Mix Examples- Respiration in Plants Questions in English

(C) Turgidity is a property of living cells that possess a cell wall and a central vacuole,allowing them to maintain internal turgor pressure.
$A$. $Xylem$ vessels are dead cells at maturity and lack protoplasm,so they cannot exhibit turgidity.
$B$. $Xylem$ tracheids are also dead cells at maturity and lack protoplasm,so they cannot exhibit turgidity.
$C$. $Sieve$ tubes are living cells that retain their protoplasm (though they lack a nucleus) and are capable of maintaining turgor pressure,which is essential for the translocation of food.
Therefore,only $Sieve$ tubes can show turgidity.

(C) Mycotoplasm is a term used to describe the functional system within the sieve tube elements of the phloem.
It consists of the cytoplasm and the vacuolar system of the sieve tube,in which water and food materials (sucrose) are suspended and transported.

(C) In monocot plants like sugarcane and maize,the vascular bundles are scattered throughout the stem and are closed (lacking cambium).
Because they lack cambium,they do not exhibit secondary growth.
Therefore,it is impossible to isolate the phloem by removing a ring of bark (as the bark does not exist in the same way as in dicots),making the girdling experiment ineffective.

(B) The correct statement is that plants take in small quantities of mineral salts through soil water.
While the soil contains a wide variety of mineral elements,not all of them are essential for plant growth.
Plants selectively absorb these minerals in small amounts along with water to support their physiological processes and growth.

(C) Water absorption occurs most efficiently in well-aerated soil.
When soil is water-logged,the air spaces are filled with water,leading to a deficiency of $O_2$.
This lack of $O_2$ inhibits the aerobic respiration of root cells.
As a result,$CO_2$ accumulates in the roots,causing the protoplasm to become viscous and reducing the permeability of the plasma membrane.
These physiological changes significantly decrease the rate of water and mineral absorption,eventually leading to the death of the plant.

(D) Transpiration is the process of water movement through a plant and its evaporation from aerial parts,such as leaves,stems,and flowers.
On a large scale,forests contribute significantly to the atmospheric moisture content through transpiration.
This released water vapor influences local humidity,cloud formation,and rainfall patterns.
Consequently,transpiration plays a crucial role in regulating the temperature and rainfall conditions within terrestrial habitats.

(D) Respiration is a fundamental metabolic process that provides energy in the form of $ATP$ for various cellular activities.
$1$. Cell division requires significant amounts of energy to synthesize new cellular components and replicate $DNA$.
$2$. The conversion of complex,insoluble food materials into simpler,soluble forms often requires energy-dependent enzymatic processes.
$3$. Respiration releases $CO_2$ back into the atmosphere,which is a critical component of the carbon cycle,helping to maintain the balance of atmospheric gases.
Therefore,respiration is essential for all the listed processes.

(B) The correct answer is $B$.
In a seed godown,seeds are stored in large quantities.
These seeds continue to respire,and due to the high density of seeds and limited ventilation,the oxygen concentration decreases while the carbon dioxide $(CO_2)$ concentration increases significantly.
High levels of $CO_2$ and low levels of oxygen lead to a feeling of suffocation for a person entering the godown.

(A) The correct answer is $A$.
Photosynthesis is an anabolic process where light energy is used to synthesize glucose from $CO_2$ and $H_2O$,releasing $O_2$ as a byproduct.
Respiration is a catabolic process where glucose is oxidized to release energy,consuming $O_2$ and producing $CO_2$ and $H_2O$.
Therefore,respiration is considered the reverse of photosynthesis.

(A) Respiration is a catabolic process in which complex organic molecules like glucose are broken down into simpler substances like $CO_2$ and $H_2O$.
Since the substrate (e.g.,glucose) is consumed and converted into gaseous $CO_2$ which is released into the atmosphere,there is a net loss of dry weight in the organism during the process of respiration.

(D) Phosphorylation is the addition of a phosphate group to a molecule.
$1$. In Glycolysis: Glucose is phosphorylated to Glucose$-6-$phosphate.
$2$. In Krebs cycle: Substrate-level phosphorylation occurs when Succinyl-CoA is converted to Succinate,forming $GTP$/$ATP$.
$3$. In $HMP$ pathway: It also involves phosphorylated sugars like Glucose$-6-$phosphate.
Therefore,phosphorylation takes place in all of the above.

(A) The correct matches are as follows:
$1$. $A$. Kreb's cycle occurs in the mitochondrial matrix $(iv)$.
$2$. $B$. Photorespiration occurs in peroxisomes $(iii)$.
$3$. $C$. Oxidative phosphorylation occurs on the inner mitochondrial membrane, specifically at the stalked particles or $F_0-F_1$ complexes $(i)$.
$4$. $D$. Glycolysis occurs in the cytoplasm $(ii)$.
Therefore, the correct sequence is $A-iv, B-iii, C-i, D-ii$.

(D) The correct matches are as follows:
$A$. $PPP$ (Pentose Phosphate Pathway) is also known as the $iii$. Warburg-Dickens pathway.
$B$. The demonstration of fermentation is associated with $i$. Kuhne.
$C$. The $TCA$ cycle (Tricarboxylic Acid cycle) was discovered by $ii$. Hans Krebs.
$D$. Glycolysis is also known as the $iv$. Embden-Meyerhof-Parnas $(EMP)$ pathway.
Therefore, the correct sequence is $A-iii, B-i, C-ii, D-iv$.

(B) In aerobic respiration,although other substances like fats,proteins,and organic acids can be used as respiratory substrates,glucose is the most preferred substrate. This is because glucose is a simple sugar that can be easily broken down through glycolysis to enter the respiratory pathway,providing immediate energy to the cell.

(D) The rate of respiration can be inhibited by various chemical substances:
$1$. $Malonate$ acts as a competitive inhibitor of the enzyme succinate dehydrogenase in the Krebs cycle.
$2$. High concentrations of $CO_2$ can inhibit respiration through feedback mechanisms or by affecting the pH of the cellular environment.
$3$. $Chloroform$ and $cyanides$ are potent metabolic inhibitors. Specifically,$cyanide$ binds to cytochrome c oxidase in the electron transport chain,effectively blocking aerobic respiration.
Therefore,all the listed substances can check or inhibit the rate of respiration.

(B) Respiration is the process of breaking down respiratory substrates like glucose to release energy in the form of $ATP$.
In a starved plant,the availability of respiratory substrates is very low,which limits the rate of respiration.
When glucose is provided to such a plant,it acts as an immediate respiratory substrate.
As the concentration of the substrate increases,the enzymes involved in glycolysis and the Krebs cycle can catalyze the reactions more efficiently,leading to an increase in the rate of respiration.

(A) During the process of photosynthesis,the radiant energy of the sun is converted into potential chemical energy stored in organic compounds (food).
During the process of respiration,this stored potential energy is released to perform biological work,primarily in the form of kinetic energy (used for cellular activities) and heat energy.
Therefore,the correct answer is kinetic energy.

(D) Respiration is a fundamental metabolic process in plants that involves the breakdown of respiratory substrates (like glucose) to release energy in the form of $ATP$.
$1$. It provides energy for various cellular activities,growth,and development.
$2$. It releases $CO_2$ as a byproduct,which is essential for maintaining the carbon cycle.
$3$. While plants produce oxygen during photosynthesis,respiration is the process that utilizes oxygen to oxidize food materials.
Therefore,all the listed options describe aspects or consequences of the respiratory process in plants.

(D) Heat energy,whether in plants or other biological systems,is a form of energy released during metabolic processes like respiration. The standard unit used to measure heat energy is the $Calorie$ (or $Joule$). Among the given options,$Calories$ is the correct unit for measuring heat energy.

(B) The correct pairing is as follows:
$1$. Glycolysis $(A)$ occurs in the cytoplasm of the cell,which is the cytoplasmic matrix $(b)$.
$2$. Kreb's cycle $(B)$ occurs in the matrix of the mitochondria $(a)$.
$3$. The Electron transport chain $(C)$ is located on the inner mitochondrial membrane,which is part of the mitochondria $(a)$.
Therefore,the correct matching is $A-b, B-a, C-a$.

(D) In aerobic respiration,substrate-level phosphorylation occurs at the following steps:
$1$. During Glycolysis: $2$ molecules of $ATP$ are produced (conversion of $1,3$-bisphosphoglycerate to $3$-phosphoglycerate and phosphoenolpyruvate to pyruvate).
$2$. During the Krebs cycle (Citric Acid Cycle): $2$ molecules of $GTP$ (which are equivalent to $ATP$) are produced per glucose molecule (one per turn of the cycle,as two acetyl-CoA enter the cycle).
Therefore,the total number of $ATP$ molecules produced via substrate-level phosphorylation is $2 + 2 = 4$.

(A) Ganong's respiroscope is a laboratory apparatus specifically designed to demonstrate the process of aerobic respiration in germinating seeds.
It works on the principle that during aerobic respiration,seeds consume oxygen and release carbon dioxide.
The apparatus consists of a bulb containing germinating seeds connected to a tube containing a potassium hydroxide $(KOH)$ solution.
As the seeds respire,they absorb oxygen,and the $CO_2$ produced is absorbed by the $KOH$ solution,creating a partial vacuum that causes the level of the liquid in the tube to rise,thereby demonstrating the consumption of oxygen and the release of $CO_2$.

(B) Dehydrogenation is a chemical reaction that involves the removal of hydrogen from an organic molecule.
Since a hydrogen atom consists of one proton and one electron,the removal of two hydrogen atoms $(2H)$ is equivalent to the loss of two protons $(2H^+)$ and two electrons $(2e^-)$.
This process is a fundamental step in cellular respiration,particularly in the Krebs cycle and glycolysis,where enzymes called dehydrogenases facilitate the transfer of these electrons to coenzymes like $NAD^+$ and $FAD$.

(B) Decarboxylation is the process of removing a carboxyl group from a compound,usually releasing $CO_2$.
In $Glycolysis$,glucose $(6C)$ is broken down into two molecules of pyruvate $(3C)$. There is no loss of carbon atoms in this pathway,so decarboxylation does not occur.
In $Kreb's \text{ cycle}$,decarboxylation occurs at two steps (isocitrate to $\alpha$-ketoglutarate and $\alpha$-ketoglutarate to succinyl-$CoA$).
In $Alcoholic \text{ fermentation}$,pyruvate is converted to acetaldehyde and then to ethanol,releasing $CO_2$ during the first step.
In the $Electron \text{ transport system}$,the process involves redox reactions and oxidative phosphorylation,not decarboxylation.

(C) The correct answer is $C$. In aerobic respiration,$CO_2$ is released at $3$ distinct steps during the oxidation of one molecule of pyruvic acid:
$(i)$ During the conversion of pyruvic acid to acetyl $CoA$ (Link reaction).
(ii) During the conversion of isocitric acid to $\alpha$-ketoglutaric acid in the Krebs cycle.
(iii) During the conversion of $\alpha$-ketoglutaric acid to succinyl $CoA$ in the Krebs cycle.

(B) The hexose monophosphate $(HMP)$ shunt is an alternative pathway for glucose oxidation,which is also known as the pentose phosphate pathway or the $HMS$ $(Hexose Monophosphate Shunt)$ pathway.
$EMP$ pathway refers to glycolysis.
$TCA$ cycle and Citric acid cycle are synonymous terms for the Krebs cycle.

(C) The direct oxidation pathway,also known as the Pentose Phosphate Pathway $(PPP)$ or Hexose Monophosphate Shunt,involves the oxidation of glucose$-6-$phosphate.
In this pathway,the complete oxidation of one hexose molecule results in the production of $12 \,NADPH$ molecules.
Since each $NADPH$ molecule is equivalent to $3 \,ATP$ molecules in terms of energy yield,the total production is $12 \times 3 = 36 \,ATP$ molecules.

(C) The $HMP$ (Hexose Monophosphate) shunt,also known as the pentose phosphate pathway,is an alternative metabolic pathway for glucose oxidation.
It operates parallel to the $EMP$ (Embden-Meyerhof-Parnas) pathway,which is the standard glycolysis route.
Therefore,both statements $A$ and $B$ are correct descriptions of the $HMP$ shunt.

(B) The Pentose Phosphate Pathway $(PPP)$,also known as the Hexose Monophosphate $(HMP)$ shunt,is an alternative metabolic pathway to glycolysis for the oxidation of glucose.
This pathway was elucidated by Otto Warburg in $1935$ and Frank Dickens in $1938$.
Therefore,the correct option is $B$.

(C) In the process of glycolysis,there is no evolution of $CO_2$ molecules. Glycolysis involves the breakdown of glucose into two molecules of pyruvate without the release of carbon dioxide. In contrast,the hexose monophosphate $(HMP)$ shunt,also known as the pentose phosphate pathway,involves the oxidative decarboxylation of glucose$-6-$phosphate,which results in the release of $CO_2$ molecules. Therefore,the number of $CO_2$ molecules evolved in the $HMP$ shunt is more than in glycolysis.

(A) The correct answer is $A$.
During injury and infection,the damaged cells produce a hormone called traumatin.
Traumatin stimulates the rate of cell division in the surrounding tissues to repair the injury.
Cell division is an energy-intensive process that requires significant amounts of $ATP$.
To meet this increased energy demand,the rate of cellular respiration increases,which leads to an increase in the rate of $O_2$ consumption.

(A) The rate of respiration increases when a plant or tissue is transferred from water to a dilute salt solution.
This phenomenon is known as salt respiration or induced respiration.
The increase in respiration occurs because the plant cells require additional energy in the form of $ATP$ to perform the active absorption of mineral ions from the salt solution against the concentration gradient.

(B) The rate of aerobic respiration is directly dependent on the concentration of oxygen available in the environment.
When oxygen levels drop significantly,such as to $1\%$,the aerobic respiration process is severely inhibited because oxygen acts as the final electron acceptor in the electron transport chain.
Consequently,at such low concentrations,the rate of respiration decreases to its minimum level,as the cell may shift towards anaerobic pathways or simply slow down metabolic activity due to the lack of sufficient oxygen.

(B) The correct answer is $(b)$.
High concentrations of $CO_2$ act as an inhibitor for the process of respiration.
According to the law of mass action,an increase in the concentration of the product $(CO_2)$ shifts the equilibrium of the respiratory reactions backward,thereby decreasing the overall rate of respiration.

(C) During seed germination,the embryo undergoes active respiration to provide energy for growth. Respiration is an exothermic process,meaning it releases energy in the form of heat. This heat production can be experimentally demonstrated using a thermos flask containing germinating seeds,where a thermometer shows a rise in temperature.

(A) Carbohydrates are primarily broken down through cellular respiration (glycolysis,the Krebs cycle,and the electron transport chain).
During this process,glucose is oxidized to produce energy in the form of $ATP$.
The final byproducts of aerobic respiration of carbohydrates are carbon dioxide $(CO_2)$ and water $(H_2O)$.

(C) Mammals obtain water through two primary sources: ingestion (drinking) and metabolic processes.
During cellular respiration, the oxidation of glucose $(C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy})$ produces metabolic water as a byproduct.
Therefore, the correct option is $C$.

(C) In cellular respiration,energy is produced in the form of $ATP$ through multiple metabolic pathways.
$1$. Glycolysis occurs in the cytoplasm and produces a net gain of $2$ $ATP$ molecules and $2$ $NADH$ molecules.
$2$. The Krebs cycle (also known as the Citric Acid Cycle) occurs in the mitochondrial matrix and produces $ATP$ (or $GTP$),$NADH$,and $FADH_2$.
Both processes are essential stages of aerobic respiration where energy is harvested from glucose.
Therefore,energy is produced during both Glycolysis and the Krebs cycle.

(C) Cellular respiration is a metabolic process of oxidation in which food materials (glucose) are oxidized to release energy. The primary byproducts or waste products of this aerobic oxidation process are $CO_2$ and water $(H_2O)$.

(C) The ketone bodies are a group of three substances produced by the liver during the metabolism of fatty acids.
These include $Acetone$, $Acetoacetate$ (Acetoacetic acid), and $D$-$\beta$-hydroxybutyrate ($\beta$-hydroxybutyric acid).
$Succinic$ $acid$ is an intermediate of the $Krebs$ cycle and is not classified as a ketone body.
Therefore, the correct option is $C$.

(B) The Cori cycle,also known as the lactic acid cycle,involves the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles is transported to the liver. In the liver,lactate is converted back to glucose through gluconeogenesis. This glucose is then released back into the blood and returned to the muscles to be used as an energy source. Thus,the cycle operates between the liver and the muscles.

(D) The $HMP$ shunt,also known as the Pentose Phosphate Pathway $(PPP)$,is a metabolic pathway that runs parallel to glycolysis ($EMP$ pathway).
In this pathway,glucose-$6$-phosphate is oxidized to produce $NADPH_2$ (or $NADPH$),which serves as a crucial reducing agent for biosynthetic reactions and fatty acid synthesis.
Unlike the $EMP$ pathway or the Krebs cycle,which primarily focus on $ATP$ production and $NADH/FADH_2$ generation,the $HMP$ shunt is specifically characterized by the production of $NADPH_2$ and pentose sugars.

(A) The pentose phosphate pathway $(PPP)$,also known as the hexose monophosphate $(HMP)$ shunt,begins with the oxidation of glucose-$6$-phosphate.
In the first step,glucose-$6$-phosphate is converted into $6$-phosphogluconolactone by the enzyme glucose-$6$-phosphate dehydrogenase.
This reaction involves the reduction of $NADP^+$ to $NADPH$.
Therefore,the initial step is the oxidation of glucose-$6$-phosphate.

(B) The $HMP$ shunt (Hexose Monophosphate Shunt),also known as the Pentose Phosphate Pathway $(PPP)$,is a metabolic pathway parallel to glycolysis.
In this pathway,glucose-$6$-phosphate is oxidized to produce $NADPH$ (often represented as $NADP·H_2$).
$NADPH$ serves as a crucial reducing agent for biosynthetic reactions in the cell.
Therefore,the reduction of $NADP$ to $NADP·H_2$ is primarily associated with the $HMP$ shunt.

(D) The Krebs cycle,also known as the Citric Acid Cycle,serves two primary purposes:
$1$. It is the main pathway for the oxidation of acetyl-$CoA$ to produce $ATP$ (via $NADH$ and $FADH_2$ in the electron transport chain).
$2$. It acts as an amphibolic pathway,providing intermediates for the biosynthesis of various molecules,including amino acids (e.g.,$\alpha$-ketoglutarate and oxaloacetate are precursors for glutamate and aspartate) and other cellular components like porphyrins (which are precursors for chlorophyll).
Therefore,all the listed options are correct.

(A) Respiration is a catabolic process that involves the breakdown of complex organic molecules like glucose to release energy in the form of $ATP$.
During this process,the stored energy in chemical bonds is converted into a usable form.
As a result of this energy release,the organism can perform various metabolic activities,which leads to growth and an increase in the size of the organism.
Therefore,respiration is fundamentally linked to the growth and increase in size of living cells.

(C) Aerobic respiration is the process of complete oxidation of glucose in the presence of oxygen.
The chemical equation for aerobic respiration is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$.
The total energy released during the complete oxidation of one mole of glucose is approximately $686 \ kcal$ (or $2870 \ kJ$).

(A) The aerobic oxidation of one molecule of pyruvate involves the link reaction and the Krebs cycle.
$1$. Link reaction: $1$ Pyruvate + $1$ CoA + $1$ $NAD^+$ $\rightarrow$ $1$ Acetyl-CoA + $1$ $NADH$ + $1$ $CO_2$.
$2$. Krebs cycle: $1$ Acetyl-CoA + $3$ $NAD^+$ + $1$ $FAD$ + $1$ $GDP$ + $1$ $Pi$ + $2$ $H_2O$ $\rightarrow$ $2$ $CO_2$ + $3$ $NADH$ + $1$ $FADH_2$ + $1$ $GTP$ + $1$ CoA.
Total $NADH$ produced = $1$ (link) + $3$ (Krebs) = $4$ $NADH$.
Total $FADH_2$ produced = $1$ $FADH_2$.
In the Electron Transport System $(ETS)$,the oxidation of $1$ $NADH$ requires $0.5$ $O_2$ and $1$ $FADH_2$ requires $0.5$ $O_2$.
Total $O_2$ required = $(4 \times 0.5) + (1 \times 0.5) = 2 + 0.5 = 2.5$ molecules of $O_2$ per pyruvate.
The balanced equation for the complete oxidation of pyruvate is: $CH_3COCOOH + 2.5 O_2 \rightarrow 3 CO_2 + 2 H_2O$. Thus,$2.5$ molecules of $O_2$ are required.

(D) Respiration is a fundamental metabolic process in all living organisms.
$1$. Its primary purpose is the breakdown of respiratory substrates (like glucose) to release energy in the form of $ATP$.
$2$. During this process,$CO_2$ is produced as a byproduct and is released from the body.
$3$. In plants,while they perform photosynthesis to produce oxygen,respiration is essential for energy production,which occurs continuously.
Therefore,all the given options describe aspects or consequences of the respiratory process.

(B) The balanced chemical equation for aerobic respiration is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + 686 \ kcal$ energy.
$1$. Molar mass of glucose $(C_6H_{12}O_6)$ = $(6 \times 12) + (12 \times 1) + (6 \times 16) = 72 + 12 + 96 = 180 \ g/mol$.
$2$. Molar mass of $6O_2$ = $6 \times (2 \times 16) = 6 \times 32 = 192 \ g$.
$3$. According to the equation,$180 \ g$ of glucose reacts with $192 \ g$ of oxygen to produce:
- $6 \times CO_2$ = $6 \times (12 + 32) = 6 \times 44 = 264 \ g$.
- $6 \times H_2O$ = $6 \times (2 + 16) = 6 \times 18 = 108 \ g$.
- Energy released = $686 \ kcal$.
Therefore,the correct option is $B$.