Respiration in Plants Test - 28

Substrate level phosphorylation means when energy from breakdown of glucose is directly released as ATP or GTP. In Krebs cycle, only in one step GTP is released i.e., during the conversion of succinyl CoA to succinic acid. In all the other steps, energy is released as either NADH or FADH. Thus, the correct answer is option C.

• The citric acid cycle is also known as the TCA cycle (tricarboxylic acid cycle) or the Krebs cycle. 
• It is a series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins, into adenosine triphosphate (ATP) and carbon dioxide.
•  In eukaryotic cells, the citric acid cycle occurs in the matrix of the mitochondrion.
•  In prokaryotic cells, such as bacteria, which lack mitochondria, the citric acid cycle reaction sequence is performed in the cytosol. 
• Hence, Mitochondria is the site for the Krebs cycle.
• So, the correct answer is 'Krebs cycle'.

The overall mechanism of cellular respiration involves four subdivisions: glycolysis, in which glucose molecules are broken down to form pyruvic acid molecules; the Krebs cycle, in which pyruvic acid is further broken down and the energy in its molecule is used to form high-energy compounds such as NADH; the electron transport system, in which electrons are transported along a series of co-enzymes and cytochromes and the energy in the electrons is released; and chemiosmosis, in which the energy given off by electrons is used to pump protons across a membrane and provide the energy for ATP synthesis. Thus, option A is correct.

The respiratory quotient (or RQ or respiratory coefficient), is a dimensionless number used in calculations of basal metabolic rate (BMR), when estimated from carbon dioxide production.
RQ = CO$$_{2}$$ eliminated / O$$_{2}$$ consumed. Thus, option A is incorrect. Photosynthetic coefficient is the specific light spectrum at which chlorophyll absorbs light. Thus, option B is wrong. Photosynthetic yield is the quantity of the end product of the photosynthesis. Thus, option C is wrong. The temperature coefficient (Q$$_{10}$$) represents the factor by which the rate (R) of a reaction increases for every 10-degree rise in the temperature (T). The rate (R) may represent any measure of the progress of a process. Thus option D is correct.

Fermentation is a metabolic process in which an organism converts a carbohydrate, such as starch or a sugar, into an alcohol or an acid. For example, yeast performs fermentation to obtain energy by converting sugar into alcohol. Bacteria perform fermentation, converting carbohydrates into lactic acid.
$$C_6H_{12}O_6$$ (glucose) ------>2 $$C_2H_5OH$$ (ethanol) + 2 $$CO_2$$ (carbon dioxide).
The substrate for the fermentation is any carbohydrate (glucose) and the end products are such as acids or alcohols and $$CO_2$$. 

The pyruvic acid enters Krebs cycle in form of acetyl CoA where it is oxidatively decarboxylated into CO$$_2$$. The complete Kreb cycle leads to the net formation of 2 molecules of ATP by substrate-level phosphorylation, 8 molecules of NADH plus 2 molecules of FADH$$_2$$ (via succinate dehydrogenase). The NADH and FADH$$_2$$ then enter the ETS to drive ATP production by substrate level phosphorylation. 

The quantum requirements of the individual light reactions of photosynthesis are defined as the number of light photons absorbed for the transfer of one electron. The quantum requirement for each light reaction has been found to be approximately one photon. The total number of quanta required, therefore, to transfer the four electrons that result in the formation of one molecule of oxygen via the two light reactions should be eight. 
The quantum yield of a process in which molecules give up their excitation energy (or "decay") is the fraction of excited molecules that decay via that pathway.
The Emerson effect is the increase in the rate of photosynthesis after exposure to light of wavelength 670 nm far red light and 700 nm, red light respectively. When simultaneously exposed to light of both wavelengths, the rate of photosynthesis is far higher than the sum of the red light and far red light photosynthesis rates. 
Red drop effect is the photosynthetic efficiency of monochromatic light is greatly reduced above 680 nm, even though chlorophyll absorbs well up to 700 nm. 

Correct Option: B

Explanation for the correct option:

•  Glycolysis converts glucose into two 3-carbon molecules called pyruvate. 
• The energy released during glycolysis is used to make ATP. 
• Enolase is used to convert 2-phosphoglycerate (2PG) to phosphoenolpyruvate (PEP) in the 9th reaction of glycolysis. 
• It is a reversible dehydration reaction.