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Right answer is (B) C-C BONDS

To explain: The breaking of the C-C bonds of complex compounds through oxidation within the cells, leads to the release of a CONSIDERABLE AMOUNT of energy. This process is known as respiration.

The CORRECT choice is (B) Two

The explanation: Complex IV REFERS to cytochrome c oxidase complex containing cytochromes a and a3, and two copper centres. The ELECTRONS in ETS pass from one carrier to another VIA complex I to IV.

The correct option is (b) Glycolysis

The best explanation: In any case, all living ORGANISMS retain the ENZYMATIC machinery to partially oxidise glucose WITHOUT the help of OXYGEN. This breakdown of glucose to pyruvic acid is CALLED glycolysis.

Correct choice is (a) O2

The EXPLANATION is: PLANTS do not require CO2, N2 or water vapour for RESPIRATION. Like human beings, plants also require OXYGEN for respiration so that they can release CO2. It is through photosynthesis, that they require carbon dioxide and release oxygen in a very large AMOUNT.

The correct answer is (C) Breakdown of food MATERIALS to RELEASE energy

For explanation: CELLULAR respiration is the mechanism of breakdown of food materials within the cell to release energy and the trapping of this energy for the SYNTHESIS of ATP.

Right OPTION is (b) False

For EXPLANATION I would say: Fermentation accounts for only a partial breakdown of glucose whereas in aerobic RESPIRATION it is completely degraded to CO2 and H2O.

The correct answer is (a) Respiratory Quotient

The explanation is: RQ STANDS for Respiratory Quotient. It is the RATIO of the VOLUME of CO2 evolved to the volume of O2 consumed in RESPIRATION. It is also known as the respiratory ratio.

The CORRECT choice is (d) 38 ATP

The best I can EXPLAIN: Aerobic respiration involves the complete oxidation of GLUCOSE. There can be a net gain of 38 ATP molecules during aerobic respiration of ONE molecule of glucose.

Correct CHOICE is (a) Peripheral protein

Easiest explanation: The F1 HEADPIECE that is present in the Complex V is a peripheral membrane protein complex and contains the site for synthesis of ATP from ADP and inorganic phosphate.

The correct option is (d) Oxygen

The best I can explain: Oxygen ACTS as the final hydrogen acceptor. Oxygen is present in the matrix of the MITOCHONDRIA and finally accepts the protons and forms water molecules. Oxygen is the MOLECULE which drives the whole process of oxidative phosphorylation.

Correct option is (b) TWO

For explanation I would say: The energy released during the electron transport system is utilised in synthesising ATP with the HELP of ATP synthase-Complex V. This complex CONSISTS of two MAJOR components F1 and F0.

Correct ANSWER is (d) Coenzyme A

Best EXPLANATION: The reaction catalysed by pyruvic dehydrogenase requires the participation of SEVERAL coenzymes that INCLUDE NAD^+ and Coenzyme A.

Right answer is (b) False

The BEST I can explain: In lactic acid fermentation as well as ALCOHOLIC fermentation, the REDUCING agent is NADH+H^+ which is re-oxidised to NAD^+. Both these processes are HAZARDOUS, as either acid or ALCOHOL is produced.

Right option is (d) STOMATA

The best I can EXPLAIN: Plants, unlike animals, have no specialised ORGANS for GASEOUS exchange but they use stomata and lenticels for this purpose. Plants can easily get along without any specialised respiratory organs.

Right option is (a) To release and utilise energy

For explanation: The steps in the respiratory process in the ETS are to release and utilise the energy STORED in NADH + H^+ and FADH2. This system is present in the inner mitochondrial membrane.

Correct answer is (d) REGENERATION of malic acid

Easiest explanation: The points which are necessary for the TCA CYCLE to RUN CONTINUOUSLY are:

i. CONTINUED replenishment of Oxaloacetic acid

ii. Regeneration of NAD^+ from NADH

iii. Regeneration of FAD^+ from FADH2

Correct CHOICE is (b) Possible only theoretically

The best explanation: YES, it is possible to make calculations of the net GAIN of the ATP that is FORMED in the respiratory pathway by the oxidation of some suitable respiratory substrates but this can remain only a theoretical exercise as the real amount of energy released in the cell may VARY.

The correct option is (C) Slow

Easy EXPLANATION: NADH is oxidised to NAD^+ rather slowly in fermentation, however, the reaction is very vigorous in the CASE of AEROBIC respiration. The reducing AGENT in fermentation is NADH + H^+.

Correct option is (c) Glucose

To ELABORATE: Glucose is the favoured substrate for respiration because glucose is a carbohydrate and is readily available in the cells through the food that cell intakes. It also RELEASES a LARGE amount of energy on its OXIDATION.

The correct option is (d) THREE

Easy explanation: The COMPLETE oxidation of pyruvate by the stepwise REMOVAL of all the hydrogen atoms takes PLACE while leaving three molecules of Carbon-dioxide.

Right choice is (c) Three

To elaborate: There are three major ways in which DIFFERENT cells handle pyruvic acid produced by glycolysis:

i. Lactic acid fermentation

ii. ALCOHOLIC fermentation

iii. Aerobic RESPIRATION

The correct option is (b) TWO

The best I can explain: During the process, two molecules of NADH are PRODUCED from the metabolism of two molecules of PYRUVIC ACID i.e. produced from one glucose MOLECULE during glycolysis.

The CORRECT option is (B) False

Explanation: During oxidation within a cell, all the ENERGY contained in the respiratory substrate is not released in a single step because then all the energy would be LOST in a single step and the cell would not be able to store the SYNTHESISED energy for its future use.

Right option is (d) ENERGY can never be stored

The explanation: Certain assumptions of the respiratory BALANCE sheet include that none of the intermediates in the PATHWAY are utilised to synthesise any other compound. Respiration is a sequential pathway and NADH synthesised in GLYCOLYSIS is transferred into the MITOCHONDRIA and undergoes oxidative phosphorylation.

The correct option is (a) More than 1

The best I can explain: ORGANIC acids have R.Q value more than ONE. But when PROTEINS are respiratory substrates the RATIO would be about 0.9. Pure proteins or fats are never USED as respiratory substrates.

Right option is (C) Complex V

Best explanation: In the ELECTRON TRANSPORT system, Complex I, II, III and IV are RELATED to the transport of only electrons in the mitochondria. Complex V is the only complex in ETS which is involved in proton transport.

The CORRECT answer is (a) True

The best I can explain: Link REACTION or gateway reaction involves the conversion of pyruvic acid into Acetyl CoA after the combination with coenzyme A containing Sulphur. The WHOLE reaction takes place due to the catalyzation EFFECT produced by the ENZYME pyruvate dehydrogenase.

The correct option is (C) Carbon skeletons

Best explanation: Carbon skeletons are USED as precursors for the biosynthesis of other biomolecules as the oxidation of these carbon skeletons leads to the FORMATION of ATP which is STORED by the cells to be utilised in various-energy requiring processes of the ORGANISMS.

Right answer is (d) 0.7

For explanation: When fats are used in RESPIRATION, the RQ is LESS than 1. For a fatty ACID, tripalmitin, the ratio of the VOLUME of CARBON dioxide evolved to the volume of oxygen evolved is 0.7.

Right ANSWER is (b) 2 ATP

The explanation is: In fermentation, there is a net gain of only two molecules of ATP for each molecule of glucose DEGRADED to pyruvic acid whereas MANY more molecules of ATP are generated under aerobic CONDITIONS.

The CORRECT answer is (a) ACETYL CoA would be withdrawn from the pathway

To explain: When fatty ACIDS are to be used as substrates, then they would be BROKEN down to acetyl CoA before entering the respiratory pathway, but when organisms NEED to synthesise fatty acids, acetyl CoA would be withdrawn from the respiratory pathway for it.

The correct option is (b) 3

The explanation is: In glycolysis, two molecules of NADH are formed at the TIME of oxidation of GLYCERALDEHYDE 3-phosphate to 1, 3-diphosphoglycerate which give rise to 6 ATP. This is converted into RESPECTIVE ATP forms during Electron Transport SYSTEM.

The correct choice is (c) Yes, they work simultaneously

To EXPLAIN: The ASSUMPTIONS made in the respiratory balance sheet are not valid for the living SYSTEM. All pathways work simultaneously and do not take PLACE one after ANOTHER.

The correct choice is (b) False

Explanation: Pyruvate is the product of glycolysis which occurs in the cytoplasm of all the living organisms. Therefore, for pyruvate to enter KREB’s cycle, it enters in the mitochondrial matrix where it undergoes oxidative decarboxylation as from 2 MOLECULES of pyruvate, 6 molecules of carbon dioxide are RELEASED.

Right answer is (c) Chloroplasts

Easiest explanation: Photosynthesis takes place within the chloroplasts in the EUKARYOTES whereas the breakdown of complex molecules to YIELD energy takes place in the CYTOPLASM and the MITOCHONDRIA.

Correct option is (B) Breaking down PROCESSES

For explanation: Catabolism refers to the breaking down processes that OCCUR WITHIN the living organisms. CATABOLIC reactions include glycolysis, the tricarboxylic citric acid cycle, breakdown of fatty acids, etc.

Correct answer is (b) False

Best explanation: Ubiquinone receives electrons from Complex I which is NADH dehydrogenase. It ALSO receives reducing equivalents via Complex II which is FADH2 that is generated during the oxidation of succinate in the citric acid CYCLE.

Correct OPTION is (C) Two

For explanation I would say: Two steps of DECARBOXYLATION leads to the formation of ketoglutaric acid. When citric acid is FORMED in the cycle, it then forms cis-acotinic acid and then isocitric acid. Isocitric acid further forms oxalosuccinic acid which FINALLY forms ketoglutaric acid in the presence of oxalosuccinate decarboxylase enzyme.

Right OPTION is (a) HANS Krebs

To explain: Tricarboxylic acid CYCLE, more commonly known as Kreb’s cycle was elucidated by Hans Krebs who FIRST discovered it in the FLIGHT muscles of pigeon.

The correct option is (d) CO2 and ethanol

Explanation: In the process of 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.

Correct CHOICE is (d) CO2 and H2O

Explanation: The complete combustion of glucose, which PRODUCES CO2 and H2O as end PRODUCTS, yields energy most of which is GIVEN out as heat. If this energy is to be useful to the cell, it should be able to utilise it to synthesise other molecules that the cell requires.

Correct option is (d) DNA

The explanation is: Nucleic acids like DNA and RNA are never oxidised to release ENERGY because these are integrated parts of the cell and they are used to carry or express different genes in the human beings which carry out different FUNCTIONS like the FORMATION of proteins, FATS and CARBOHYDRATES.