PYQS

Ethylene triple response includes all except:

Go with D — Increased elongation. Under Phytohormone ALL, this is the standard explanation you’d use in class: it names the real driver or definition, while the rest are nearby but wrong. Not these: A) Reduced elongation; B) Radial swelling; C) Tight apical hook. When two options sound similar, choose the one that matches the textbook definition most tightly.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

View Details