#components

Sea urchin -lll

Respiratory burst involves:

Following fertilization calcium transient, sea urchin eggs increase oxygen consumption several-fold within minutes, termed respiratory burst. Calcium activates NADPH-dependent oxidase complex in cortex producing superoxide converted to hydrogen peroxide. Hydrogen peroxide serves as substrate for ovoperoxidase released from cortical granules to catalyze di-tyrosine cross-links hardening fertilization envelope. Burst is calcium dependent, inhibited by calcium chelators BAPTA, and occurs concurrently with envelope elevation and cortical reaction. It parallels NADPH oxidase activity in phagocytes

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Respiratory burst calcium dependent oxygen increase fertilization.

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Ecosystem - Structure Components Stratification

Which of the following is an example of an abiotic component of an ecosystem?

Abiotic components include non-living elements such as soil, water, temperature, and sunlight.

Ref: NCERT Class 12 Biology Chapter 12: Ecosystem Ecosystem - Structure Components Stratification

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DNA Structure Double Helix and Packaging - Nucleosome

Which of the following is NOT a component of a nucleosome?

A nucleosome consists of DNA wrapped around histone proteins with linker DNA in between, but RNA polymerase is not part of it.

Ref: NCERT Class 12 Biology Chapter 5: Molecular Basis of Inheritance DNA Structure Double Helix and Packaging - Nucleosome

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Nucleic Acids - DNA RNA Structure and Functions

Which of the following components is found in DNA but NOT in RNA?

DNA contains thymine, whereas RNA contains uracil instead of thymine.

Ref: NCERT Class 11 Biology Chapter 9: Biomolecules Nucleic Acids - DNA RNA Structure and Functions

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Microscopy

Which component is absent in confocal microscopy imaging?

Modern confocal systems use point illumination from lasers, scanning mirrors, dichroic filters, pinhole apertures for spatial filtering and sensitive point detectors such as photomultiplier tubes or hybrid GaAsP detectors. Image formation relies on sequential photon counting rather than widefield capture by an area array chip. Therefore a conventional charge-coupled device camera, typical of widefield epifluorescence, is not employed for primary imaging in laser-scanning confocal instruments. Spinning-disk confocals may use EMCCD, but classical laser-scanning architecture reconstructs images f

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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