Anaerobic respiration Questions in English

(B) The correct answer is $B$. $Clostridium$ is an obligate anaerobe,meaning it can only respire and grow in the absence of oxygen. While some other bacteria like $Lactobacillus$ are facultative anaerobes,$Clostridium$ species are strictly anaerobic organisms that perform fermentation in the absence of oxygen.

(A) Putrefaction is the anaerobic decomposition of organic matter,especially proteins,by microorganisms. This process typically occurs in the absence of oxygen and leads to the breakdown of nitrogenous organic compounds into simpler substances,often releasing foul-smelling gases such as hydrogen sulphide $(H_2S)$,ammonia $(NH_3)$,and various amines. Therefore,the correct term for this process is Putrefaction.

(D) Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes.
It is not a universal process performed by all microorganisms,fungi,or bacteria.
Specific groups of microorganisms,such as certain species of yeast (fungi like $Saccharomyces$ $cerevisiae$) and various bacteria (e.g.,$Lactobacillus$),are capable of performing fermentation to generate energy under anaerobic conditions.
Therefore,fermentation is carried out by some fungi and some bacteria.

(D) During strenuous exercise,the demand for oxygen in muscle cells exceeds the supply. Under these anaerobic conditions,muscle cells perform anaerobic respiration (lactic acid fermentation). In this process,glucose is first broken down into pyruvic acid via glycolysis,and then the pyruvic acid is reduced to lactic acid by the enzyme lactate dehydrogenase. This allows for the regeneration of $NAD^+$ so that glycolysis can continue to produce $ATP$.

(C) Pasteur's effect is the inhibition of the process of fermentation by oxygen. When oxygen is introduced to an anaerobic culture of yeast,the rate of glucose consumption decreases significantly because the organism switches from fermentation (which is less efficient) to aerobic respiration (which is more efficient for $ATP$ production). Thus,the presence of oxygen suppresses the fermentation process.

(A) The conversion of pyruvic acid into lactic acid is a type of anaerobic respiration (fermentation).
In this process,pyruvic acid is reduced to lactic acid by the enzyme lactate dehydrogenase.
This reaction occurs in the absence of oxygen,as oxygen is not required as a terminal electron acceptor in this pathway.
Therefore,the primary condition for this conversion is the absence of oxygen.

(D) The correct answer is $D$. The $Pasteur$ $effect$ refers to the phenomenon where the rate of glycolysis increases significantly in the absence of $O_2$ (anaerobic conditions) compared to its rate in the presence of $O_2$ (aerobic conditions). This occurs because,under anaerobic conditions,the cell must increase the rate of glucose breakdown to produce sufficient $ATP$ to meet its energy requirements,as the $TCA$ cycle and oxidative phosphorylation are inhibited.

(D) is the correct answer. Anaerobic respiration is considered toxic to plants because it leads to the accumulation of toxic end products like ethanol or lactic acid. Furthermore,it produces an insufficient amount of energy compared to aerobic respiration,which can lead to the cessation of vital metabolic processes and cellular damage.

(C) In anaerobic respiration, glucose undergoes incomplete oxidation in the absence of oxygen.
This process, often called fermentation, results in the production of ethanol (alcohol) and carbon dioxide $(CO_2)$.
The chemical equation is: ${C_6}{H_{12}}{O_6} \xrightarrow{} 2{C_2}{H_5}OH + 2C{O_2} + 21 \, \text{kcal}$.

(A) Anaerobic respiration is a process where organisms produce energy in the absence of oxygen.
$Yeast$ (a fungus) is the most classic example used in biology to demonstrate fermentation, which is a type of anaerobic respiration.
While some plant tissues can undergo anaerobic respiration under stress, $Yeast$ is the organism most widely recognized and studied for its ability to perform fermentation in the absence of oxygen.

(B) Alcohol (ethanol) is produced during the process of anaerobic respiration,specifically in yeast cells through a process called fermentation.
In this process,glucose is incompletely broken down in the absence of oxygen to produce ethanol,$CO_2$,and a small amount of energy $(ATP)$.

(C) During anaerobic respiration (lactic acid fermentation),pyruvic acid is reduced to lactic acid by the enzyme lactate dehydrogenase.
This process utilizes $NADH + H^+$ produced during glycolysis.
Since glycolysis produces a net gain of $2\, ATP$ molecules per glucose molecule,and the subsequent conversion of pyruvic acid to lactic acid does not produce any additional $ATP$,the net gain remains $2\, ATP$ molecules per glucose molecule.
Therefore,the process results in a gain of $2\, ATP$ molecules.

(C) Fermentation is a type of anaerobic respiration that occurs in microorganisms like yeast.
In this process, sugars (like glucose) are incompletely oxidized in the absence of oxygen.
The chemical equation for alcoholic fermentation is: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + \text{Energy}$.
Therefore, the end products are alcohol (ethanol) and carbon dioxide $(CO_2)$.

(A) Fermentation is a type of anaerobic respiration where organic compounds are broken down in the absence of oxygen.
It involves the incomplete oxidation of carbohydrates (like glucose) into products such as ethanol or lactic acid.
Since both options $A$ and $B$ describe the process,but fermentation is specifically defined as a form of anaerobic respiration involving incomplete oxidation,the most accurate description is that it is a form of anaerobic respiration.

(C) The conversion of pyruvic acid to ethyl alcohol occurs during anaerobic respiration (fermentation) in yeast.
Step $1$: Pyruvic acid is converted into acetaldehyde by the enzyme $Pyruvate \ decarboxylase$,releasing $CO_2$.
Step $2$: Acetaldehyde is then reduced to ethyl alcohol by the enzyme $Alcohol \ dehydrogenase$,using $NADH + H^+$ as a reducing agent.
Therefore,both decarboxylase and dehydrogenase enzymes are involved in this process.

(B) During anaerobic respiration in yeast,glucose undergoes fermentation to produce ethanol $(C_2H_5OH)$,carbon dioxide $(CO_2)$,and a small amount of energy $(ATP)$.
The chemical equation for this process is: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + 2ATP$.

(B) Fermentation is an anaerobic process where glucose is incompletely broken down into ethanol and carbon dioxide.
The chemical equation for alcoholic fermentation is: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + 18 \, kcal$.
Option $A$ represents aerobic respiration.
Option $C$ and $D$ represent photosynthesis.

(B) In anaerobic respiration,only glycolysis occurs. Glycolysis is the process of breaking down glucose into pyruvate,which takes place in the cytoplasm of the cell. Since anaerobic respiration does not involve the Krebs cycle or the electron transport chain,it does not require mitochondria.

(A) Anabolic processes,such as the synthesis of complex molecules from simpler ones,require an input of energy to form chemical bonds.
Since these processes consume energy,they are classified as endergonic reactions.
Anaerobic synthesis in bacteria involves building cellular components without the use of oxygen,which is an energy-consuming (endergonic) process.

(C) Anaerobic respiration,also known as fermentation,occurs in the absence of oxygen.
In yeast cells,pyruvic acid is converted into ethyl alcohol $(C_2H_5OH)$ and carbon dioxide $(CO_2)$ through the process of alcoholic fermentation.
Therefore,the end products of anaerobic respiration in yeast are ethyl alcohol and $CO_2$.

(C) Anaerobic respiration is a type of cellular respiration that occurs in the absence of $O_2$.
In this process,glucose is incompletely oxidized to produce energy,resulting in the formation of end products like ethanol and $CO_2$ (in yeast) or lactic acid.
Since $O_2$ is not required,it is not taken in,and $CO_2$ is released as a byproduct of the metabolic pathway.
Therefore,the correct statement is that carbon dioxide is given out.

(B) Anaerobic respiration was first studied and reported by Kostychev in $1902$.
This process involves the breakdown of glucose in the absence of oxygen to produce energy,ethanol,and carbon dioxide in organisms like yeast.

(B) During anaerobic respiration (such as alcoholic fermentation),glucose is partially broken down into ethanol and carbon dioxide.
In the process of glycolysis,$2$ molecules of $ATP$ are produced as a net gain.
Since no further $ATP$ is generated during the fermentation steps,the total net gain of energy remains $2$ molecules of $ATP$ per molecule of glucose.

(B) The correct answer is $B$. In yeast fermentation, the enzymatic reactions are as follows:
$1$. ${C_{12}}{H_{22}}{O_{11}} + {H_2}O \xrightarrow{\text{Invertase}} {C_6}{H_{12}}{O_6} (\text{Glucose}) + {C_6}{H_{12}}{O_6} (\text{Fructose})$
$2$. ${C_6}{H_{12}}{O_6} \xrightarrow{\text{Zymase}} 2{C_2}{H_5}OH + 2C{O_2} + 21 \text{ kcal energy}$
While yeast secretes Invertase to break down sucrose into glucose and fructose, the actual fermentation process (conversion of glucose to ethanol and carbon dioxide) is catalyzed by the enzyme complex known as Zymase.

(B) The process of fermentation of glucose by yeast is an anaerobic respiration process.
In this process,yeast cells break down glucose $(C_6H_{12}O_6)$ into ethyl alcohol $(C_2H_5OH)$ and carbon dioxide $(CO_2)$ in the absence of oxygen.
The chemical equation is: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + 2ATP$.
Therefore,$C_2H_5OH$ (ethyl alcohol) is the correct product listed among the options.

(C) Anaerobic respiration is a type of cellular respiration that occurs in the absence of oxygen.
In this process,glucose $(C_6H_{12}O_6)$ is incompletely broken down into ethanol $(C_2H_5OH)$ and carbon dioxide $(CO_2)$,releasing a small amount of energy.
The chemical equation for alcoholic fermentation (a type of anaerobic respiration) is: $C_6H_{12}O_6 \to 2C_2H_5OH + 2CO_2 + \text{energy}$.
Option $C$ correctly represents this process.

(D) Anaerobic respiration or fermentation is a metabolic process that converts sugar to acids,gases,or alcohol in the absence of oxygen.
In yeast,fermentation results in the production of ethanol $(C_2H_5OH)$ and carbon dioxide $(CO_2)$.
In certain bacteria and animal muscle cells,fermentation results in the production of lactic acid $(C_3H_6O_3)$.
Therefore,the products of fermentation include alcohol,lactic acid,and similar organic compounds.

(D) In the absence of oxygen,the pyruvic acid produced during glycolysis undergoes further breakdown through an anaerobic process known as fermentation.
$1$. Glycolysis occurs in the cytoplasm and produces pyruvic acid.
$2$. In anaerobic conditions (e.g.,in yeast or muscle cells),this pyruvic acid is converted into ethanol and carbon dioxide or lactic acid,respectively.
$3$. This entire process is collectively termed fermentation,which allows for the regeneration of $NAD^+$ required for glycolysis to continue.

(C) Yeast performs anaerobic respiration (fermentation) to break down glucose in the absence of oxygen.
The chemical equation for this process is: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + \text{Energy}$.
As shown in the equation, the products obtained are ethanol $(C_2H_5OH)$ and carbon dioxide $(CO_2)$.

(D) The process of respiration in the absence of $O_2$ is known as anaerobic respiration or fermentation.
$Saccharomyces$ (yeast) is a facultative anaerobe,meaning it can perform fermentation in the absence of $O_2$ to produce ethanol and $CO_2$.
$Chlorella$ is an alga,while $Solanum$ and $Saccharum$ are plants,all of which are obligate aerobes that require $O_2$ for respiration.

(A) Cyanide is a deadly poison that inhibits the activity of the cytochrome oxidase enzyme in the electron transport chain $(ETC)$.
In aerobic respiration,the $ETC$ is essential for the production of $ATP$. Since cyanide blocks this chain,aerobic respiration is inhibited.
In contrast,anaerobic respiration (fermentation) does not involve the $ETC$ or cytochrome oxidase. Therefore,it is considered a cyanide-resistant pathway.

(A) The conversion of organic compounds into simpler substances like alcohol or lactic acid by microorganisms is known as fermentation.
Specifically,in certain microorganisms like yeast,pyruvic acid is converted into ethanol and $CO_2$.
While lactic acid fermentation produces lactic acid,the broader biochemical process involving the anaerobic breakdown of substrates into products like alcohol is classified under fermentation.

(B) The correct answer is $B$.
Extinction point is defined as the specific concentration of oxygen at which the rate of anaerobic respiration becomes zero and the rate of aerobic respiration is at its optimum.
At this point,the $RQ$ (Respiratory Quotient) value reaches unity $(1.0)$.
For most plant tissues,this extinction point occurs at approximately $2\%\, O_2$ concentration.

(A) Fermentation is an anaerobic process in which microorganisms like yeast break down sugars (specifically glucose) into ethanol and carbon dioxide.
In this process, the chemical reaction is: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + \text{Energy}$.
Therefore, alcohol is formed from sugars.

(A) In the process of alcoholic fermentation,pyruvic acid is first decarboxylated to acetaldehyde and $CO_2$ in the presence of the enzyme pyruvic acid decarboxylase and the cofactor $TPP$ (Thiamine Pyrophosphate).
Subsequently,acetaldehyde is reduced to ethyl alcohol by the enzyme alcohol dehydrogenase using $NADH + H^+$.
Since the question specifically mentions the transformation of pyruvic acid in the presence of $TPP$ and carboxylase,the immediate products are acetaldehyde and $CO_2$.

(B) Fermentation is an anaerobic process where microorganisms like yeast break down sugars in the absence of oxygen.
In alcoholic fermentation, the chemical reaction is: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + \text{Energy}$.
As shown in the equation, $CO_2$ gas is released as a byproduct.
When this process occurs in a closed vessel, the accumulation of $CO_2$ gas leads to an increase in the internal gas pressure of the vessel.

(B) In alcohol fermentation,glucose is broken down into $2$ molecules of pyruvic acid through glycolysis,producing $NADH + H^+$.
In the subsequent steps,pyruvic acid is converted into acetaldehyde,which then acts as the final electron acceptor.
Acetaldehyde accepts electrons from $NADH + H^+$ (which originated from the oxidation of triose phosphate) to be reduced into ethanol.
Therefore,triose phosphate acts as the electron donor (indirectly via $NADH$) and acetaldehyde acts as the electron acceptor.

(C) In anaerobic respiration (fermentation),one molecule of glucose undergoes glycolysis to produce a net gain of $2$ $ATP$ molecules.
To produce $38$ $ATP$ molecules under anaerobic conditions,the number of glucose molecules required is calculated as:
$\text{Number of glucose molecules} = \frac{\text{Total ATP required}}{\text{ATP produced per glucose}} = \frac{38}{2} = 19$.
Therefore,$19$ glucose molecules are required.

(C) In animals,anaerobic respiration occurs in muscle cells during intense physical activity when oxygen supply is insufficient. In this process,glucose is incompletely broken down into lactic acid,and a small amount of energy is released. Therefore,the correct product is lactic acid.

(B) The primitive atmosphere of the Earth was reducing and lacked free molecular oxygen $(O_2)$.
Therefore,the earliest living organisms had to rely on anaerobic respiration to generate energy from organic molecules.
Aerobic respiration evolved much later after the accumulation of oxygen in the atmosphere due to the activity of photosynthetic organisms like cyanobacteria.

(D) Anaerobic respiration is a process that occurs in the absence of oxygen.
$Glycolysis$ (also known as the $EMP$ pathway) is the first step of both aerobic and anaerobic respiration.
Sugar acid fermentation is a type of anaerobic process.
The $CA$ cycle,also known as the $Citric$ $Acid$ cycle or $Krebs$ cycle,occurs only in the presence of oxygen within the mitochondrial matrix.
Therefore,the $CA$ cycle does not apply to anaerobic respiration.

(D) Anaerobic respiration is a type of cellular respiration that occurs in the absence of oxygen.
During this process,glucose is incompletely oxidized to produce energy,ethanol,and carbon dioxide (in yeast) or lactic acid (in muscle cells).
Since carbon dioxide is a byproduct of this metabolic pathway,it is released or given out by the organism.

(C) Oxygen debt refers to the extra amount of oxygen required by the body after intense exercise to restore metabolic conditions to the resting state.
During strenuous exercise,the demand for $ATP$ exceeds the rate of aerobic respiration,leading to anaerobic glycolysis in muscles,which produces lactic acid.
After exercise,this accumulated lactic acid must be transported to the liver,where it is converted back into glucose or glycogen,a process that requires oxygen.
Therefore,the accumulation of oxygen debt is evidence that lactic acid produced during anaerobic activity can be converted back into glycogen in the presence of oxygen.

(A) In anaerobic respiration,pyruvate undergoes two types of incomplete reduction.
In one case,it results in the production of ethyl alcohol (in yeast).
In the other case,it produces lactic acid (in muscle cells).
Therefore,in muscle cells,pyruvic acid is reduced to lactic acid by the enzyme lactate dehydrogenase.

(A) In anaerobic respiration (fermentation),glucose undergoes glycolysis in the cytoplasm.
Glycolysis produces a net gain of $2$ $ATP$ molecules per glucose molecule.
Since there is no further oxidation of pyruvate in the absence of oxygen,no additional $ATP$ is produced.
Therefore,the net gain of $ATP$ molecules in anaerobic respiration is $2$.

(D) During strenuous exercise,the demand for $ATP$ in muscle cells increases significantly.
When the oxygen supply is insufficient to meet this demand through aerobic respiration,muscle cells switch to anaerobic respiration.
In this process,the pyruvic acid produced via glycolysis is reduced to lactic acid by the enzyme lactate dehydrogenase.
This allows for the regeneration of $NAD^+$ from $NADH$,enabling glycolysis to continue and provide a small amount of $ATP$ to the working muscles.

(D) The correct answer is $D$.
$Tapeworms$ (e.g.,$Taenia$ $solium$) are endoparasites that live in the intestine of the host.
In this environment,oxygen is either absent or available in extremely low concentrations.
Therefore,$tapeworms$ have adapted to perform anaerobic respiration (anoxybiosis) to produce energy in the absence of oxygen.

(B) During intensive exercise,the demand for $O_2$ by the muscles exceeds the rate at which it can be supplied by the respiratory and circulatory systems.
To meet this energy demand,muscles perform anaerobic respiration,leading to the accumulation of lactic acid.
After exercise,the body continues to consume extra $O_2$ to metabolize the accumulated lactic acid and restore energy stores (like $ATP$ and creatine phosphate).
This additional amount of $O_2$ required by the body to return to the resting state is known as an $O_2$ debt.

(A) The process of sugar fermentation is a type of anaerobic respiration.
In anaerobic respiration,glucose is incompletely degraded into lactic acid (in some bacteria and muscle fibers) or into ethyl alcohol and $CO_2$ (in yeast cells).
This biochemical pathway is chemically similar to the fermentation process observed in sugar.

(B) During an all-out sprint,the body relies primarily on anaerobic respiration because the demand for $ATP$ exceeds the rate at which aerobic respiration can supply it.
This leads to the rapid breakdown of glucose into lactic acid via the anaerobic pathway.
The accumulation of lactic acid in the muscle fibers causes a decrease in $pH$,which interferes with muscle contraction and leads to muscle fatigue.
Consequently,the body cannot sustain such high-intensity activity for more than approximately $40$ seconds.