Tag: living world of plants - plant physiology

Engelman discovered the action spectrum of photosynthesis in 1833. He found that bacteria accumulated in the region of blue and red light of split spectrum. He thus discovered the effect of the different wavelength of the light on photosynthesis and at that time he discovered the first action spectrum of photosynthesis.
So, the correct option is B.

The process of photophosphorylation was discovered by Arnon. He used the term assimilatory to refer ATP and $NADP$. Photophosphorylation is the process in which light energy is converted into chemical energy through the production of ATP. The process of reduction of $NADP$ into $NADP + H^{+}$ may be denoted as electron transport system (ETS). 

Peter Dennis Mitchell, was a British biochemist who was awarded the 1978 Nobel Prize for Chemistry for his discovery of the chemiosmotic mechanism of ATP synthesis. 

A) Photosynthesis was partially discovered by Jan Baptista van Helmont, a Belgian chemist, physiologist and physician.
B) Stephen Hales proved that plants require light for photosynthesis.
C) Joseph Priestley revealed the essential role of air in the growth of green plants.
So the correct answer is 'Stephen Hales'.

a. Peter Mitchell, in 1961 proposed chemiosmotic hypothesis, according to this hypothesis, the ATP is synthesized by ATPase complexes located on the non-appressed portions of thylakoid membranes, particularly towards margins.

b. Free energy is a concept useful in the thermodynamics of chemical or thermal processes in engineering and science proposed by Gibbs.

c. Daniel L. Arnon in 1961 discovered photophosphorylation, It is the process of phosphate group transfer into ADP to synthesize energy-rich ATP molecule making use of light as an external energy source.

d. CO$ _2$ fixation in dark reaction was thoroughly worked out by M. Calvin.

Hence, the correct answer is 'a-s, b-r, c-q, d-p'.

Julius Robert Mayer made his claim in his The Organic Motion in its Relation to Metabolism which was published in 1845. In this publication, he wrote: "The plants take in one form of power, light and produce another power, chemical difference." He used the term ‘power’ for energy and ‘chemical difference’ for chemical energy. He, therefore, made it clear that plants do not only produce organic matter but also provide the energy which sustains life. Consequently, his finding has made further enlightenment on photosynthesis.

Julius Robert von Mayer was a German physician and physicist. He was the first to state the law of the conservation of energy i.e., energy is neither created nor destroyed. He stated that the sun is the ultimate source of energy for both plants and animals and that when absorbed plants convert this light energy through the process of photosynthesis.

Photosynthesis is a process by which green plants manufacture their food with the help of carbon dioxide and water in the presence of sunlight. When light energy is absorbed by photosynthetic pigment chlorophyll, then it gets exited and photosynthetic reaction center loses an electron. In this way, light energy is converted to chemical energy. Conversion of light energy into chemical energy is the primary event in photosynthesis. R. Mayer stated that in photosynthesis light energy is converted into chemical energy. He also proposed that the sun is the ultimate source of energy utilized by living organisms.