From the following set of statements regarding DNA topology, state whether each of the given statement is either True or False.

A.      The two strands of cccDNA can be easily separated without any breakage of bonds.

B.      Circular DNA molecules purified from bacteria and eukaryotes are usually negatively supercoiled.

C.      Interwound writhe and spiral writhe are topologically different.

D.      The organisms that live under extreme temperature conditions have been found to have positively supercoiled DNA.

E.      Negative supercoils can be thought of as a store of free energy that aids in processes that require strand separation.

#Question id: 2532

#Unit 2. Cellular Organization

Nonenzymatic proteins whose exact functions are uncertain. Such proteins may be localized in the walls of specific cell types or more widespread;

cell wall protein                                                                                Tissue localization

A) HRGP (hydroxyprolinerich glycoprotein)                                  i) Xylem, fibers, cortex, root hairs

B) AGP (arabinogalactan protein)                                                  ii) Primary xylem and phloem

C) PRP (proline-rich protein)                                                           iii) Cambium, vascular parenchyma

 D) GRP (glycine-rich protein)                                                          iv) Varied cell-specific expression

Which of the following combination of nonenzymatic protein with its correct location?

#Question id: 2533

#Unit 2. Cellular Organization

Cellulose microfibrils have an ordered structure and are synthesized at the plasma membrane, given characteristics of microfibrils;

a) Each microfibril is composed of an estimated 18 parallel chains of (1,4)-linked β-D-glucose chains tightly bonded to each other to form a crystalline microfibril

b) Microfibrils have hydrophilic surfaces, populated by polar –OH groups extending from theplane of the sugar rings

c) Microfibrils have hydrophobic surfaces, populated by nonpolar C–H groups populating thesides of stacked glucose chains

 d) microfibril important for enzymatic attack by microbial cellulases, which dock onto the hydrophobic surface and remove one glucan chain at a time

Which of the following from given characterstics of microfibrils is incorrect?

#Question id: 2534

#Unit 2. Cellular Organization

How the matrix polysaccharides are differ from the cellulose?

#Question id: 2535

#Unit 2. Cellular Organization

Expansins belong to a large superfamily of proteins, divided into two major expansin families, α-expansins (EXPAs) and β-expansins (EXPBs), what is the function of these two?

a) EXPAs are more active on eudicot cell walls,whereas EXPBs are more active on grass cell walls

b) EXPAs are more active on grass cell walls, whereas EXPBs are more active on eudicot cell walls

c) EXPAs loosen cellulose–cellulose junctions containing xyloglucan, whereas EXPBs loosen wall complexes containing GAX

d) EXPAs loosen wall complexes containing GAX, whereas EXPBs loosen cellulose–cellulose junctions containing xyloglucan

Which combination is correct from some given above functions of expansins,?

#Question id: 2536

#Unit 2. Cellular Organization

If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, then the concentration of H+ ions ________.

#Question id: 2537

#Unit 2. Cellular Organization

Which of the following is the smallest structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope?