Question

The z scheme of photosynthesis was proposed by:
A.Hill and Bendall
B.Emerson
C.Arnon
D.Rabinowitch and Govindjee

Answer 1

Photosynthesis is typically a conversion of light energy into chemical energy by green plants and other species. Light energy is actually absorbed and used by green plants during photosynthesis to turn water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.

Complete solution:
First, we have to understand each person’s observations and findings. Then we should make sure that whose findings are closer to the z scheme.
Now we can go through each given option,
A) Hill and Bendall- The Z diagram depicts the electron transfer pathway from water to NADP$+$. Plants use this mechanism to convert light energy into electrical energy, which is then converted into chemical energy in the form of reduced NADPH and ATP. The Z scheme was suggested by Hill and Bendall. It includes both the PS I and PS II photosystems.
B) Emerson - The discovery of the photosynthetic unit - that $2400$ chlorophyll molecules can only reduce one molecule of oxygen - was his first major contribution. He also discovered that one molecule of oxygen needs $8$ quanta of light to be reduced, implying that photosynthesis is much less effective than previously assumed. So the z scheme of photosynthesis was not proposed by Emerson.
C) Arnon- Arnon's work on plant micronutrients led him to photosynthesis, where he discovered (and named) photosynthetic phosphorylation (photophosphorylation) in$1954$, a discovery that ranks alongside the discovery of animal respiration. So the z scheme of photosynthesis was not proposed by Arnon.
D) Rabinowitch and Govindjee- Govindjee finished his biophysics PhD with Eugene Rabinowitch. They've made groundbreaking contributions to the field of photosynthesis, concentrating on Photosystem II's role. They didn’t propose the z scheme.
As a result, option A is the correct response. So we can say that the z scheme of photosynthesis was proposed by Hill and Bendall.

Note:
Electrons are taken from water (to the left) and donated to the lower (non excited) oxidised form of ${\text{P680}}$ in the Z Scheme. When a photon is absorbed, ${\text{P680}}$ is excited to${\text{P68}}{{\text{0}}^*}$, which “jumps” to a more actively reducing species. With proton pumping, ${\text{P68}}{{\text{0}}^*}$ donates an electron to the quinone cytochrome bf chain.