Biological Evolution Questions in English

(A) Two or more species that inhabit the same geographical area and are reproductively isolated from each other are known as $Sympatric$ species.
These species occupy the same or overlapping ranges but do not interbreed due to various ecological,behavioral,or genetic barriers.
In contrast,$Allopatric$ species are those that inhabit different geographical areas.
Therefore,the correct option is $A$.

(D) The correct answer is $D$.
Species that inhabit different geographical areas and are separated by physical barriers are known as allopatric species.
These species evolve independently due to geographical isolation,which prevents gene flow between populations.

(B) The process of formation of new species from existing ones is known as $Speciation$.
$Speciation$ involves the multiplication of species through evolutionary mechanisms such as reproductive isolation and genetic divergence.
Therefore,the multiplication of species is synonymous with $Speciation$.

(B) The evolution of higher taxonomic categories such as new orders,classes,phyla,etc.,is referred to as macroevolution.
Microevolution refers to changes in gene frequency within a population over a short period.
Therefore,the correct answer is $B$.

(C) In biology,the term 'evolution' refers to the process of gradual change in the inherited characteristics of biological populations over successive generations.
This process involves the descent with modification,where living organisms undergo changes over time,leading to the diversity of life observed today.
Therefore,the most accurate description among the given options is that living things constantly change over long periods.

(D) Convergent evolution is the process whereby organisms not closely related (not monophyletic) independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
When animals from two different lineages exhibit significant morphological or physiological similarities due to similar selective pressures,it is termed convergent evolution.
Examples include the wings of insects,birds,and bats,or the streamlined bodies of sharks and dolphins.

(A) Speciation is the evolutionary process by which populations evolve to become distinct species.
Geographic isolation prevents gene flow between populations due to physical barriers,leading to genetic divergence.
Reproductive isolation ensures that individuals of different populations cannot interbreed,which is a fundamental requirement for the formation of new species.
Therefore,both geographic and reproductive isolation are key mechanisms driving the process of speciation.

(C) Organic evolution is the process of gradual change in the inherited characteristics of biological populations over successive generations.
One of the fundamental observations of evolution is the trend towards increasing complexity in organisms over geological time,as simpler life forms evolved into more complex and specialized structures.

(B) is the correct answer. Micro-evolution refers to the small-scale changes in allele frequencies within a population over a few generations. These changes occur at the sub-species level due to gene mutations,natural selection,and genetic drift,which do not lead to the formation of new species.

(B) Speciation is the evolutionary process by which populations evolve to become distinct species.
It involves the formation of new and distinct species in the course of evolution from pre-existing species.
Isolation,polyploidy,and biogeography are factors or mechanisms that can contribute to speciation,but they are not the term for the origin of species itself.

(C) Parallel evolution occurs when closely related species evolve similar traits independently while adapting to similar environmental pressures.
Unlike convergent evolution,which involves unrelated species,parallel evolution involves species that share a common ancestor and maintain a similar level of genetic similarity while developing analogous adaptations.

(D) Industrial melanism is a classic example of natural selection. In industrial areas,the soot from factories darkened the tree trunks. Moths with darker pigmentation (melanic forms) were better camouflaged against these soot-covered trees,protecting them from predators. This is an example of protective resemblance with the surrounding environment,which allowed the dark-colored moths to survive and reproduce more successfully than the light-colored ones.

(C) The correct answer is $C$. Neo-Darwinism emerged as the 'Modern Synthetic Theory' of evolution.
It was designated by Huxley in $1942$.
Dobzhansky's $1937$ book, "Genetics and the Origin of Species," provided the initial basis for this theory.
Scientists such as Muller $(1949)$, Fisher $(1958)$, Wright $(1968)$, Mayr $(1963, 1970)$, and Stebbins $(1966-1976)$ contributed significantly to its formulation.

(B) Evolution is defined as the process of gradual change in the inherited characteristics of biological populations over successive generations. Charles Darwin famously described this process as 'descent with modification',which implies that all organisms are related through common ancestry and have changed over time due to natural selection and other evolutionary mechanisms.

(A) Evolution is a gradual and ongoing biological process. It involves the change in the heritable characteristics of biological populations over successive generations. Since life began on Earth,the process of evolution has been occurring continuously and continues to occur today,leading to the diversification of species.

(B) The book "Genetics and the Origin of Species" was written by Theodosius Dobzhansky in $1937$.
This landmark work played a crucial role in the development of the Modern Synthetic Theory of evolution by integrating Mendelian genetics with Darwinian natural selection.

(A) Evolution is the process of gradual change in the inherited characteristics of a population over successive generations.
For an adaptation to contribute to evolution,it must be heritable,meaning it can be passed from parents to offspring through genetic material.
Furthermore,evolutionary changes typically occur over a long period,involving the accumulation of these heritable traits within a population.
Therefore,adaptations that are long-term and heritable are the primary drivers of evolutionary change.

(B) The diversity observed in living organisms is primarily the result of long-term evolutionary changes. Over millions of years,natural selection,genetic drift,and mutations accumulate in populations,leading to speciation and the vast biological diversity we see today. While mutations are the source of new genetic variation,the overall diversity of life is a consequence of the cumulative effect of evolutionary processes over geological time.

(B) The diversity observed in plant life is primarily the result of $evolutionary$ processes that have occurred over millions of years. Through the mechanism of natural selection and adaptation to changing environmental conditions,plants have diversified into various forms,ranging from simple algae to complex angiosperms. This long-term $evolutionary$ change has allowed plants to colonize diverse habitats across the globe.

(A) Industrial melanism is a classic example of natural selection.
Before industrialization in England, the white-winged moths were more abundant on tree trunks covered with lichens, which provided camouflage against predators.
With industrialization, soot and smoke killed the lichens and darkened the tree trunks.
In this new environment, the dark-winged (melanic) moths were better camouflaged and thus had a survival advantage over the white-winged moths.
Therefore, the dark form was naturally selected in polluted industrial areas.

(A) Industrial melanism is a classic example of natural selection. During the industrial revolution in England,the soot from factories darkened the tree trunks. The light-colored moths,which were previously camouflaged,became easily visible to predators,while the dark-colored (melanic) moths gained a survival advantage. This change in the environment led to the selection of the dark-colored variant,demonstrating how natural selection acts on existing variations in a population.

(B) Evolution is a stochastic process based on chance events in nature and chance mutation in the organisms. It is not a directed process with a predetermined goal,meaning it is not deterministic. Therefore,it is considered a stochastic process.

(A) The book 'Genetics and the Origin of Species' was written by Theodosius Dobzhansky in $1937$. This work played a crucial role in the development of the Modern Synthetic Theory of Evolution by bridging the gap between Mendelian genetics and Darwinian natural selection.

(B) The loss of limbs in snakes is a classic example of evolutionary adaptation. Snakes evolved from limbed ancestors (lizard-like reptiles). During the course of evolution,as they adapted to a burrowing or slithering lifestyle,the selective pressure led to the reduction and eventual loss of limbs. This is a result of natural selection and genetic changes over millions of years,not a result of individual effort or disuse during a single lifetime.

(C) The theory of evolution,as proposed by Charles Darwin and modern synthesis,describes the process of biological change over time.
It is fundamentally based on the concept of gradual change in the inherited characteristics of biological populations over successive generations.
Therefore,evolution is synonymous with the process of gradual change in living organisms.

(B) When different groups of organisms evolve to possess similar structures or traits due to adaptation to similar environmental conditions or needs,this process is known as $Convergent \ evolution$.
This leads to the development of analogous organs,which perform similar functions but have different evolutionary origins.
For example,the wings of butterflies and birds are analogous structures that evolved independently to serve the function of flight.

(B) According to the theory of natural selection,fitness is the end result of the ability to adapt and get selected by nature.
Darwinian variations are small and directional,not directionless.
All mammals,including whales and camels,have seven cervical vertebrae.
Mutations are random and directionless,not directional.

(C) The phenomenon described is $Divergent$ $evolution$.
$Divergent$ $evolution$ occurs when organisms with a common ancestor evolve different traits or adaptations to survive in different environments.
Since whales, dolphins, bats, monkeys, and horses all share a common mammalian ancestor but have adapted to diverse habitats (aquatic, aerial, terrestrial), they exhibit homologous structures that have diverged over time due to different selective pressures.

(C) The theory of organic evolution,specifically the concept of descent with modification,was proposed by Charles Darwin. It suggests that species change over time,give rise to new species,and share a common ancestor. This process is driven by natural selection,where traits that enhance survival and reproduction are passed on to subsequent generations,leading to gradual changes in populations over time.

(C) Industrial melanism is a classic example of natural selection. During the industrial revolution in England,the tree trunks became covered with soot from industrial smoke,turning them dark. The light-colored moths,which were previously camouflaged against lichen-covered light tree trunks,became easily visible to predators. Conversely,the dark-colored moths (melanic forms) gained a survival advantage due to their protective resemblance with the soot-covered dark tree trunks. This phenomenon demonstrates how environmental changes lead to the selection of traits that provide better camouflage or protective resemblance.

(A) When a population is split into two or more groups by a physical or geographical barrier (such as a mountain range,river,or ocean),it prevents gene flow between them. Over time,these isolated populations evolve independently due to different selective pressures and genetic drift,leading to speciation. Such species that evolve in different geographical areas are known as $Allopatric$ species.

(D) Long-term adaptation refers to the process by which a population becomes better suited to its environment over many generations.
$1$. It is $Heritable$ because these traits are passed from parents to offspring through genetic material.
$2$. It is a $Result of evolution$ as it occurs through the mechanism of natural selection acting on genetic variations over time.
$3$. It is considered $Permanent$ in the context of the population's lineage as long as the selective pressure persists.
Therefore, all the given statements are correct.

(A) Species that evolve in different geographical areas and are separated by physical or geographical barriers are known as $Allopatric$ species. This process of speciation is called $Allopatric$ speciation. In contrast,$Sympatric$ species evolve within the same geographical area. Therefore,the correct option is $A$.

(D) Evolution is the process by which living organisms have developed and diversified from earlier forms during the history of the earth.
It explains how simple,primitive life forms gradually changed over millions of years to give rise to more complex and higher organisms.
Adaptation,variation,and migration are mechanisms or factors that contribute to the process of evolution,but the overall phenomenon of change from simple to complex forms is defined as evolution.

(C) Evolution is the process of gradual change in the inherited characteristics of biological populations over successive generations. It explains how simple,primitive organisms have diversified and transformed into complex,higher forms of life over millions of years through mechanisms like natural selection and genetic variation. Therefore,evolution is the fundamental process responsible for the increasing complexity in plant forms.

(C) When plant species migrated from water to land, they underwent a process of $Adaptation$.
Adaptation refers to the evolutionary process whereby an organism becomes better suited to live in its habitat or habitats.
As plants moved from an aquatic environment to a terrestrial one, they had to develop specific structures such as a waxy cuticle, stomata for gas exchange, and vascular tissues to survive and thrive on land.

(B) The formation of a new species,known as speciation,is primarily driven by the accumulation of genetic variations over generations.
Genetic variation provides the raw material for natural selection to act upon.
When populations of a species become geographically or reproductively isolated,these accumulated variations lead to divergence,eventually resulting in the formation of a new,distinct species.

(C) The correct answer is $C$.
Convergent evolution is the development of superficially similar structures in unrelated organisms,usually because the organisms live in the same kind of environment.
This phenomenon occurs when different groups of organisms evolve similar adaptive features to perform the same function due to similar environmental pressures.
Examples include the wings of insects,birds,and bats,which serve the same function of flight but evolved independently.
Another example is the streamlined body shape of whales (mammals) and fish,which evolved independently to facilitate movement in an aquatic environment.

(B) The phenomenon of industrial melanism is a classic example of natural selection.
Before industrialization in England,white-winged moths were more abundant because they could camouflage against the light-colored lichens on tree trunks.
After industrialization,the tree trunks became dark due to soot and smoke,which killed the lichens.
This environment favored the dark-winged (melanised) moths,as they were better camouflaged against predators,while the white-winged moths were easily spotted and eaten.
Therefore,melanised moths were dark-winged.

(C) The diversity observed in living organisms is primarily the result of long-term evolutionary changes. Over millions of years,processes such as natural selection,genetic drift,and mutation lead to the accumulation of variations,resulting in the vast biodiversity we see today.

(C) Diversity among living organisms is primarily the result of long-term evolutionary changes.
Evolution is a process that occurs over millions of years,leading to the accumulation of genetic variations through mechanisms like mutation,natural selection,and genetic drift.
These accumulated changes over vast geological time scales result in the speciation and the immense biological diversity observed today.

(C) Convergent evolution occurs when organisms that are not closely related independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
Even if the genotypes are different,the phenotypic similarity arises due to similar selective pressures in the environment.
This process leads to the development of analogous structures.

(B) Industrial melanism is a classic example of natural selection. Before industrialization in England, the light-colored form of the peppered moth was more abundant as it could camouflage against lichen-covered tree trunks. With the onset of industrialization, soot covered the trees, making the dark-colored (melanic) form better camouflaged against predators. This provided the dark-colored moths with a selective advantage in polluted industrial areas, leading to an increase in their population frequency. Thus, it demonstrates that natural selection favors traits that provide a survival advantage in a changing environment.

(D) When two or more unrelated or distantly related species evolve similar traits as a result of having to adapt to similar environments or ecological niches,this process is known as $Convergent \ evolution$.
This leads to the development of analogous organs,which perform similar functions but have different evolutionary origins.
For example,the wings of butterflies and birds,or the flippers of dolphins and penguins,show convergent evolution.

(A) In the true sense,natural selection for evolution on Earth began when cellular forms of life with different metabolic capabilities originated.
The core essence of Darwinian evolution is natural selection. The rate of appearance of new forms is linked to the life cycle or life span. Microbes that divide rapidly have high multiplication ability and reach millions in numbers within hours.
$A$ colony of bacteria (say $A$) growing in a given medium has variations in terms of their ability to utilize feed components. If the composition of the medium is changed,only that part of the population (say $B$) will survive that can withstand the new changed conditions. Over a period of time,this variant population will outgrow the others and appear as a new species.
This happens within a few days. However,when the same is applied to fish or fowl,it takes millions of years because their life span is in years. Here,we can say that the fitness of $B$ is better than $A$ under the new conditions. Nature selects for fitness. It is important to remember that the so-called fitness is based on characteristics which are heritable.
Therefore,there must be a genetic basis for selection and evolution. In other words,some organisms are better adapted to survive in an otherwise changing environment. Adaptability is inherited. It has a genetic basis. Fitness is the end result of the ability to adapt and get selected by nature.
Branching descent and natural selection are the two key concepts of Darwinian theory of evolution.

(A) In $1850s$,i.e.,before industrialisation,it was observed that there were more white-winged peppered moths $(Biston \ betularia)$ on trees than dark-winged or melanised moths $(Biston \ carbonaria)$.
$\Rightarrow$ However,when the collection was carried out from the same area after industrialisation,i.e.,in $1920$,there were more dark-winged moths in the same area,i.e.,the proportion was reversed.
Before industrialisation,thick growth of white-coloured lichen covered the trees. In that background,the white-winged moth survived,but the dark-coloured moths were picked out by predators.
$\Rightarrow$ Lichens can be used as industrial pollution indicators.
$\Rightarrow$ They do not grow in areas that are polluted.
$\Rightarrow$ During the post-industrialisation period,the tree trunks became dark due to industrial smoke and soot.
$\Rightarrow$ Under this condition,the white-winged moth did not survive due to predators,while dark-winged or melanised moths survived.
$\Rightarrow$ Hence,moths that were able to camouflage themselves,i.e.,hide in the background,survived.
$\Rightarrow$ This understanding is supported by the fact that in areas where industrialisation did not occur,e.g.,in rural areas,the count of melanic moths was low.
$\Rightarrow$ This showed that in a mixed population,those that can better adapt,survive and increase in population size.

(N/A) Evolution by natural selection in a true sense started when cellular forms of life with differences in metabolic capabilities originated on Earth.
The essence of the Darwinian theory of evolution is natural selection.
The rate of appearance of new forms is linked to the life cycle or life span of the organism.
Microbes that divide rapidly have the ability to multiply and become millions of individuals within hours.
$A$ colony of bacteria (say $A$) growing on a given medium has built-in variation in terms of its ability to utilize a feed component.
$A$ change in the medium composition would favor only that part of the population (say $B$) that can survive under the new conditions.
In due course of time,this variant population outgrows the others and appears as a new species.
This process can happen within days for microbes.
For the same process to occur in fish or fowl,it would take millions of years because the life spans of these animals are measured in years.
Here,we say that the fitness of $B$ is better than that of $A$ under the new conditions.
Nature selects for fitness based on characteristics that are inherited.
Hence,there must be a genetic basis for being selected and for evolution to occur.
Another way of expressing this is that some organisms are better adapted to survive in an otherwise hostile environment.
Adaptive ability is inherited and has a genetic basis.
Fitness is the end result of the ability to adapt and be selected by nature.
Branching descent and natural selection are the two key concepts of the Darwinian Theory of Evolution.

(A) The observation of moths in England, specifically the $Biston$ $betularia$ (peppered moth), serves as a classic example of $Natural$ $selection$.
Before industrialization in the $1850s$, the white-winged moths were more abundant than dark-winged moths because they were camouflaged against the light-colored lichens on tree trunks.
After industrialization, the tree trunks became dark due to soot, making the dark-winged moths better adapted to survive predation by birds.
This change in the population frequency of the moth variants due to environmental pressure is a direct evidence of $Natural$ $selection$.

(A) The case of the peppered moth $(Biston \text{ betularia})$ is a classic example of natural selection. Before industrialization in England, tree trunks were covered with light-colored lichens. White-winged moths were able to camouflage against this light-colored background, making them less visible to predators. Consequently, they had a higher survival rate compared to dark-winged moths. After industrialization, the soot killed the lichens and darkened the tree trunks, leading to a shift in the population towards dark-winged moths.

(D) Before industrialization,the tree trunks in England were covered with white-colored lichens. Therefore,white-winged moths were better camouflaged and survived,while dark-winged (melanized) moths were easily preyed upon by birds. Thus,in rural areas,white-winged moths were more abundant. After industrialization,the tree trunks became dark due to smoke and soot,and lichens died. This provided a survival advantage to the melanized moths,leading to an increase in their population in industrial areas.