A  plant species arrives at  an  island  for the first time, where it  is  exposed to  a  new set of  pollinators.  Over the course of 20 generations, the characteristics of its flowers change. The figures above show the frequency distribution of petal length in the original colonizing population (Figure 1) and 20 generations later (Figure 2). Which of these explanations is consistent with the observed change in petal length?

#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

#Question id: 10472

#Unit 6. System Physiology – Plant

In greenhouse grown leaves of broad bean stomatal movements closely correlate with incident solar radiation at the leaf surface and stomatal aperture  opening and closing as light levels reaching the leaf surface given in graph

A. Mid of the day stomatal aperture has a largest diameter, water loss and transpiration rate will be highest at the  same time

B. In mid of the day incident light is highest in terms of PPFD and can also say CO2 diffusion will be highest

C. The stomatal aperture has a largest diameter resulting closing of stomatal pore, water loss and transpiration rate will be lowest due to closing of stomata

D. In mid of the day incident light is highest in terms of PPFD resulting CO2 will not diffuse

which of the following combination from the given graph will be CORRECT?

#Question id: 10471

#Unit 6. System Physiology – Plant

Under temperate conditions, which one of the two major factors that are involved with light-dependent stomatal opening are,