Evolutionary biology extends and amplifies the explanation of biological phenomena. It complements studies of the proximate causes (immediate, mechanical causes) of biological phenomena If we ask what causes a male bird to sing, the proximate causes include the action of testosterone or other hormones

#Question id: 10488

#Unit 6. System Physiology – Plant

Blue light activates a proton pump at the guard cell plasma membrane. The relationship between proton pumping at the guard cell plasma membrane and stomatal opening is evident from the observations that;

 a.) Orthovandate inhibits the fusicoccin-stimulated opening

 b.) fusicoccin stimulates both proton extrusion from guard cell protoplasts and stomatal opening

 c.) CCCP inhibits the fusicoccin-stimulated opening

 d.) CCCP, a proton ionophore that makes the plasma membrane highly permeable to protons resulting stomatal opening

 Which one of the following observation from the above statements should  be correct?

#Question id: 10487

#Unit 6. System Physiology – Plant

During the patch clamp experiments measure outward electric current in picoamps, pA at the plasma membrane of a guard cell protoplast stimulated by two points A and B showing in the graph.

What is A and B

#Question id: 10486

#Unit 6. System Physiology – Plant

A patch clamp study shows a guard cell protoplast treated in the dark with the fungal toxin fusicoccin which is a well-characterized,

#Question id: 10485

#Unit 6. System Physiology – Plant

What is the role of blue light in terms of stomatal study?

a.) Blue light activates a proton-pumping ATPase in the guard cell plasma membrane and leading to stomatal opening

b.) blue-light stimulation lowers the pH of the apoplastic space surrounding the guard cells, and generates the driving force needed for ion uptake and stomatal opening

c.) The sensitivity of guard cells to blue light increases as a function of their zeaxanthin concentration

d.) npq1 mutant opens at higher fluence rates of blue light, whereas the phot1/phot2 mutant fails to show any blue light–stimulated opening

Which one of the following combination is correct?

#Question id: 10483

#Unit 6. System Physiology – Plant

Given below some facts regarding the stomal responses in light condition. Which one of the following would be INCORRECT?

#Question id: 10482

#Unit 6. System Physiology – Plant

A herbicides dichlorophenyldimethylurea (DCMU) is known as diuron an inhibitor of photosynthetic electron transport. Which one of the following option would be correct about diuron?

a.) Blocks electron flow at the plastoquinone acceptors of PSII by competing for the binding site of plastoquinone

b.) causes a partial inhibition of stomatal closing

c.) accepts electrons from the early acceptors of PSI such as A0 and then reacts with oxygen to form superoxide, O2 –

d.) causes a partial inhibition of light-stimulated stomatal opening