Mitochondria Questions in English

(C) The electron transport system $(ETS)$ is located in the inner mitochondrial membrane.
When mitochondria are disrupted,the inner membrane breaks into smaller vesicles called submitochondrial particles or $F_1-F_0$ particles.
These fragments retain the structural integrity of the electron transport chain and the $ATP$ synthase complex.
Because these fragments are still capable of synthesizing $ATP$ in the presence of substrates and oxygen,it provides strong evidence that the enzymes involved in electron transfer and oxidative phosphorylation are organized into compact,functional associations within the membrane.

(C) The process of cellular respiration occurs within the cell to produce energy in the form of $ATP$.
$Mitochondria$ are known as the 'powerhouse of the cell' because they are the primary sites where aerobic respiration takes place, converting glucose and oxygen into energy $(ATP)$ through the $Krebs$ cycle and the electron transport chain.

(D) Mitochondria are known as the powerhouses of the cell.
They are the sites of aerobic respiration,where the oxidation of respiratory substrates (like glucose) occurs to produce energy in the form of $ATP$ (Adenosine Triphosphate).
This process is known as oxidative phosphorylation.

(C) Cellular respiration is a metabolic process that occurs in the cell to produce energy in the form of $ATP$. The primary site for aerobic cellular respiration,specifically the Krebs cycle and electron transport chain,is the mitochondria. Therefore,mitochondria are often referred to as the 'powerhouse of the cell'.

(C) Janus green-$B$ is a vital stain used to identify mitochondria in living cells.
It is a basic dye that specifically stains mitochondria blue-green because of the presence of cytochrome oxidase,which keeps the dye in its oxidized (colored) state within the mitochondria,while it remains colorless in the cytoplasm.

(D) During the process of oxidative phosphorylation in mitochondria,the electron transport system $(ETS)$ is located in the inner mitochondrial membrane.
As electrons pass through the complexes of the $ETS$,energy is released and used to pump protons $(H^+)$ from the mitochondrial matrix into the intermembrane space.
This creates a high concentration of protons in the intermembrane space,establishing a proton gradient (electrochemical gradient) across the inner mitochondrial membrane.
This gradient drives the synthesis of $ATP$ through the enzyme $ATP$ synthase.

(C) Mitochondria are known as the '$powerhouse$ of the cell'.
They are the primary sites for aerobic respiration,where the process of oxidative phosphorylation occurs.
During this process,nutrients like glucose are broken down to release energy in the form of $ATP$ (Adenosine Triphosphate).
Therefore,mitochondria are the sites for energy release during respiration.

(C) The oxidative process of cellular respiration,specifically the Krebs cycle and the electron transport chain,occurs within the mitochondria. Mitochondria are often referred to as the 'powerhouse of the cell' because they generate most of the cell's supply of adenosine triphosphate $(ATP)$,which is used as a source of chemical energy.

(D) The correct answer is $D$.
$1$. The inner mitochondrial membrane is highly folded into structures called cristae,which increase the surface area for biochemical reactions.
$2$. The outer membrane is porous and acts like a sieve,allowing the passage of small molecules and ions.
$3$. However,the outer membrane is not permeable to all types of molecules; it is selectively permeable to proteins and larger molecules.
$4$. Most importantly,the enzymes of the electron transport chain $(ETC)$ are located in the inner mitochondrial membrane,not the outer membrane.

(B) Extranuclear $DNA$ refers to the genetic material present outside the nucleus of a eukaryotic cell.
In eukaryotic cells,$DNA$ is primarily located in the nucleus.
However,certain semi-autonomous organelles contain their own circular $DNA$ molecules,which are independent of the nuclear genome.
These organelles are the mitochondria (the powerhouses of the cell) and chloroplasts (the sites of photosynthesis in plants).
Therefore,extranuclear $DNA$ is found in chloroplasts and mitochondria.

(B) Mitochondria and chloroplasts are semi-autonomous organelles that contain their own genetic material. This genetic material is present in the form of circular,double-stranded $DNA$ molecules,which is similar to the $DNA$ found in prokaryotic cells. The $DNA$ in the nucleus is typically linear and associated with histones.

(D) Mitochondria contain their own genetic material,which is referred to as mitochondrial $DNA$ $(mtDNA)$.
$1$. It is 'naked' because it lacks associated histone proteins,unlike nuclear $DNA$.
$2$. It is 'circular' in structure,similar to prokaryotic $DNA$.
$3$. It is 'double-stranded' in nature.
Therefore,all the given statements are correct.

(C) Mitochondria are known as the power house of the cell because they produce cellular energy in the form of $ATP$ (Adenosine Triphosphate) through the process of aerobic respiration.

(A) The mitochondrial matrix is the space enclosed by the inner mitochondrial membrane. It contains a complex mixture of enzymes,including those required for the Krebs cycle (also known as the citric acid cycle or $TCA$ cycle). Additionally,the matrix contains its own circular $DNA$,$RNA$,and ribosomes,which are essential for protein synthesis within the mitochondrion.

(C) Mitochondria are double-membrane-bound organelles found in most eukaryotic organisms.
They were historically referred to as $Chondriosomes$ (from the Greek $chondrion$ meaning 'granule' and $soma$ meaning 'body') due to their granular appearance under a microscope.
Therefore,the correct term among the given options is $Chondriosomes$.

(C) The $F_1$ particle,also known as the headpiece,is a part of the $ATP\text{synthase}$ enzyme complex (also called $F_0-F_1$ complex) located on the inner mitochondrial membrane.
This complex is responsible for the synthesis of $ATP$ from $ADP$ and inorganic phosphate during oxidative phosphorylation.
The $F_1$ headpiece contains the catalytic sites for $ATP$ synthesis,while the $F_0$ portion acts as a proton channel.

(A) Mitochondria are highly variable in their size and shape. They are typically sausage-shaped or cylindrical,but their morphology can change depending on the physiological state of the cell. Furthermore,mitochondria are semi-autonomous organelles that contain their own $DNA$ and ribosomes,allowing them to replicate through binary fission.

(A) double-membrane bound organelle consists of two lipid bilayer membranes.
$1$. Mitochondria are double-membrane bound organelles involved in cellular respiration and $ATP$ production.
$2$. Ribosomes are non-membrane bound organelles.
$3$. Lysosomes are single-membrane bound organelles.
$4$. Centrioles are non-membrane bound structures.
Therefore,the correct option is $A$.

(C) Mitochondria contain their own genetic material,which is known as mitochondrial $DNA$ $(mtDNA)$.
This $DNA$ is typically circular in shape and double-stranded,similar to the $DNA$ found in prokaryotic cells.
Therefore,the correct description of mitochondrial $DNA$ is that it is double-stranded and circular.

(A) The mitochondria are double-membrane-bound structures. The inner membrane divides the lumen into two distinct aqueous compartments: the outer compartment and the inner compartment. The inner compartment is filled with a dense,homogeneous substance called the matrix. Therefore,the correct answer is $A$.

(B) The $Mitochondria$ are known as the 'powerhouse' or 'cellular furnace' of the cell.
This is because they are the sites of aerobic respiration, where $ATP$ (Adenosine Triphosphate) is produced through the oxidation of carbohydrates and fats.
Since $ATP$ provides the energy required for various cellular activities, the $Mitochondria$ are essential for the energy metabolism of the cell.

(C) Mitochondria are known as the powerhouses of the cell because they produce energy in the form of $ATP$.
This process occurs through cellular respiration,specifically the $TCA$ cycle (also known as the Krebs cycle) and the electron transport chain.
In the $TCA$ cycle,substrates like pyruvate (derived from glucose) are oxidized to release energy,which is then used to synthesize $ATP$.
Therefore,the oxidation of $TCA$ cycle substrates is the primary mechanism for energy production.

(B) Aerobic respiration is a metabolic process that occurs in the presence of oxygen to produce energy in the form of $ATP$.
$Mitochondria$ are known as the 'powerhouse of the cell' because they are the primary sites where the Krebs cycle and electron transport chain occur, facilitating aerobic respiration.
$Chloroplasts$ are involved in photosynthesis, $Ribosomes$ in protein synthesis, and the $Golgi$ $apparatus$ in packaging and secretion.

(B) Mitochondria are the sites of aerobic respiration,where $ATP$ is produced through the Krebs cycle and electron transport chain. Aerobic organisms rely entirely on this process. Facultative anaerobes can perform aerobic respiration in the presence of oxygen using mitochondria,but can switch to fermentation in the absence of oxygen. Therefore,mitochondria are present in both aerobic and facultative anaerobic organisms.

(B) Extranuclear inheritance,also known as cytoplasmic inheritance,refers to the transmission of genes that are located outside the nucleus.
In eukaryotic cells,the organelles that contain their own $DNA$ (extranuclear $DNA$) are the mitochondria and chloroplasts.
This $DNA$ is independent of the nuclear genome and is inherited through the cytoplasm,typically from the maternal parent.
Therefore,the correct option is $B$.

(A) $Janus \ Green$ is a vital stain used in histology and cytology to stain mitochondria.
It is a basic dye that acts as a redox indicator.
In its oxidized state,it is blue,and in its reduced state,it is colorless.
Since mitochondria are the sites of cellular respiration,they maintain the dye in its oxidized (blue) state,allowing them to be visualized under a microscope.

(B) $Mitochondria$ are known as the powerhouses of the cell.
They are the sites of aerobic respiration, where they produce cellular energy in the form of $ATP$ $(Adenosine \text{ } Triphosphate)$ through the process of oxidative phosphorylation.
Therefore, the primary function of $Mitochondria$ is cellular respiration.

(B) In an animal cell,the nucleus is the largest cell organelle. However,among the options provided,the mitochondrion is the largest. Plastids are absent in animal cells. Lysosomes and Golgi apparatus are smaller than mitochondria in terms of overall volume and structural prominence in most animal cells.

(A) Mitochondria are membrane-bound cell organelles found in the cytoplasm of eukaryotic cells. They are known as the 'powerhouse of the cell' because they generate most of the cell's supply of adenosine triphosphate $(ATP)$,used as a source of chemical energy. Prokaryotic cells,plasmids,prions,and viruses lack mitochondria.

(D) $ATP$ (Adenosine Triphosphate) is known as the energy currency of the cell.
It is a nucleotide that stores and transfers energy within cells to drive various biological processes.
When the cell needs energy,it breaks down $ATP$ into $ADP$ (Adenosine Diphosphate) and an inorganic phosphate,releasing energy in the process.

(D) Mitochondria are membrane-bound cell organelles that are essential for aerobic respiration and the production of $ATP$ (adenosine triphosphate).
They are present in almost all eukaryotic cells,including both plants and animals.
They are absent in prokaryotic cells (like bacteria) and mature mammalian red blood cells $(RBCs)$.

(B) The inner mitochondrial membrane forms infoldings known as cristae.
These cristae significantly increase the surface area of the inner membrane.
Attached to the cristae are numerous stalked particles known as $F_0-F_1$ particles or oxysomes.
These $F_1$ particles are the sites of $ATP$ synthesis via oxidative phosphorylation.

(A) According to the $NCERT$ textbook,mitochondria are sausage-shaped or cylindrical structures having a diameter of $0.2 - 1.0 \mu m$ (average $0.5 \mu m$) and a length of $1.0 - 4.1 \mu m$. Therefore,the correct option is $A$.

(C) Mitochondria and chloroplasts are considered semi-autonomous or self-replicating organelles because they contain their own circular $DNA$ and ribosomes $(70S)$,which allow them to synthesize some of their own proteins and replicate independently of the cell cycle. Therefore,the correct option is $C$.

(A) Mitochondria are known as the powerhouse of the cell because they generate most of the cell's supply of adenosine triphosphate $(ATP)$,which is used as a source of chemical energy.
The $Krebs$ cycle (citric acid cycle) occurs in the mitochondrial matrix,and the electron transport chain (leading to oxidative phosphorylation) occurs on the inner mitochondrial membrane.
Since these processes are responsible for the production of $ATP$ through cellular respiration,the reason $R$ correctly explains why mitochondria are called the powerhouse of the cell.

(A) The mitochondria consist of an outer membrane and an inner membrane. The inner membrane is folded into a number of infoldings called $Cristae$ towards the matrix. These $Cristae$ increase the surface area of the inner membrane,which is essential for the attachment of enzymes involved in the electron transport chain and $ATP$ synthesis.

(C) Mitochondria and chloroplasts are known as semi-autonomous organelles because they contain their own circular $DNA$ and $70S$ ribosomes,which allow them to synthesize some of their own proteins and replicate independently of the cell cycle. Therefore,they are referred to as self-replicating organelles.

(A) Mitochondria are known as the powerhouses of the cell because they generate $ATP$ through cellular respiration.
Their number per cell is highly variable and depends on the metabolic activity of the cell.
Cells that require more energy,such as muscle cells or liver cells,contain a significantly higher number of mitochondria compared to cells with lower energy demands.
Therefore,the metabolic activity of the cell determines the mitochondrial count.

(A) Mitochondria are membrane-bound cell organelles.
They are typically sausage-shaped or cylindrical,having a diameter of $0.2-1.0 \mu m$ (average $0.5 \mu m$) and a length of $1.0-4.1 \mu m$.
Depending on the physiological activity of the cell,their shape can vary,appearing as filamentous,granular,or cylindrical structures.

(B) According to the $NCERT$ textbook,the diameter of the mitochondrion is $0.2 \, \mu m - 1.0 \, \mu m$ (average $0.5 \, \mu m$) and its length is $1.0 \, \mu m - 4.1 \, \mu m$. Therefore,the correct option is $B$.

(A) According to the $NCERT$ textbook,mitochondria are sausage-shaped or cylindrical structures having a diameter of $0.2 \, \mu m - 1.0 \, \mu m$ (average $0.5 \, \mu m$) and a length of $1.0 \, \mu m - 4.1 \, \mu m$.

(C) The mitochondria consist of an outer membrane and an inner membrane. The inner membrane forms a number of infoldings called $Cristae$ towards the matrix. These infoldings increase the surface area of the inner membrane,which is essential for the attachment of enzymes involved in the electron transport chain and $ATP$ synthesis.

(C) The mitochondria is a double-membrane-bound organelle. The inner membrane forms infoldings called cristae towards the matrix. The space enclosed by the inner membrane is called the matrix. The matrix contains a single circular $DNA$ molecule,a few $RNA$ molecules,ribosomes $(70S)$,and the enzymes required for the synthesis of proteins.

(C) Mitochondria are double-membrane-bound organelles.
Option $A$ is correct as the inner membrane forms infoldings called cristae,which bear '$F_1$ particles' ($ATP$ synthase).
Option $B$ is correct as these infoldings are indeed called cristae.
Option $D$ is correct as the dimensions of mitochondria typically range from $0.2$ to $1.0 \mu m$ in diameter and $1.0$ to $4.1 \mu m$ in length.
Option $C$ is incorrect because the fluid-filled space inside mitochondria is called the 'matrix',not the 'stroma'. The term 'stroma' is specifically used for the fluid-filled space inside chloroplasts.

(A) The mitochondria contain a system of folded membranes known as cristae. These folds increase the surface area of the inner mitochondrial membrane,which is essential for the electron transport chain and $ATP$ synthesis during cellular respiration.

(C) $F_1$ particles (also known as $F_0-F_1$ complex or $ATP$ synthase) are located on the inner mitochondrial membrane and are responsible for $ATP$ synthesis via oxidative phosphorylation. Thus,statement $S$ is true.
Glycolysis occurs in the cytoplasm of the cell,not in the mitochondrial matrix. The mitochondrial matrix contains enzymes for the Krebs cycle ($TCA$ cycle) and fatty acid oxidation. Thus,statement $R$ is false.
Therefore,$S$ is true and $R$ is false.

(D) According to the $NCERT$ textbook,the dimensions of cell organelles are as follows:
$1$. Mitochondria are typically sausage-shaped or cylindrical,having a diameter of $0.2 \mu m$ to $1.0 \mu m$ (average $0.5 \mu m$) and a length of $1.0 \mu m$ to $4.1 \mu m$.
$2$. Option $D$ states the length of mitochondria as $1 \mu m$ to $5.1 \mu m$,which is the closest and most accurate representation of the standard biological data provided in the curriculum.
$3$. Other options contain incorrect units or values for the specified organelles.

(A) The figure shows a mitochondrion. The part labeled 'a' points to the inner mitochondrial membrane (cristae). The Krebs cycle occurs in the mitochondrial matrix,while oxidative phosphorylation takes place on the inner mitochondrial membrane. Therefore,the correct process occurring at the site labeled 'a' is oxidative phosphorylation.

(B) Cellular respiration is the process by which cells generate energy in the form of $ATP$ (Adenosine Triphosphate) by breaking down glucose.
$Mitochondria$ are known as the 'powerhouse of the cell' because they are the primary sites where aerobic respiration occurs.
Within the $mitochondria$, the Krebs cycle and the electron transport chain take place to produce energy.
Therefore, the correct option is $B$.

(A) The mitochondria consist of an outer membrane and an inner membrane,dividing its lumen into two distinct aqueous compartments: the outer compartment and the inner compartment. The inner membrane forms a number of infoldings called $cristae$ towards the matrix. These $cristae$ increase the surface area of the inner membrane,which is essential for the attachment of enzymes involved in the electron transport chain and $ATP$ synthesis.