32 Years NEET Previous Year Questions: Respiration in Plants - 2 - NEET MCQ

Oxidative phosphorylation is the synthesis of energy rich ATP from ADP and  inorganic phosphate, that is connected to oxidation of reduced coenzymes produced in cellular  respiration.

Respiratory quotient (R.Q.) is defined as the ratio of the molecules of carbon dioxide given out to the number of oxygen molecules taken in during respiration. Its value for fatty acids is always less than unity.

During aerobic oxidation of pyruvic acid, first of all there is activation of pyruvic acid in which NAD and coenzyme react with pyruvic acid and oxidative decarboxylation takes place leading to the formation of acetyl Co-A. In this process, Lipoic acid amide (LAA), thyamine pyrophosphate (TPP) and NAD are essential to perform this reaction.

Glycolysis is the first step of respiration which occurs without requirement of O₂ and is common to both aerobic and anaerobic modes of respiration.

Firstly, amylose and glycogen are converted to glucose. Deamination of ketogenic amino acids occur and these enter respiratory catabolism as intermediates.

End products of fermentation are ethyl alcohol, lactic acid and CO₂.

Fats are used as respiratory substrates by a number of organisms because they contain more energy as compared to carbohydrates.

In Anaerobic respiration, oxygen is not used in the breakdown of respiratory substrate.

Complete degradation of a molecule of glucose yields 38 ATP molecules.

The two molecules of pyruvate are completely degraded in Krebs cycle to form two molecules of ATP, 8 NADH₂, 2 FADH₂, CO₂ and water.

Terminal cytochorome is cyt a₃. cyt a₃ posseses two copper centers. It helps in transfer of electrons to oxygen.

Respirometer is an instrument for measuring respiratory quotient as well as rate of respiration.

Historically it was believed that 38 ATP is produced from 38 ADP. But the current estimate is that about 30 molecules of ATP are formed when glucose is completely oxidised to CO₂

Oxidative phosphorylation is the synthesis of energy rich ATP molecules with the help of energy liberated during  oxidation of reduced co-enzymes produced in respiration.

The optimum temperature of photosynthesis is 10º–25ºC for C₃ plants and 30º–45ºC for C₄ plants

Aerobic respiration is an enzymatically controlled release of energy in a stepwise catabolic process of complete oxidation of organic substrate into CO₂ and H₂O with O₂ acting as terminal oxidant.

In glycolysis 2ATP are produced at substrate level and NADP produce 6ATP by ETS and 30ATP in mitochondria so there are only two ATP produced in cytoplasm.

The end product of glycolysis is pyruvate. It enters mitochondria and is oxidatively decarboxylated to acetyl CoA before entering into Krebs cycle.

The net gain of energy is equal to 8 ATP in EMP pathway.

Ratio of the volume of CO₂ produced to the volume of O₂ consumed in respiration over a period of time is known as respiratory quotient.

The end product of glycolysis is pyruvic acid which is a three carbon compound.

Glycolysis involves the process of partial oxidation of glucose or similar hexose sugar into two molecules of pyruvic acid through a series of ten enzyme mediated reactions. It occurs in cytoplasm.

Complete degradation of a molecule of glucose produces 12 molecules of NADPH₂ by HMP (hexose monophosphate).

Respiratory Quotient