Tadpoles must undergo a major metamorphosis to become frogs. This change includes reabsorption of the tail, growth of limbs, calcification of the skeleton, increase in rhodopsin in the eye, development of lungs, change in hemoglobin structure, and reformation of the gut from the long gut of an herbivore to the short gut of a carnivore. Amazingly, all of these changes are induced by thyroxine. What is the most likely explanation for such a wide array of effects of thyroxine?

#Question id: 10382

#Unit 6. System Physiology – Plant

Ureides are

#Question id: 10383

#Unit 6. System Physiology – Plant

The nitrogenase enzyme complex fixes N2 produces ammonia, The nitrogenase enzyme complex catalyzes this reaction by following characteristics given below;

a) It can be separated into two components—the Fe protein and the MoFe protein— neither of which has catalytic activity by itself

b) Fe protein is the smaller of the two components and has two identical subunits, each contains an iron–sulfur cluster, which participates in the redox reactions

c) The Fe protein is irreversibly inactivated by O2 while MoFe protein is activated by O2

d) MoFe protein has four subunits, each subunit has two Mo–Fe–S clusters

e) Ferredoxin serves as an electron donor to the Fe protein, and Fe protein reduces the MoFe protein without any hydrolysing ATP

f) Only prokaryotes have nitrogenase enzyme

Which of the following characteristics of nitrogenase enzyme complex is incorrect?

#Question id: 10384

#Unit 6. System Physiology – Plant

Nitrogenase enzyme complex catalyzes the molecular nitrogen fixation, this enzyme not only fixes nitrogen but also perform other reactions given below. Which one is not performed by nitrogenase?

#Question id: 10385

#Unit 6. System Physiology – Plant

The leaves of many species are able to bend toward the sun during its progress across the sky, a phenomenon known as

#Question id: 10386

#Unit 6. System Physiology – Plant

 During light-regulated plant development many seeds require light to germinate, a process called

#Question id: 10387

#Unit 6. System Physiology – Plant