ATARI for zone-I is located at: - Solved MCQ | Agrigyan

Robert Emerson's photosynthetic experiments:
When Robert Emerson illuminated Chlorella with monochromatic light of wavelength greater than 680 nm (far-red region), he observed a sharp, precipitous decline in quantum efficiency/yield of photosynthesis. This phenomenon is termed the Red Drop (A).
This observation was part of the pioneering discoveries known collectively as the Emerson effect (B), which proved that photosynthesis requires two distinct photosystems (PS-I and PS-II) working in series.
When far-red light was supplemented simultaneously with shorter red light ($\lt 680\text{ nm}$), quantum yield exceeded the sum of the individual yields; this synergistic increase is called the Emerson Enhancement effect (C), not the reduction.

Blackman's classification of cellular respiration based on substrates:
Floating Respiration: Respiration in which hydrolysable storage carbohydrates (sugars, starch) or fats are utilized as respiratory substrates. This is the normal, healthy, primary phase of cellular respiration and does not produce toxic nitrogenous byproducts.
Protoplasmic Respiration: Occurs only when carbohydrate reserves are completely exhausted (starvation or senescence). Protoplasmic proteins are degraded and utilized as substrate, liberating ammonia and toxic amines, eventually causing cellular death.

Thermodynamics and biochemistry of the Krebs Cycle (Citric Acid Cycle / TCA Cycle):
Oxidation: Acetyl-CoA is progressively oxidized to carbon dioxide (\(\text{CO}_2\)). In the process, high-energy electrons are transferred to electron carriers (reducing \(\text{NAD}^+\) to \(\text{NADH} + \text{H}^+\) and \(\text{FAD}\) to \(\text{FADH}_2\)).
Exothermic (Exergonic): The catabolic oxidation of carbon bonds is thermodynamically spontaneous and releases energy (negative \(\Delta G^\circ'\)), a portion of which is conserved by substrate-level phosphorylation (GTP/ATP) while the remaining energy is dissipated as heat.