#Question id: 2528
#Unit 2. Cellular Organization
Cell walls of prokaryotes, fungi, algae, and plants differ from each other in chemical composition and molecular structure, yet they all serve three common functions:
a) regulating cell volume
b) determining cell shape
c) mechanically protecting the delicate protoplast against biochemical and physical assaults
d) used to make synthetic fibers
Which of the following common functions is correct?
#Question id: 2529
#Unit 2. Cellular Organization
Cell walls commonly are classified into two major types. This classification is based not on structural or biochemical differences;
A) primary walls and
B) secondary walls
i) walls formed during cell growth
ii) walls that are formed after cell enlargement stops
iii) multilayered walls that are strengthened and waterproofed by lignin
iv) Usually they are thin and simple, but some times may be thick and multilayered, such as those found in collenchyma or in the epidermis
v) highly specialized in structure and composition, reflecting the differentiated state of the cell
Which of the following is the correctly represents features of primary and secondary walls?
#Question id: 2530
#Unit 2. Cellular Organization
A thin layer called the middle lamella is found at the interface, middle lamella is typically enriched with acidic polysaccharides_____A______, which may be complexed with_______B__________.
#Question id: 2531
#Unit 2. Cellular Organization
The specific linkages between sugar rings, including the specific carbons that are linked together and the configuration of the linkage, are important for the properties of the polysaccharide;
I) Amylose a)β(1,3)-linkages
II) Cellulose b) β (1,4)-linkages
III) Callose c) α(1,4)-linked
d) α (1,3)-linkages
Which of the following linkage combination is correct linkages of the polysaccharides?
#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?