When the temperature of a solution of DNA is raised to near the boiling point of water, the optical density, (called absorbance) at 260 nm markedly increases, a phenomenon known as hyperchromicity. Which of the following properties gets changed due to subsequent denaturation of the DNA molecule?

TLS Online TPP Program

#Question id: 14900

#Unit 6. System Physiology – Plant

polymer-trapping model explains symplastic loading in plants, This model states that the sucrose diffussion takes place through cell to cell via plasmodesmata; which of the following prediction about the diffusion mechanism is INCORRECT?    

TLS Online TPP Program

#Question id: 14901

#Unit 6. System Physiology – Plant

cell walls are essential and are important features of plant cells that perform a number of essential functions. Which of the following are not the characteristics of a cell wall?

TLS Online TPP Program

#Question id: 14902

#Unit 6. System Physiology – Plant

Transpirational water flow in the xylem requires a mechanically strong wall that resists from,

TLS Online TPP Program

#Question id: 14903

#Unit 6. System Physiology – Plant

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?

TLS Online TPP Program

#Question id: 14904

#Unit 6. System Physiology – Plant

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 sometimes 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 correctly represents features of primary and secondary walls?

TLS Online TPP Program

#Question id: 14905

#Unit 6. System Physiology – Plant

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__________.