NEET Zoology - Evolution Flashcards

Comprehensive vocabulary flashcards generated from the Zoology lecture notes on Evolution, covering key terms, historical theories, evolutionary evidence, numerical figures, and human evolutionary history.

Evolution

Slow, gradual changes that take place in flora and fauna over millions of years.

Big Bang Theory

Theory explaining the origin of the universe $20\text{ Bya}$ via a single, huge explosion from a hot ball-like singularity with high pressure and high temperature.

Light-Year

The distance travelled by light in one year in a vacuum, used to measure distances between planets and stars.

Primitive Earth Atmosphere

A reducing atmosphere present on Earth $4.5\text{ Bya}$ with high temperatures, no ozone layer, and gases like $\text{CO}_2$, $\text{CH}_4$, $\text{NH}_3$, and $\text{H}_2\text{O}$ vapour released by volcanic eruptions.

Theory of Special Creation

Theory proposed by Father Suarez stating that God created life in 6 days, Earth is 4000 years old, and life was created as such and will remain the same.

Theory of Catastrophism

Theory stating that catastrophic events or calamities destroyed existing life and created new life.

Theory of Panspermia

Also known as Cosmozoic or Extra-terrestrial theory; states that life arrived on Earth from other planets in the form of sperms or spores.

Theory of Abiogenesis

Also known as the Theory of Spontaneous Generation; states that life was created spontaneously from non-living matter like mud, grains, and straw.

Theory of Biogenesis

Theory stating that life arises only from pre-existing life, as proven by Louis Pasteur's S-shaped swan-neck flask experiment.

Theory of Chemical Evolution

Most accepted theory proposed by Oparin and Haldane, stating that life originated from inorganic substances forming simple and complex organic compounds under reducing conditions.

Coacervates

First cell-like protobiont structures proposed by Oparin, lacking a defined membrane and unable to reproduce.

Microspheres

Protobiont structures proposed by Sidney Fox, composed of complex protein molecules that were capable of reproduction.

Miller's Experiment

1953 experiment by Stanley Miller and Urey using a spark discharge chamber at $800^\circ\text{C}$ and $75000\text{ V}$ with $\text{CH}_4$, $\text{NH}_3$, $\text{H}_2\text{O}$, and $\text{H}_2$ to form amino acids (Alanine, Aspartic acid, Glycine) after 18 days.

Lamarckism

Theory of Use and Disuse / Inheritance of Acquired Characters proposed by Jean-Baptiste Lamarck, stating that organ development or disappearance depends on usage during an organism's lifetime.

Theory of Germplasm

Theory proposed by August Weismann disproving Lamarckism by showing through 22 generations of tail-cut mice that only changes in germ cells are inherited.

Darwinism

Theory of Natural Selection proposed by Charles Darwin after his sea voyage on HMS Beagle to the Galapagos Islands.

Population Theory

Theory formulated by Thomas Malthus stating that populations grow exponentially but remain stable due to limited resources, leading to competition.

Intraspecific Competition

Competition occurring between members of the same species for limited resources.

Interspecific Competition

Competition occurring between members of different species for limited resources.

Saltation

A single-step large mutation resulting in the formation of a new species in one generation, proposed by Hugo de Vries in his Mutation Theory.

Industrial Melanism

An example of natural selection in England where dark-winged moths became dominant post-industrialisation (1920s) as dark soot-covered tree barks provided camouflage against predators.

Stabilising Selection

Type of natural selection where intermediate or average phenotypes are selected, such as human birth weight of $3-3.3\text{ kg}$.

Directional Selection

Type of natural selection where the population peak shifts in one direction as one extreme phenotype is selected over time (e.g., Industrial Melanism).

Disruptive Selection

Type of natural selection where both extreme phenotypes are selected simultaneously, creating two distinct peaks (e.g., shell color in snails).

Homologous Structures

Anatomical structures with common origin or basic plan but different functions resulting from divergent evolution (e.g., forelimbs of cheetah, bat, whale, human).

Analogous Structures

Anatomical structures with different origins or basic plans that perform similar functions due to convergent evolution (e.g., wings of butterfly and bird; sweet potato and potato).

Biogenetic Law

Theory proposed by Ernst Haeckel stating that 'Ontogeny recapitulates phylogeny', meaning embryonic development repeats the adult stages of ancestors.

Karl Von Baer's Principle

Principle disproving Haeckel's biogenetic law by showing that embryos never pass through the adult stages of other vertebrates.

Hardy-Weinberg Principle

Principle stating that allele frequencies in a large, randomly mating population remain constant across generations in the absence of natural selection, mutation, migration, drift, and recombination ($p^2 + 2pq + q^2 = 1$).

Founder's Effect

A form of genetic drift where a small group breaks away from the original population to colonize a new area, developing into a distinct population with different gene frequencies.

Bottleneck Effect

A form of genetic drift resulting from a sudden drastic reduction in population size due to natural calamities or human activities.

Adaptive Radiation

The evolutionary process where different species originate from a common ancestral form and radiate into different geographical habitats (e.g., Darwin's finches, Australian marsupials).

Coelacanth

A lobe-finned fish caught in South Africa in 1938, previously thought extinct, representing the ancestor of the first land-invading amphibians.

Tyrannosaurus rex

The largest land dinosaur, standing about $20\text{ feet}$ tall with fearsome dagger-like teeth, which disappeared around $65\text{ mya}$.

Archaeopteryx

A fossil serving as a connecting link between reptiles and birds, possessing reptilian traits (teeth, tail) and avian traits (beak, feathers).

Dryopithecus

A hairy, ape-like human ancestor that lived $15\text{ mya}$ and walked like gorillas and chimpanzees.

Ramapithecus

A hairy, man-like human ancestor that lived $15\text{ mya}$ and exhibited the first bipedal movement.

Australopithecus

Human ancestor living in East African grasslands $2-4\text{ mya}$, under $4\text{ feet}$ in height, who used stone weapons and ate fruits.

Homo habilis

First hominid known as the 'able man' or tool maker, possessing a cranial capacity of $650-800\text{ cc}$ and probably not eating meat.

Homo erectus

Human ancestor appearing $1.5\text{ mya}$ (Java Man found in 1891) with an erect posture, cranial capacity of $900\text{ cc}$, who used fire and ate meat.

Neanderthal Man

Prehistoric human living $40,000-100,000\text{ years ago}$ in Central and East Asia with a cranial capacity of $1400\text{ cc}$, who used hides to protect their body and buried their dead.

Cromagnon Man

Extinct human ancestor with a cranial capacity of $1650\text{ cc}$ who created cave art, such as the Bhimbetka cave paintings dating back $18,000\text{ years}$.

Homo sapiens sapiens

Modern humans that arose during the Ice Age ($75,000-10,000\text{ years ago}$) with a cranial capacity of $1350\text{ cc}$.