Origin of Life Questions in English

(C) The correct answer is the origin of the $Universe$.
There are several theories regarding the origin of the $Universe$, but the most widely accepted one is the $Big-Bang$ theory.
$Big-Bang$ Theory: This theory was proposed by $Abbe$ $Lemaitre$ in $1931$. According to the $Big-Bang$ theory, about $15$ billion years ago, all cosmic matter was in a highly condensed form. $A$ massive explosion occurred, which broke the condensed matter and scattered its fragments into space at an enormous velocity. This event produced a $Big-Bang$ sound, and thus the theory came to be known as the $Big-Bang$ theory.

(D) The theory of panspermia,also known as the cosmozoic theory,was proposed by Richter $(1865)$.
According to this theory,life reached Earth in the form of spores,germs,or other simple particles from unknown parts of the universe along with cosmic dust.
These particles subsequently evolved into various forms of life on Earth.
Since panspermia,cosmozoic theory,and spore theory all refer to the same concept of extraterrestrial origin of life,the correct answer is 'All of these'.

(A) Louis Pasteur performed the swan-necked flask experiment to demonstrate the theory of biogenesis.
This experiment proved that all living organisms originate from pre-existing living organisms (germs/spores).
By showing that no life appeared in the sterilized broth unless exposed to air containing microorganisms,he completely disproved the concept of spontaneous generation (abiogenesis).

(B) In $1953$,Stanley Miller and Harold Urey conducted an experiment to test the Oparin-Haldane hypothesis regarding the origin of life.
They created a closed system simulating the conditions of the primitive Earth.
The mixture of gases used in the spark-discharge apparatus consisted of methane $(CH_{4})$,ammonia $(NH_{3})$,hydrogen $(H_{2})$,and water vapor $(H_{2}O)$.
Therefore,along with $NH_{3}$ and $H_{2}$,they used $CH_{4}$ and $H_{2}O$.

(B) In $1953$,Stanley Miller and Harold Urey synthesized amino acids by passing an electric discharge through a mixture of methane $(CH_{4})$,ammonia $(NH_{3})$,hydrogen $(H_{2})$,and water vapour $(H_{2}O)$.
Carbon dioxide $(CO_{2})$ was not present in the Urey-Miller experiment mixture.

(D) The chemical theory of the origin of life is the most widely accepted theory.
In $1953$,Stanley Miller,who was then a graduate student of Harold Urey $(1893-1981)$ at the University of Chicago,clearly demonstrated that ultraviolet radiation or electric discharges can produce complex organic compounds from a mixture of $CH_{4}$,$NH_{3}$,$H_{2}O$,and $H_{2}$. The ratio of methane,ammonia,and hydrogen in Miller's experiment was $2:1:2$.
Experimental Evidences of Chemical Evolution:
Stanley Miller and Harold Urey performed an experiment in $1953$ to test the chemical theory of evolution.
They created an electric discharge in a closed flask containing $CH_{4}$,$H_{2}$,$NH_{3}$,and water vapor at $800^{\circ}C$. They observed the formation of amino acids. In similar experiments,others observed the formation of sugars,nitrogen bases,pigments,and fats.
The first non-cellular forms of life could have originated $3$ billion years ago. The first cellular form of life possibly did not originate until about $2$ billion years ago because the conditions were non-biogenic at that time. This version of abiogenesis,i.e.,the first form of life arose slowly through evolutionary forces from non-living molecules,was accepted by the majority.

(A) In $1953$,$Stanley \ Miller$ synthesized organic compounds under conditions resembling the primitive atmosphere of the earth. $A$ mixture of water vapour,methane,hydrogen,and ammonia was circulated through a closed apparatus by steam from boiling water and subjected to an electric spark discharge $(7000 \ V)$ between tungsten electrodes. This apparatus was permitted to run for a week. The result was the formation of several amino acids.

(A) Plants were the first organisms to invade land. They were present on land long before animals arrived,providing the necessary oxygen and food sources for subsequent life forms.

(D) The correct answer is $D$. All of the above.
Oparin and Haldane's theory,which explains the origin of life on Earth,is known by several names:
$1$. $\text{Chemical theory of origin of life}$: It suggests that life originated from non-living organic molecules through a series of chemical reactions.
$2$. $\text{Modern theory of origin of life}$: It is considered the most widely accepted modern scientific explanation for the origin of life.
$3$. $\text{Naturalistic theory}$: It explains the origin of life through natural processes rather than supernatural intervention.
Therefore,all the given options are correct.

(C) The $Proterozoic$ era is characterized by the appearance of the first eukaryotic organisms.
During this era,simple multicellular life forms such as $Protozoa$,sponges,and various forms of algae began to evolve and diversify in the oceans.
This era followed the $Archean$ eon and preceded the $Phanerozoic$ eon,marking a significant step in the history of life on Earth.

(B) $Spallanzani$ disapproved the theory of abiogenesis (spontaneous generation).
$Spallanzani$'s Experiment: He experimented that animal and vegetable broths boiled for several hours and soon after sealed, were never infested with microorganisms.
From this experiment, he concluded that high temperature had killed all living organisms in the broths and without them, life did not appear.
When the broths were left exposed to air, they were soon invaded by microorganisms.
Therefore, the pair $Spallanzani - \text{Approve abiogenesis}$ is incorrect.

(B) Stanley Miller and Harold Urey synthesized amino acids by passing an electric discharge through a mixture of ammonia $(NH_3)$,hydrogen $(H_2)$,water vapor $(H_2O)$,and methane $(CH_4)$.
The ratio of methane $(CH_4)$,ammonia $(NH_3)$,and hydrogen $(H_2)$ used in the large flask was $2: 1: 2$.

(C) Life cannot originate from inorganic materials now because of high atmospheric oxygen. Oxygen is potentially very dangerous to living things,because it reacts with organic molecules,destroying these molecules and releasing their stored energy.

(D) The experiment where meat was not spoiled when heated and kept sealed in a vessel suggested that the simplest living organisms could not have originated spontaneously from non-living matter.
This experiment,often associated with the work of $Lazzaro$ $Spallanzani$,demonstrated that microorganisms are present in the air and that they are the source of contamination in organic matter.
By boiling the broth or meat and sealing the container,the entry of microbes from the air was prevented,thus proving that life does not arise spontaneously from non-living matter (abiogenesis).

(D) Abiogenesis refers to the natural process by which life has arisen from non-living matter,such as simple organic compounds.
$I.$ Spontaneous generation is the hypothetical process by which living organisms develop from non-living matter.
$IV.$ Origin of life from non-living organism is the fundamental definition of abiogenesis.
Therefore,statements $I$ and $IV$ support the concept of abiogenesis.

(D) Let us analyze the given statements:
$I.$ The swan-neck flask experiment was indeed performed by Louis Pasteur to disprove spontaneous generation. This statement is correct.
$II.$ Louis Pasteur is widely recognized for his contributions to the germ theory of disease. This statement is correct.
$III.$ Louis Pasteur successfully demonstrated that life comes from pre-existing life,thereby permanently disproving the theory of spontaneous generation. This statement is correct.
$IV.$ The Cosmozoic theory (or Panspermia theory) suggests that life reached Earth from other planets in the form of spores or germs. This theory was proposed by Richter in $1865$. This statement is correct.
$V.$ The theory of catastrophism,which suggests that Earth's geological features were formed by sudden,short-lived,violent events,was proposed by Georges Cuvier. This statement is correct.
Since all the statements provided ($I, II, III, IV,$ and $V$) are scientifically accurate,there are no wrong statements among them.

(B) The evolutionary sequence of life on Earth is as follows:
$1$. First heterotrophic prokaryotes $(I)$: These were the earliest life forms that utilized existing organic molecules for energy.
$2$. First autotrophic prokaryotes $(III)$: As organic resources became scarce,organisms evolved the ability to synthesize their own food (e.g.,chemosynthesis and later photosynthesis).
$3$. First eukaryotes $(II)$: These evolved from prokaryotes through endosymbiosis,characterized by a membrane-bound nucleus and organelles.
$4$. First animals $(IV)$: Multicellular eukaryotic organisms appeared much later in the evolutionary timeline.
Therefore,the correct chronological order is $I, III, II, IV$.

(B) The origin of the universe occurred approximately $20$ billion years ago.
The origin of the Earth is estimated to have occurred approximately $4.5$ billion years ago,which is equivalent to $4500$ million years.
Therefore,the range $4000-4600$ million years ago is the correct scientific estimate.

(C) Louis Pasteur finally refuted the theory of spontaneous generation. He performed the famous 'Swan-neck flask experiment'. In this experiment,he showed that in pre-sterilized flasks,life did not come from killed yeast,while in another flask open to air,new living organisms arose from 'life' existing in the air. This experiment conclusively disproved the concept of spontaneous generation.

(C) Based on the hypothesis proposed by Oparin and Haldane,Stanley Miller provided experimental evidence for chemical evolution.
In $1953$,he created a laboratory setup simulating the conditions of the primitive atmosphere,such as high temperature,volcanic storms,and a reducing atmosphere consisting of $CH_4$,$NH_3$,$H_2$,and water vapor.
He observed the formation of amino acids,which are the building blocks of organic compounds,thereby supporting the theory of chemical evolution.

(D) The $Cosmozoic$ $theory$,also known as the $Panspermia$ $theory$,suggests that life did not originate on Earth but was brought here from other parts of the universe.
According to this theory,life exists throughout the universe and is transferred from one planet to another in the form of resistant seeds,spores,or other biological units.

(C) Stanley Miller conducted a famous experiment in $1953$ to test the Oparin-Haldane hypothesis regarding the origin of life.
He created a closed system in the laboratory that simulated the conditions of the primitive Earth.
He used a mixture of gases consisting of $CH_{4}$ (methane),$NH_{3}$ (ammonia),$H_{2}$ (hydrogen),and water vapour $(H_{2}O)$ in a ratio of $2:1:2$.
These gases were subjected to electric discharges using electrodes to simulate lightning.
After $18$ days,he observed the formation of simple amino acids like glycine,alanine,and aspartic acid,which provided experimental evidence for the chemical evolution of life.

(B) The theory of spontaneous generation,also known as abiogenesis,suggested that living organisms could arise from non-living matter.
$Van \ Helmont$ was a notable proponent of this theory,famously suggesting that mice could arise from wheat and a dirty shirt.
In contrast,$Louis \ Pasteur$,$Spallanzani$,and $Francisco \ Redi$ conducted experiments that ultimately disproved the theory of spontaneous generation,demonstrating that life arises only from pre-existing life.

(B) $J. B. S. Haldane$ was a British-born scientist who made significant contributions to the study of the origin of life.
He proposed the chemical evolution theory,suggesting that life originated from non-living organic molecules.
He moved to India in $1957$,became an Indian citizen,and spent the later part of his life working at the Indian Statistical Institute in Kolkata.

(D) The cosmozoic theory,also known as the theory of 'Panspermia',suggests that life did not originate on Earth but was brought here from outer space. According to this theory,life existed in the form of resistant units such as spores,seeds,or other simple reproductive structures that could survive the harsh conditions of space travel. Therefore,all of the listed options are considered potential vehicles for the transfer of life according to this theory.

(C) The theory of Panspermia suggests that life exists throughout the Universe and is distributed by space dust,meteoroids,asteroids,comets,or planetoids.
This theory is supported by the study of meteorites,which are fragments of rock or metal from outer space that fall to the Earth's surface.
Scientists have analyzed the chemical composition of meteorites and found organic compounds,which provides evidence for the possibility of extraterrestrial life origins.

(A) Alexander Oparin was a Russian biochemist who proposed the theory of the chemical origin of life in $1924$.
$J$.$B$.$S$. Haldane was a British scientist who independently proposed a similar theory.
Therefore,Oparin is the correct answer as he was the Russian scientist.

(B) $A.I.$ Oparin is a famous scientist known for his theory on the chemical evolution of life. He authored the book titled "The Origin of Life" in $1924$.
Matching the other options:
$1$. "Origin of Species" was written by Charles Darwin.
$2$. "Philosophie Zoologique" was written by Jean-Baptiste Lamarck.
$3$. "The Planets" (or related works on planetary science) is often associated with $H.C.$ Urey.

(A) The book titled "The Planets" was written by $H.C. Urey$.
"Origin of Species" was written by $Charles \, Darwin$.
"The Origin of Life" was written by $A.I. Oparin$.
Therefore, the correct option is $A$.

(B) $S.L.$ Miller conducted an experiment in $1953$ to test the Oparin-Haldane hypothesis. He created a closed system with a mixture of $CH_4$,$NH_3$,$H_2$,and water vapor at $800^{\circ}C$ using electric discharges. After a week,he observed the formation of simple organic compounds,specifically amino acids such as alanine,glycine,and aspartic acid.

(C) The chemical evolution theory,proposed by Oparin and Haldane,suggests that the first forms of life originated from pre-existing non-living organic molecules.
In $1953$,$S.L.$ Miller conducted an experiment to test this hypothesis by creating a laboratory environment that simulated the conditions of the primitive Earth (high temperature,volcanic storms,and a reducing atmosphere containing $CH_4$,$NH_3$,$H_2$,and $H_2O$).
He observed the synthesis of amino acids in his apparatus,which provided experimental evidence for the chemical evolution of life.

(B) Louis Pasteur is the scientist who performed the famous swan-necked flask experiment.
This experiment provided conclusive evidence to disprove the theory of spontaneous generation (abiogenesis).
He demonstrated that life arises only from pre-existing life (biogenesis),as microorganisms could not grow in the sterile broth of the swan-necked flask because they were trapped in the neck.

(C) The early atmosphere of the Earth was a reducing atmosphere,characterized by the presence of hydrogen,methane,ammonia,and water vapor,but lacking free oxygen. Therefore,an oxidising atmosphere was not present on early Earth.

(D) On the early Earth,high-energy $UV$ radiations from the sun caused the photolysis of water vapor $(2H_{2}O \xrightarrow{UV} 2H_{2} + O_{2})$.
Since hydrogen is a light gas,it escaped into space.
The released oxygen combined with ammonia $(NH_{3})$ and methane $(CH_{4})$ to form water $(H_{2}O)$,carbon dioxide $(CO_{2})$,and other compounds.

(D) The early atmosphere of the Earth was reducing in nature,meaning it lacked free oxygen. Oxygen was released into the atmosphere as a byproduct of photosynthesis by early photosynthetic organisms like cyanobacteria and later by plants. Therefore,free oxygen appeared on Earth only after the evolution of photosynthetic life forms.

(A) The theory of abiogenesis,which suggested that life could originate from non-living matter spontaneously,was finally disproved by Louis Pasteur.
He conducted the famous 'Swan-Neck Flask' experiment,which demonstrated that microorganisms only arise from pre-existing microorganisms in the air,thereby supporting the theory of biogenesis.

(D) The origin of the Earth occurred approximately $4.5 \text{ billion}$ years ago.
Cyanobacteria-like organisms are considered to be among the earliest forms of life,appearing on Earth about $3.3 \text{ to } 3.5 \text{ billion}$ years ago.

(A) Eukaryotes are complex cells that evolved from prokaryotic ancestors through the process of endosymbiosis.
According to evolutionary biology and the fossil record, the first free-living eukaryotic organisms originated in the oceans approximately $1.5 \; \text{billion}$ years ago, which is equivalent to $1,500 \; \text{million}$ years ago.
Among the given options, $1,600 \; \text{million}$ years ago is the closest approximation to this timeline.

(B) Autotrophic cyanobacteria were the first organisms to perform oxygenic photosynthesis.
They used $H_{2}O$ as a hydrogen donor to obtain hydrogen for carbon fixation,which resulted in the release of oxygen as a byproduct.
This process led to the accumulation of free oxygen in the atmosphere,causing it to become oxidising.

(B) The atmosphere of primitive Earth was a reducing environment. It contained gases like $CH_4$,$NH_3$,$H_2$,and water vapor,but it lacked free molecular oxygen $(O_2)$. Oxygen was released later into the atmosphere through the process of photosynthesis by cyanobacteria.

(A) The theory of spontaneous generation,also known as abiogenesis,proposed that life could arise spontaneously from non-living,decaying,and rotting matter such as straw,mud,or sweat. This theory was later disproven by experiments conducted by scientists like Francesco Redi,Lazzaro Spallanzani,and finally Louis Pasteur,who demonstrated that life comes only from pre-existing life (biogenesis).

(C) Louis Pasteur performed the famous $Swan-Neck$ flask experiment.
In this experiment,he showed that in pre-sterilized flasks,life did not come from killed yeast if the flask was sealed,but when exposed to air,new living organisms arose from pre-existing life forms present in the air.
This experiment effectively disproved the theory of spontaneous generation and provided evidence for $BIOGENESIS$,which states that life comes from pre-existing life.

(C) According to the theory of chemical evolution, the first non-cellular forms of life originated approximately $3 \; \text{billion}$ years ago.
These were likely giant molecules such as $RNA$, $DNA$, and polysaccharides that were capable of self-replication or complex chemical interactions.

(D) Nucleic acids are considered the most essential for the origin of life because they serve as the genetic material (the blueprint of an organism's genetic make-up). They possess the unique ability to store,replicate,and transmit genetic information,which is fundamental for self-replication and evolution.

(A) The presence of $NaCl$ (sodium chloride) in the body fluids of organisms is considered evidence that life originated in the primitive ocean. The concentration of salts in our internal body fluids is similar to the salinity of the ancient oceans where the first life forms evolved.

(B) The theory of spontaneous generation,also known as $Abiogenesis$,proposes that living organisms can originate from non-living matter.
This concept suggests that life arises naturally from inanimate substances under certain conditions.

(C) According to the Oparin-Haldane hypothesis,the early atmosphere was reducing and contained simple molecules like $CH_{4}$,$NH_{3}$,$H_{2}O$,and $H_{2}$.
Energy sources such as lightning and ultraviolet $(UV)$ radiation provided the necessary activation energy for these simple molecules to react and form complex organic compounds like amino acids and nucleotides in the primitive ocean.
$UV$ rays also played a role in the photolysis of water,breaking $H_{2}O$ into $H_{2}$ and $O_{2}$.

(B) The theory of panspermia,also known as the theory of cosmic origin,suggests that life did not originate on Earth but was brought to Earth from outer space in the form of resistant spores,seeds,or microorganisms.
It proposes that life exists throughout the Universe and is distributed by meteoroids,asteroids,comets,or planetoids.
Therefore,it is a hypothesis proposed to explain the origin of life on Earth.

(A) The first organisms on Earth are believed to have been chemoheterotrophs.
These primitive life forms obtained their energy and carbon from the organic molecules present in the 'primordial soup' of the early oceans.
They did not possess the machinery for photosynthesis or chemosynthesis,making them dependent on pre-existing organic compounds.

(A) Life originated in the primitive oceans,which provided the necessary aqueous environment for the synthesis of complex organic molecules. Water acts as a universal solvent and is essential for all biochemical reactions,making it the most critical condition for the origin of life.