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.

Topic in NCERT: Oxidative phosphorylation

Line in NCERT: "it is for this reason that the process is called oxidative phosphorylation."

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.

Topic in NCERT: Respiratory quotient

Line in NCERT: "when fats are used in respiration, the rq is less than 1."

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

Topic in NCERT: Glycolysis

Line in NCERT: "the initial stage of cellular respiration takes place in the cytoplasm. each glucose molecule is broken through a series of enzyme catalysed reactions into two molecules of pyruvic acid. this process is called glycolysis."

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

Topic in NCERT: Amphibolic pathway

Line in NCERT: "glucose is the favoured substrate for respiration."

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

Topic in NCERT: Fermentation

Line in NCERT: "in fermentation, say by yeast, the incomplete oxidation of glucose is achieved under anaerobic conditions by sets of reactions where pyruvic acid is converted to co2 and ethanol."

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

Topic in NCERT: Respiratory quotient

Line in NCERT: "when fats are used in respiration, the rq is less than 1."

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

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

Topic in NCERT: Electron transport system (ets) and oxidative phosphorylation

Line in NCERT: "the following steps in the respiratory process are to release and utilise the energy stored in nadh+h* and fadh2. this is accomplished when they are oxidised through the electron transport system and the electrons are passed on to o2 resulting in the formation of h2o."

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

Topic in NCERT: Tricarboxylic acid cycle

Line in NCERT: "the summary equation for this phase of respiration may be written as follows: nadh+h nad* coa pyruvate (3c) -nad* nadh+h co2 acetyl coenzyme a (2c) oxaloacetic acid (4c) citric acid (6c) co2 nad* nadh+h α-ketoglutaric acid malic acid (4c) citric acid cycle fadh2 fad* cer (5c) co2 nad nadh+h succinic acid (4c) gdp gtp citric acid cycle"

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

Topic in NCERT: Respiration in plants

Line in NCERT: "o2 is the ultimate acceptor of electrons and it gets reduced to water."

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

Topic in NCERT: Aerobic respiration

Line in NCERT: "hence, there can be a net gain of 38 atp molecules during aerobic respiration of one molecule of glucose."

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.

Topic in NCERT: Oxidative phosphorylation

Line in NCERT: "this is called oxidative phosphorylation. in this process o2 is the ultimate acceptor of electrons and it gets reduced to water."

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.

Topic in NCERT: Cellular respiration

Line in NCERT: "c6h12o6 + 6o2 → 6co2 + 6h2o + energy"

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

Topic in NCERT: Cellular respiration and metabolism

Line in NCERT: "pyruvate, which is formed by the glycolytic catabolism of carbohydrates in the cytosol, after it enters mitochondrial matrix undergoes oxidative decarboxylation by a complex set of reactions catalysed by pyruvic dehydrogenase."

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

Topic in NCERT: Aerobic respiration

Line in NCERT: "hence, there can be a net gain of 38 atp molecules during aerobic respiration of one molecule of glucose."

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.

Topic in NCERT: Respiratory quotient

Line in NCERT: "the ratio of the volume of co2 evolved to the volume of o2 consumed in respiration is called the respiratory quotient (rq) or respiratory ratio."

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

Topic in NCERT: Respiration in plants

Line in NCERT: "pyruvic acid is then the key product of glycolysis."

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.

Topic in NCERT: Metabolism of pyruvic acid

Line in NCERT: "metabolism of two molecules of pyruvic acid (produced from one glucose molecule during glycolysis)."

Respiratory Quotient 

Topic in NCERT: Respiratory quotient

Line in NCERT: "the ratio of the volume of co2 evolved to the volume of o2 consumed in respiration is called the respiratory quotient (rq) or respiratory ratio."