Biology Chapter 14 Respiration In Plants

1. Incomplete break down. There is incomplete breakdown of repiratory substrate.

2. Incomplete oxidation. At least one of the products of anaerobic respiration is organic. It can be further oxidised to release energy.

3. Re-utilization. NADH₂ produced during glycolysis is often re-utilized.

4. No A TP formation. ATP formation does not, occur during regeneration of NAD⁺.

5. Absence of ETC. Electron transport chain is absent.

6. No use of oxygen. Oxygen is not used for receiving electrons and protons.

Oxidative phosphorylation. It is the synthesis of ATP molecules from ADP and iP (inorganic phosphate) during aerobic respiration. ADP + i P + energy ----> ATP

The energy is evolved during electron transport chain and H⁺ shift from the outer chamber of mitochondria into inner chamber through F₀-F₁ particles. When electron is passing through F1 particle or head of oxysome then its energy is taken by ADP + iP to form ATP. Therefore oxysome acts as ATPase.

When one molecule of NADH is oxidized then 3 ATP molecules are produced. When one molecule of FADH₂ in oxidized, 2 ATP molecule are produced.

In eucaryotic cells, one molecule of glucose on oxidation produces 36 ATP molecules.

During aerobic oxidation in prokaryotic cell, of one glucose molecule 38 ATP molecules are produced. ATP’s are the energy currency of the cell.

Importance of step-wise release of energy :

Step-wise oxidation of food in cells is advantageous in following ways :

I. Due to step-wise release of chemical bond energy, a maximum proportion of it is used in the synthesis of ATP molecules.

2. Temperature of cell does not rise as total energy is not produced at one time.

3. The rate of energy output can be controlled according to cells requirement by increasing or decreasing the action of the enzymes at different steps.

4. Intermediates of the pathway can be used for the synthesis of other biomolecules like amino acids.

Fermentation is the incomplete breakdown of carbohydrates under anaerobic conditions. It is of two types:

A. Alcoholic fermentation : It occurs in fungi such as yeast, Rhizopus etc. and bacteria. It can be described in 2 steps :

Step I : Pyruvic acid is decarboxylated into acetaldehyde in the presence of enzyme pyruvate decarboxylase and CO₂ is liberated.

Step II : Acetaldehyde is reduced to ethyl alcohol in the presence of enzyme alcoholic dehydrogenase and NADH₂ is oxidised to NAD. There is loss of energy stored in ethyl alcohol.

Importance.
I. Alcoholic fermentation is common in yeasts which are used in industrial preparation of ethyl alcohol from molasses. It is the basic process underlying the production of beers and wines.

2. Yeasts are used in baking industry as CO₂ produced during alcoholic fermentation raises its dough.

B. Lactic acid fermentation : Lactic acid fermentation is common in animals and certain bacteria. In vertebrates, lactic acid formed in muscles in the anaerobic conditions.

The impor:
1. RQ gives information about type of respiration i.e. aerobic or anearobic.

2. The type of respiratory substrate can be known.

1. Cellular respiration uses oxygen while fermentation does not require oxygen.
2. Cellular respiration produces 38 ATP, while fermentation produces only 2 ATP.
3. Cellular respiration is more efficient than fermentation in the generation of ATP.
4. In aerobic respiration the glucose is completely broken down into carbondioxide and water. While in fermentation the glucose is partialy broken down into carbon dioxide and ethanol/lactic acid. 

C₆H₁₂O₆+ 6O₂→ 6CO₂ + 6H₂O+ 684 K. cal.

Most common respiratory substrate is glucose, because it gets easily oxidised.

Amphibolic pathway : Respiratory pathway is involved in both anabolism and catabolism, thus the respiratory pathway is an amphibolic pathway rather than as a catabolic one.

Respiration involves the breakdown of substrates. The respiratory process has traditionally been considered a catabolic process and the respiratory pathway as a catabolic pathway.

The intermediates of the respiratory pathway are withdrawn and used for the synthesis of the other substrates.
Fatty acids are usually broken down to acetyl-CoA before entering the respiratory pathway. here it is used as a substrate. But when the organism needs to synthesise fatty acids, acetyl CoA is withdrawn from the respiratory pathway for the synthesis of fatty acids. Hence, the respiratory pathway has both synthesis and breakdown of fatty acids. 

Similarly, respiratory intermediates, are the link in the synthesis and breakdown of proteins too. Thus, it is amphibolic pathway.

1. Fats would need to be broken down into glycerol and fatty acids first. If fatty acids were to be respired they would first be degraded acetyl CoA and enter the pathway.

2. Glycerol would enter the pathway after being converted to phosphoglyceraldehyde.

3. The proteins would be degraded by proteases and the individual amino acids depending on their structure would enter the pathway at some stage within the krebs cycle or even as pyruvate or acetyl CoA.

The main steps in aerobic respiration are as follows :

1. Glycolysis.

2. Oxidative decarboxylation of pyruvic acid to acetyl coenzme-A.

3. Tricarboxy acid cycle or Krebs cycle.

4. Electron transport system.

5. Chemiosmotic ATP synthesis.

The calculations for the net gain of ATP is usually based on the following assumptions :

i.  All the reactions are sequential and follow a orderly pathway , with one substrate forming the next and with glycolysis, TCA cycle and ETS
pathway following one after another.
ii. The NADH synthesised in glycolysis is transferred into the mitochondria where it is subject to oxidative phosphorylation.
iii. The intermediates of the pathway are not utilised to synthesise any other compound.
iv. Only glucose is used as the respiratory substrate and no alternative r alternative substrates are used or enter the pathway at any of the intermediary stages.

The assumptions made during the calculation of ATP are :

(a) The reaction like glycolysis, TCA cycle, and ETS, are assumed to occur in a sequential and orderly pathway.

(b) NADH produced during the process of glycolysis enters into mitochondria to undergo oxidative phosphorylation.
(c) Glucose is assumed to be the only substrate
(d) It is assumed that no other molecule enters the pathway at the intermediate stages.

(e) The intermediates produced during respiration are not utilized in any other process.

 ETS or the Electron transport chain is the pathway through which the electron pass from one carrier to another. The ETS is found in the inner mitochondrial membrane.
Electrons from NADH produced in the mitochondrial matrix during citric acid cycle are oxidised by NADH dehydrogenase (complex I), and electrons are then transferred to ubiquinone located within the inner membrane.
Ubiquinone also receives reducing equivalents via FADH2 (complex II) that is generated during oxidation of succinate in the citric acid cycle.
The reduced ubiquinone (ubiquinol) is then oxidised with the transfer of electrons to cytochrome c via cytochrome bc 1 complex (complex III). The cytochrome c acts as a mobile carrier between complex III and cytochrome c oxidase complex, containing cytochrome a and a₃, along with copper centres (complex IV).

During the transfer of electrons from each complex, ATP is produced from ADP and inorganic phosphate by the action ATP synthase (complex V).
The amount of ATP produced depends on the molecule, which has been oxidized. 2 ATP molecules are produced by the oxidation of one molecule of NADH. One molecule of FADH2, on oxidation, gives 3 ATP molecules.

Respiratory Quotient is the ratio of the volume of CO₂ evolved to the volume of O₂ consumed in respiration.
The RQ for carbohydrates is 1. The RQ for fat and protein is less than 1.

For example: Calculations for a fatty acid, tripalmitin

2(C₅₁H₉₈O₆) + 145O₂ → 102CO2 + 98H₂O + energy

RQ = Volume of CO₂ evolved/Volume of O₂ consumed

      = 102 CO₂/145O₂ = 0.7

C.

cristae of mitochondria

Cytochromes are present on the cristate, i.e. inner foldings of mitochondria. Cytochromes are iron (heme) containing proteins primarily responsible for transfer of electrons in ETC from ubiquinone to complex-V for generation of ATP(energy molecules) and terminal acceptor O₂ in electron transport chain.
They are also called respiratory pigments, which are capable of performing both the oxidation and reduction reactions.

D.

glycolysis

Glycolysis is the first stage of the breakdown of glucose in the cytoplasm of the cell without using oxygen (electron acceptor). It is a stepwise process in which one molecule of glucose breaks into two molecules of pyruvic acid and a net gain of energy is 2 ATP and 2NADH₂ molecules.
The stepwise breakdown of the respiratory substrate to CO₂ and H₂O in presence of oxygen is referred as aerobic respiration. It is a catabolic process and generates a large amount of energy to form ATP.
Anaerobic respiration n micro-organisms are called fermentation. Alcoholic fermentation is a breakdown of glucose into ethyl alcohol and CO₂ in presence of enzyme of micro-organism. Photorespiration is light-induced oxidation of photosynthetic intermediates with the help of oxygen without releasing energy.

A.

malonate

Succinic dehydrogenase oxidised the succinate to fumarate. In eukaryotes, succinate dehydrogenase is tightly bound to the inner mitochondrial membrane, in prokaryotes to the plasma membrane. Electrons pass from succinate through the FAD and iron-sulphur centres before entering the chain of electron carriers in the mitochondrial inner membrane malonate, an analogue of succinate is a strong competitive inhibitor of succinate dehydrogenase and therefore, blocks the activity of citric and cycle.
In Krebs cycle, the reversible hydration of fumarate to malate is catalysed by fumarase enzyme.
In the last reaction of Krebs cycle NAD- linked L-malate dehydrogenase catalyses the oxidation of L-malate to oxaloacetate.
The isocitrate dehydrogenase in Krebs cycle catalyses oxidative decarboxylation of isocitrate to form alpha-ketoglutarate, which in next step through oxidative decarboxylation converted to succinyl Co-A

C.

a proton gradient forms across the inner membrane

The production of ATP with the help of energy liberated during oxidation of reduced coenzymes and terminal oxidation is called oxidative phosphorylation. Peter Mitchell (1961) put forward a hypothesis known as a chemiosmotic hypothesis for ATP synthesis. According to this when electrons flow from dual proton, electron carrier to a non-hydrogen carrier the H⁺ in the intermembranous space than the matrix. Due to proton motive force, the protons flow back and energy liberated during this backflow of protons activate ATPase present in F₁ head to synthesise ATP. 

A.

ATP in small stepwise units

Glycolysis, Krebs cycle and electron transport system are meant for ATP synthesis in different steps. ATP is the energy currency of cell.

B.

The enzymes of the electron transfer chain are embedded in the outer membrane

In mitochondria, the enzymes of electron transport chain are found in the inner membrane while outer membrane contains enzymes involved in mitochondrial lipid synthesis and those enzymes that convert lipid substrates into forms that are subsequently metabolised in the matrix.
The outer membrane resembles a sieve that is permeable to all molecule of 10,000 daltons mole. weight or less including small proteins.
The inner membrane is impermeable and highly convoluted, forming a series of infoldings, known as cristate, in the matrix space.

B.

Thirty

30 ATP molecules could be generated from 686 Kcal energy.

A.

The residual air in lungs slightly decreases the efficiency of respiration in mammals

Residual air is the air that remains in lungs after the most forceful expiration. It is about 1200 ml. As the residual air remains in the lungs therefore it has no effect on respiration efficiency.

D.

The cycle starts with condensation of acetyl group (acetyl CoA) with pyruvic acid to yield citric acid

Krebs cycle starts with condensation of acetyl CoA (2C) with oxaloacetic acid (4C) to form citric acid (6C).

A.

Ovary wall is absent

Gymnosperms are commonly known as 'naked seed plants because the ovary wall is not present and hence, the ovules remain unprotected or naked.

C.

Kreb's cycle

Decarboxylation is a process in which carboxyl group is removed in order to make carbon dioxide. Acetyl groups in the TCA cycle pass round the cycle and two carbon atoms are lost in the formation of carbon dioxide.

A.

greater than pure solvent

Osmotic Pressure of a solution is greater than pure pure solvent. When a solution is seperated from a pure solvent by the help of semi- permeable membrane, the solvent begins to flow towards the solution.

B.

38

In liver cells and prokaryotic cells, 38 ATP are produced by the complete oxidation of one
molecule of glucose.

Glycolysis

2 ATP directly = 2 ATP 
2 mol. of NADH = 6 ATP
Pyruvic acid to Acetyl Co-A 2 mol. of NADH Citric acid 6 mol. of NADH cycle
2 mol. of FADH  = 4 ATP
2 mol. of GTP =  2 ATP
Total = 38 ATP

C.

alcohol and CO₂

The anaerobic respiration occurs in many bacteria, some fungi, germinating seeds, some fruits and during exergenous exercise. It involves the incomplete breakdown of sugars forming C₂H₅OH and CO₂ as end products and 27 kcal energy is released.

B.

Electron transport chain

In glycolysis, 4 ATP and 2 NADH₂ molecules are formed. These 2 NADH₂ molecules go to electron transport chain.

In oxidative decarboxylation no ATP molecules are formed but two molecules of NADH₂ are formed from two molecules of pyruvate. And both NADH₂ molecules go to ETC (Electron Transport Chain). 

In Krebs cycle 2 ATP, 6NADH₂ and 2FADH₂ molecules are formed from two molecule of acetyl Co-A. These NADH₂ and FADH₂ go to ETC.

In ETC all NADH₂ and FADH₂ pass to electron carriers and yield 3 ATP and 2 ATP molecules per NADH₂ and FADH₂ respectively. Thus,
$\to$4 ATP are formed in glycolysis
$\to$2 ATP in Krebs cycle and
$\to$34 ATP from electron transport chain
$\to$40 ATP
$\to$2 ATP molecules are used during glycolysis.
So, net gain of ATP molecules during one complete oxidation of a glucose molecule is 38 ATP.

A.

proton gradient

Chemiosmotic hypothesis for oxidative phosphorylation (ATP synthesis) was proposed by Peter Mitchell in 1961. He was awarded Noble Prize in 1978. This theory is based on proton gradient.

B.

Co- A

The respiratory decomposition of fatty acids is known as beta oxidation, which occurs in liver and adipose tissue. Activation of fatty acids takes place, then dehydrogenation of activated fatty acid takes place. It is followed by hydration. The $\mathrm{\beta }$-hydroxyl acyl derivative is converted to $\mathrm{\beta }$-keto derivative, which then reacts with Co-A. And it leads to oxidation.

D.

36

There is a total gain of 38 ATP molecules during aerobic respiration. Out of these two molecules of ATP, two are required for transporting the NADH produced in glycolysis (in cytoplasm) into the mitochondria for further oxidation, hence the net gain of ATP is 36 molecules.

D.

castor

Respiratory Quotient is the ratio of the volume of carbon- dioxide evolved to that of oxygen consumed by an organism tissue, or cell in a given time. 

In fats, the value of R.Q. is less than one.

A.

oxygen

Oxygen is the terminal acceptor of electron in Electron Transport System(ETS), which in the presence of proton forms a water molecule.

A.

cytosol

Glycolysis or Embden–Meyerhof–Parnas pathway takes place in cytoplasm. It is a common phase between aerobic and anaerobic respiration. The enzymes occur in cytosol.

B.

If both assertion and reason are true but reason is not the correct explanation of assertion.

One of the two phosphates of 1, 3 biphosphoglycerate (BPGA) is linked by high energy bond. It can synthesise ATP and form 3-phosphoglycerate by phosphoglycerate kinase enzyme. The direct synthesis of ATP from metabolites is called substrate level phosphorylation.

C.

Phosphorylase

Transfer of phosphate group from ATP to a carbohydrate is referred to as phosphorylation and is carried out in the presence of phosphorylase enzymes. E.g., glucose (a carbohydrate) is phosphorylated to glucose-6-phosphate by ATP in the presence of enzyme hexokinase or glucokinase and Mg²⁺.

A.

If both assertion and reason are true and reason is the correct explanation of assertion.

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.

RQ = Volume of CO₂ evolved$/$ Volume of O₂ consumed.

The respiratory quotient depends upon the type of respiratory substrate used during respiration. When carbohydrates are used as substrate and are completely oxidised, the RQ will be 1, because equal amounts of CO₂ and O₂ are evolved and consumed respectively.

C₆H₁₂O₆ +6O_2 $\to$ 6CO₂ +6H₂O+ Energy

   RQ = 6CO_2$/$6O_{2 =} 1

A.

smaller

The intraspecific competition makes the size of niche smaller due to keen competition among the members.

A.

If both assertion and reason are true and reason is the correct explanation of assertion.

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.

RQ = Volume of CO₂ evolved$/$ Volume of O₂ consumed.

The respiratory quotient depends upon the type of respiratory substrate used during respiration. When carbohydrates are used as substrate and are completely oxidised, the RQ will be 1, because equal amounts of CO₂ and O₂ are evolved and consumed respectively.

C₆H₁₂O₆ +6O_2 $\to$ 6CO₂ +6H₂O+ Energy

   RQ = 6CO_2$/$6O_{2 =} 1

C.

oxalosuccinic acid to $\mathrm{\alpha }$- ketoglutaric acid

Oxalosuccinate is decarboxylated to form $\mathrm{\alpha }$- ketoglutarate through the enzyme decarboxylase. It is one of the step involved in Krebs' cycle. It releases one molecule of CO₂.

Oxalosuccinate $\underset{{\mathrm{Mg}}^{2+}}{\overset{\mathrm{Decarboxylase}}{\to }}$ $\mathrm{\alpha }$- ketoglutarate + CO₂

C.

CoQ $\to$Cyt c is H⁺ yielding site and aa₃ $\to$O₂ is H⁺ absorbing site

In electron transport chain electrons transport through a series of carriers. H⁺ of NADH⁺ (received from Kreb' s cycle) is accepted by FAD as a result of which FAD is reduced to FADH⁺ and NADH⁺ is oxidised to NAD. Reduced FADH⁺ is oxidised by CoQ with the formation of CoQH⁺. H⁺ ions then move to Cyt b, then Cyt c, Cyt a and Cyt aa₃. Ultimately these H⁺ are acceped by O₂ and H₂O is formed.

D.

If both assertion and reason are false

Glycolysis is a process in which a molecule of glucose (6C) is degraded in a series of enzyme- catalyzed reactions to yield two molecules of pyruvate (3C). This process releases energy (ATP) and reducing power (NADH₂).  It is a first step of respiration that occurs inside the cytoplasm and is independent of O₂.

In glycolysis, two molecules of ATP are consumed during double phosphorylation of glucose to form Fructose 1, 6 Diphosphate. Four molecules of ATP are produced in the conversion of 1, 3- Diphosphoglycerate to 3- Phosphoglycerate and Phosphenol Pyruvate to Pyruvate whereas, two molecules of NADH₂ are formed during oxidation of glyceraldehyde 3-phosphate to 1, 3-Diphosphoglycerate. Since, each NADH is equivalent to 3 ATP, so net gain in glycolysis is 8 ATP.

A.

Acetyl Co- A

Glycolysis is the first step of respiration in which glucose is broken down to pyrurate.

During glycolysis 1 molecule of glucose is converted to 2 molecules of pyruvic acid in the cytoplasm. These two molecules of pyruvic acid are then converted to acetyl Co-A by decarboxylation. This acetyl Co-A is the connecting link between glycolysis and Kreb's cycle and functions as substrate entry for Kreb's cycle. Acetyl Co-A thus formed participates in Kreb's cycle and combines with oxaloacetic acid to form citrate.

C.

If assertion is true but reason is false

Oxysomes or F₀- F_i  particles are present on the inner mitochondrial membrane. The F_i headpiece of oxysome functions as ATP-synthetase which synthesises ATP from ADP and pi (inorganic phosphate) using energy from proton gradient or ATP synthetase becomes active in ATP formation only when there is a proton gradient having high concentration of protons on F₀ side (base) as compared to F_i side (head piece) of F₀- F_i particles or oxysomes.

A.

O₂

The biological oxidation requires oxygen (O₂) continuously in Krebs cycle. It is essential forthe oxidation of food materials. It results into the evolution of energy for different activities of the body.

D.

oxidative phosphorylation

An electron transport chain (ETC) is a series of complexes that transfer electrons from electron donors to electron acceptors via redox (both reduction and oxidation occurring simultaneously) reactions, and couples this electron transfer with the transfer of protons (H⁺ ions) across a membrane.

The efficiency of oxidative phosphorylation is 40% higher than any other energy conversion system. It is one of the key processes in respiration in which the energy extracted from food is trapped and made available to the living cells.

C.

Direct oxidation pathway

By pentose phosphate pathway or hexose monophosphate (HMP) Shunt or Warburg Dickens pathway or direct oxidation pathway one glucose is completely oxidised without glycolysis. In this process 12 NADPH, are formed witch are equivalent to 36 ATP molecules.

D.

zero

The (light) compensation point is the light intensity on the light curve where the rate of photosynthesis exactly matches the rate of cellular respiration. At this point, the uptake of CO₂ through photosynthetic pathways is equal to the respiratory release of carbon dioxide, and the uptake of O₂ by respiration is equal to the photosynthetic release of oxygen.

In assimilation terms, at the compensation point, the net carbon dioxide assimilation is zero. Leaves release CO₂ photorespiration and cellular respiration, but CO₂ is also converted into carbohydrate by photosynthesis. Assimilation is therefore the difference in the rate of these processes. At a normal partial pressure of CO₂, there is irradiation at which the net assimilation of CO₂ is zero.

B.

Succinic acid➔ Fumaric acid

In biochemistry, flavin adenine dinucleotide (FAD) is a redopx-active coenzyme associated with various protiens, which is involved with several important enzymatic reactions in metabolism. A flavoprotien is a protein that contains a flavin group, this may be in the form of FAD or flavin mononucleotide(FMN).

A.

2 

The net energy gain in fermentation is 2 ATP molecules/glucose molecule. In both lactic acid and alcoholic fermentation, all the NADH produced in glycolysis is consumed in fermentation, so there is no net NADH production, and no NADH to enter the ETC and form more ATP.

C.

Lactic acid

If the breathing rate and blood flow cannot supply enough oxygen to your working muscles, the body turns to anaerobic respiration. This is the production of energy without the use of oxygen. This system works by producing lactic acid to facilitate energy production.

C.

TCA cycle

The tricarboxylic acid cycle (TCA cycle) is a series of enzyme-catalyzed chemical reactions that form a key part of aerobic respiration in cells. This cycle is also called the Krebs cycle and the citric acid cycle.

C.

mitochondrion

Mitochondria function during aerobic respiration to produce ATP through oxidative phosphorylation (def). The respiratory enzymes and electron carriers for the electron transport system are located within the inner mitochondria membrane.

C.

Glucose-6-phosphate

Glucose-6 phosphate yields less than 4 kcal/mol, when its phosphate bond is hydrolysed.

C.

1520

Breakdown (complete oxidation) of one molecule of glucose by aerobic respiration produces 38 ATP molecules. So, complete oxidation of 40 molecules of glucose will produce.

40 x 38 ATP = 1520 ATP molecules.

B.

ATP

Pathway A:- Glycolysis

Pathway B:- Kreb's Cycle

Pathway C:- Oxidative Phosphorylation

Arrow in the above 3 pathways represent net reactants or products which are as follows-

1 - ADP or NAD⁺

2 - Pyruvate

3 - NADH

4 - ATP

5 - ADP, NAD⁺ or FAD

6 and 7 - FADH₂ and NADH

8 - ATP or CO₂

9 and 10 - O₂ and ADP

11 and 12 - H₂O and ATP  

D.

Acetyl Co-A

Acetyl Co-A is common to respiration mediated breakdown of fats, carbohydrates and proteins.

Glucose and fructose are phosphorylated to give rise to glucose 6-phosphate by the activity of the enzyme hexokinase. It then converts into fructose 6 phosphate and further to fructose 1-6-bisphosphate. Pyruvic acid is the end product of glycolysis.

A.

2

During the course of electron transfer, when electrons passes from one carrier molecule to another in the ETC. They get coupled to ATP synthase for the production of ATP from ADP and Pi (inorganic phosphate). The number of ATP molecule synthesised depends upon the nature of the electron donor. One molecule of FADH₂ on oxidation provides or produces 2 molecules of ATP because its redox potential is higher than NADH and thus, enters the ETS after by passing the first site of phosphorylation.

B.

P= 8, Q= 6,R= 24

Out of the 38 molecules of ATP produced upon aerobic respiration of glucose. The breakup of ATP during complete aerobic respiration is as follows:

In eukaryotic cells, 2 molecules of ATP are sepnt for transporting 2 molecules of NADH formed during glycolysis to the mitochondria. Hence, net gain is 36 molecules of ATP.

C.

mitochondrial matrix

TCA cycle enzymes are soluble proteins located in the mitochondrial matrix space, except for succinate dehydrogenase, which is an integral membrane protein that is firmly attached to the inner surface of the mitochondrial inner membrane, where it communicates directly with components in the respiratory chain.

C.

Net gains is one molecule of NADH and three molecules of ATP for every molecule of glucose broken down.

Net gain of Glycolysis is two molecules of NADH and two molecules of ATP for every molecules of glucose broken down.

B.

Statement II is correct and statement I is incorrect

$\mathrm{\alpha }$- ketoglutarate dehydrogenase catalyses conversion of $\mathrm{\alpha }$-ketoglutarate acid, i.e. a 5C compound to 4C Succinyl Co-A. The reaction is as follows

A.

A - 2; B - 4; C - 1; D - 3

C.

Electron transport chain

During the process of complete oxidation of glucose, ATP molecules are formed from ADP. The stage which yields the maximum number of ATP is electron transport chain.

C.

C₆H₁₂O₆ $\to$2C₃H₄O₃ + 2CO₂

Glycolysis is the process in which glucose molecule breakdown into two pyruvate (3 carbon) molecule. During this process, 2 net ATP molecules are produced. It is an anaerobic process of oxidation which occur in stroma of mitochondria.

A.

glucose

Glycogen is a polymer of D- glucose and is highly branched and the branching occurs in 10-12 glucose units. Hence, the repeating unit in glycogen is Glucose.

B.

RuDP carboxylase

RuDP Carboxylase is made up of rubisco protein which is most abundant plant protein on earth.

A.

Phosphoenol pyruvate carboxykinase - Gluconeogenesis

Phosphoenol pyruvate or PEP is a primary acceptor of CO₂. It combines with CO₂ in the presence of PEP carboxylase to form oxaloacetic acid or oxaloacetate.

D.

None of these

Synthesis of ATP from NADH (H⁺) takes place only under aerobic condition. In aerobic condition one NADH+ H⁺ provides 3 ATP molecules.

C.

cytochrome- a₃

The cytochrome- a₃ is an electron carrier which contains copper with iron. It picks up electrons and through copper, it hands over electrons to oxygen. Oxygen accepts electrons finally.

C.

Krebs' cycle

Decarboxylation is involved in Kreb's cycle. There are 8 reactions which takes place in Kreb's cycle and are as follows-

1. Condensation
2. a. Dehydration          b. Hydration
3. Oxidative decarboxylation
4. Oxidative decarboxylation
5. Substrate level phosphorylation
6. Dehydrogenation
7. Hydration

Decarboxylation is the removal of carbon from a compound to make CO₂.

A.

fermentation

Fermentation is the process anaerobic process after glycolysis. It is of two types- alcoholic fermentataion and Lactic acid formation.

Kreb's cycle is the aerobic process after glycolysis.

Decomposition is the breakdown of complex organic compound by micro-organisms into simpler molecules of availability.

D.

Ethyl alcohol + CO₂

The yeast causes anaerobic respiration (fermentation). In the fermentation the pyruvate is broken down to form ethyl alcohol (C₂H₅OH), CO₂ and NAD⁺. The ethyl alcohol is excreted.

B.

less than one

Respiratory Quotient (RQ) is the ratio of the volume of carbon dioxide produced to the volume of oxygen consumed in respiration over a period of time. The RQ is less than one (0.7) in case of fat.

D.

cytochrome a₃

Cytochrome C oxidase complex of electron transport chain contain cytochrome a and cytochrome a₃. Cytochrome a₃ is the terminal which donate electron to oxygen.