Metabolic basis for living and Living State Questions in English

(A) For any spontaneous process occurring at constant temperature and pressure, the change in Gibbs free energy $(\Delta G)$ must be negative.
This means that the free energy of the system decreases as the process proceeds toward equilibrium.
Therefore, the correct option is $A$.

(A) spontaneous process is defined as a process that occurs without the need for continuous external energy input. According to the second law of thermodynamics,for any spontaneous process occurring at constant temperature and pressure,the Gibbs free energy $(G)$ of the system must decrease. Mathematically,this is expressed as $\Delta G < 0$. Therefore,the free energy of the system decreases during a spontaneous process.

(D) The living steady state is maintained by a self-regulatory mechanism known as $Homeostasis$.
$Homeostasis$ refers to the ability of an organism or cell to maintain internal equilibrium by adjusting its physiological processes.
This process involves various feedback mechanisms that detect changes in the internal environment and initiate responses to restore stability.
Therefore,$Homeostasis$ is the correct term for this self-regulatory state.

(A) The first law of thermodynamics,also known as the law of conservation of energy,states that energy can neither be created nor destroyed.
It can only be transformed from one form to another.
Therefore,the total energy of an isolated system,such as the universe,remains constant.

(D) Enzymes,vitamins,and hormones are essential biological molecules that act as regulators of metabolic processes.
Enzymes act as biological catalysts,vitamins often function as co-factors or precursors for co-enzymes,and hormones act as chemical messengers that regulate physiological activities.
Collectively,they are grouped together because they play a crucial role in controlling and regulating the various metabolic pathways within a living organism.

(C) Life is an emergent property of the interactions of molecules. This concept was proposed by $L. Pauling$ and $Zuckerkandl$ in the context of molecular evolution. They emphasized that biological properties arise from the complex organization and interaction of molecules within a cell,rather than being inherent to a single isolated molecule.

(B) Living systems are open systems that require a continuous input of energy to maintain their highly ordered state and to perform biological work.
According to the laws of thermodynamics,energy is lost as heat during metabolic processes (entropy increases).
To compensate for this loss and to maintain internal order,living organisms utilize $Gibbs$ free energy $(G)$.
Free energy is the portion of energy that is available to perform work at a constant temperature and pressure within a biological system.

(B) In biological systems,the efficiency of an organism is governed by thermodynamic principles.
According to the second law of thermodynamics,entropy $(S)$ represents the degree of disorder or randomness in a system.
An increase in entropy $(S)$ signifies a loss of energy quality and a move towards disorder,which reduces the efficiency of biological processes.
Conversely,free energy $(G)$ is the energy available to do useful work.
$A$ decrease in free energy $(G)$ limits the organism's ability to perform essential metabolic functions,thereby reducing its overall efficiency.
Therefore,the efficiency of a living organism decreases with an increase in entropy and a decrease in free energy.

(B) Living systems are open systems that maintain a state of low entropy (high order) by constantly exchanging energy and matter with their environment.
According to the second law of thermodynamics,entropy in an isolated system always increases.
To counteract this,living organisms consume free energy (usually derived from food) to perform metabolic work,which maintains their internal order and prevents the increase of entropy within the system.

(A) In thermodynamics,entropy is a measure of the disorder or randomness of a system. According to the second law of thermodynamics,for any spontaneous process,the total entropy of an isolated system always increases. $A$ state of maximum chemical instability represents a system far from equilibrium. As the system moves toward equilibrium to achieve stability,the entropy of the system increases until it reaches a maximum at equilibrium. Therefore,if the state of maximum chemical instability continues to transition toward equilibrium,the entropy increases.

(D) In thermodynamics and biological systems,$Entropy$ is defined as the measure of disorder or randomness within a system. Living organisms maintain a high degree of order by constantly consuming energy to counteract the natural tendency towards increased $Entropy$ (disorder) in the universe,as described by the second law of thermodynamics.

(C) Efficiency $(\eta)$ is defined as the ratio of useful work output to the total energy input. In thermodynamic systems, efficiency is related to the change in free energy $(\Delta G)$. When free energy increases (i.e., energy is consumed or stored in a non-spontaneous process), the net useful work output relative to the input energy decreases, leading to a reduction in overall efficiency. Therefore, efficiency decreases when free energy increases.

(A) The energy available to perform work in a biological system at constant temperature and pressure is called Gibbs free energy,commonly referred to as free energy. Living organisms utilize this energy to drive metabolic processes,maintain homeostasis,and perform cellular work.

(B) In thermodynamics and biological systems,$Entropy$ is defined as a measure of the degree of disorder or randomness within a system.
Living organisms maintain a state of low entropy (high order) by constantly consuming energy from their environment to counteract the natural tendency toward disorder.
Therefore,the measure of disorder in a system is referred to as $Entropy$.

(B) In thermodynamics and biological systems,entropy is defined as the measure of disorder or randomness within a system. Living organisms maintain a state of low entropy (high order) by constantly consuming energy from their environment to counteract the natural tendency toward increasing disorder.

(D) The living state is defined as a non-equilibrium steady state because living organisms must constantly perform work to maintain their structure and function.
If a system reaches equilibrium,it cannot perform any more work,which would lead to the death of the organism.
Metabolism is the sum total of all chemical reactions occurring in the body,and it is the process that maintains this non-equilibrium state.
Therefore,the living state and metabolism are essentially synonymous in the context of maintaining life.
Since all the given statements are scientifically accurate,the correct option is $D$.

(A) In a normal healthy individual,the concentration of glucose in the blood is maintained within a range of $4.2-6.1\ mmol/L$ (or approximately $4.5-5.0\ mM$).
In contrast,hormones are chemical messengers present in the blood in extremely low concentrations,typically measured in $\text{nanograms}/mL$ $(ng/mL)$.
Therefore,option $A$ correctly identifies the physiological ranges for both glucose and hormones as described in the $NCERT$ textbook regarding the 'Living State'.

(D) The correct answer is $D$.
$1$. Ribozymes are indeed $RNA$ molecules that possess catalytic activity,so option $A$ is correct.
$2$. Enzymes are proteins that fold into complex $3D$ structures,including tertiary and sometimes quaternary levels,so option $B$ is correct.
$3$. In an energy profile diagram,if the potential energy of the product $(P)$ is lower than the substrate $(S)$,energy is released,characterizing an exothermic reaction,so option $C$ is correct.
$4$. Metabolism is the sum total of all chemical reactions occurring in a living organism. The living state is defined by a constant turnover of biomolecules through metabolic pathways; therefore,the living state is impossible without metabolism. Thus,option $D$ is incorrect.

(N/A) Living organisms are open systems that maintain a state of low entropy (high order) by constantly exchanging energy and matter with their environment.
According to the $2^{nd}$ law of thermodynamics,the entropy of an isolated system always increases over time.
In living organisms,metabolic processes require energy to maintain cellular structure and repair damage.
As an organism ages,its ability to efficiently utilize energy to counteract the natural increase in entropy declines.
Eventually,the accumulation of disorder (entropy) within the biological system exceeds the organism's capacity to maintain homeostasis,leading to the breakdown of vital functions and ultimately death.

(N/A) $\rightarrow$ Metabolic pathways lead to a more complex structure from a simpler structure (e.g.,acetic acid is converted into cholesterol) or simpler substances from a complex structure (e.g.,glucose is converted into lactic acid in our skeletal muscle).
$\rightarrow$ The first type of reactions are called anabolic pathways. The latter constitute catabolic pathways.
$\rightarrow$ Anabolic pathways consume energy; for example,the formation of protein from amino acids requires energy input. Catabolic pathways lead to the release of energy; for example,when glucose is converted to lactic acid in our skeletal muscle,energy is liberated.
$\rightarrow$ The metabolic pathway from glucose to lactic acid occurs in $10$ metabolic steps and is called glycolysis.
$\rightarrow$ Living organisms trap this energy liberated during degradation and store it in the form of chemical bonds.
$\rightarrow$ As and when required,this bond energy is utilized for biosynthetic,osmotic,and mechanical work performed by organisms.
$\rightarrow$ The most important form of energy currency in living systems is the bond energy in the form of $ATP$ (Adenosine Triphosphate).

(N/A) $\rightarrow$ Thousands of chemical compounds, known as metabolites, are present in living organisms at characteristic concentrations.
$\rightarrow$ For example, the blood concentration of glucose in a normal healthy individual is $4.5-5.0 \; mM$, while hormones are present in nanogram concentrations.
$\rightarrow$ Biological systems exist in a steady state characterized by the constant concentration of these biomolecules, which are maintained through metabolic flux.
$\rightarrow$ Any chemical or physical process moves spontaneously toward equilibrium. However, the steady state of a living organism is a non-equilibrium state.
$\rightarrow$ From physics, it is known that systems at equilibrium cannot perform work.
$\rightarrow$ Since living organisms must perform work continuously to survive, they cannot afford to reach equilibrium. Therefore, the living state is a non-equilibrium steady state to enable the performance of work.
$\rightarrow$ The living process is a constant effort to prevent falling into equilibrium, which is achieved through energy input. Metabolism provides the mechanism for this energy production.
$\rightarrow$ Consequently, the living state cannot exist without metabolism.

(B) No,biomolecules like $DNA$ and protein cannot exhibit biological activity in anhydrous conditions.
Water acts as a solvent and provides the necessary medium for biochemical reactions to occur.
In the absence of water (anhydrous conditions),the structural conformation of these molecules is often lost or stabilized in an inactive state.
Therefore,water is essential for maintaining the biological activity of these molecules and is inevitable for life.

(N/A) Living organisms do not exist in equilibrium because a system at equilibrium cannot perform work.
Living organisms exist in a steady state characterized by the constant concentrations of various biomolecules.
These biomolecules are constantly undergoing metabolic flux,meaning they are being synthesized and broken down continuously.
Any chemical or physical process moves spontaneously toward equilibrium.
Since living organisms must perform work continuously to survive,they cannot afford to reach equilibrium.
Therefore,the living state is defined as a non-equilibrium steady state to ensure the ability to perform work.

(D) The living steady state refers to the maintenance of a constant internal environment within an organism. This self-regulatory mechanism that allows living organisms to maintain a stable internal environment despite changes in external conditions is known as homeostasis.

(A) Metabolic processes are highly regulated chemical reactions that occur within living organisms.
$1$. All metabolic reactions are catalyzed by enzymes.
$2$. Enzymes are proteins (with rare exceptions like ribozymes) that speed up these reactions.
$3$. Without these catalysts,metabolic reactions would be extremely slow and insufficient to sustain life.
$4$. Therefore,the statement that metabolic processes can occur without catalysts is incorrect.
$5$. Metabolic reactions can indeed occur in cell-free systems (in vitro) and involve the transformation of biomolecules.

(A) The living state is defined as a non-equilibrium steady state.
Living organisms exist in a steady state because they are constantly receiving energy from their environment to perform work and maintain their structure.
If a system reaches equilibrium,it means the system has stopped performing work and is essentially dead.
Therefore,to remain alive,organisms must constantly prevent reaching equilibrium,which is achieved through continuous metabolic processes.