Evolution NCERT Flashcards
To understand the changes in flora and fauna that have occurred over millions of years on earth, we must have an understanding of the context of ______.
Origin of life
Huge _______________ comprises the universe.
Clusters of galaxies
_______ theory talks of a singular huge explosion unimaginable in physical terms.
Big Bang theory
Origin of universe is explained by __________ theory
Big Bang theory
How many billion years back the earth was formed?
About 4.5 billion years back
Name 4 gases which were released from molten mass covered surface
Water vapour, methane, carbon dioxide and ammonia
The ____________ from the sun broke up water into Hydrogen and Oxygen
UV rays
Early Greek thinkers thought life came in the form of units from outer space called?
Spores
Oparin of Russia and Haldane of England proposed that the first form of life could have come from pre-existing non-living __________________
Organic molecules (e.g. RNA, protein, etc.)
Diverse organic molecules are formed from ________________
inorganic constituents
What were the conditions of early earth?
high temperature, volcanic storms, reducing atmosphere containing CH4, NH3, etc.
Who proposed the theory of chemical evolution?
Oparin of Russia and Haldane of England
Who provided an experimental proof for chemical evolution of life in 1953?
S.L. Miller
The first non-cellular forms of life could have originated ____________ years back
3 billion
___________ are remains of hard parts of life-forms found in rocks.
Fossils
Different-aged rock sediments contain?
fossils of different life forms (who probably died during the formation of the particular sediment).
A study of fossils in different sedimentary layers indicates?
The geological period in which these life forms existed
The study of fossils show evidence for evolution. These evidence are called?
Paleontological evidence
A technique which is used to find the age of a fossil is called?
Radioactive-dating
______________________ for evolution was proposed by Ernst Heckel.
Embryological support
Embryological support for evolution was based upon the observation of -
Certain features during embryonic stage common to all vertebrates that are absent in adult
______________ and ________________ shows similarities and differences among organisms of today and those that existed years ago.
Comparative anatomy and morphology
Whales, bats, Cheetah and human (all mammals) share similarities in the _________________ of forelimbs.
Pattern of bones
_______________ structures perform different functions but they have similar anatomical structure.
Homologous structures
The same structures developed along different directions due to adaptations to different needs of species. This phenomenon is called
Divergent evolution
Give examples of homologous organs in plants.
Thorn and tendrils of Bougainvillea and Cucurbita
Homology indicates common ____________
ancestry
__________________ are not anatomically similar structures though they perform similar functions.
Analogous structures
Give an example of analogous structures.
Wings of butterfly and birds
Analogous structures are a result of -
convergent evolution
Similarities in proteins and genes performing a given function among diverse organisms give clues to _______________________
common ancestry
Man has bred selected plants and animals for agriculture, horticulture, sport or security. This type of selection is called
Artificial selection
The classical example of natural selection is -
Melanised moth
___________ can be used as industrial pollution indicators as they do not grow in polluted areas.
Lichens
Evolution is a stochastic process based on:-
chance events in nature and chance mutation in the organisms
Small black birds (well known for their remarkable diversity in beak form) found in Galapagos Island are called?
Darwin’s Finches
From the original seed-eating features, many other forms with altered beaks arose, enabling them to become _________________ and _______________________
insectivorous; vegetarian finches
The process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography is called?
Adaptive radiation
Give an example of adaptive radiation?
Australian marsupials
Within the Australian Island continent, a number of marsupials, each different from the other evolved from an ______________
ancestral stock
Give an example of convergent evolution?
Flippers of Penguins and Dolphins.
The two key concepts of Darwinian Theory of Evolution are-
Branching descent and natural selection
Lamarck’s theory of evolution is based on the principle that-
Evolution of life forms had occurred but driven by use and disuse of organs.
The novelty of _________ was: He asserted that variations, which are heritable and which make resource utilisation better for few (adapted to habitat better) will enable only those to reproduce and leave more progeny
Darwin
Hugo deVries work was based on?
evening primrose (Oenothera lamarckiana)
The term used for single step large mutation is?
Saltation
____________ is a specific position on a chromosome where a particular gene is located.
Locus
We can find out the frequency of occurrence of alleles of a gene or a locus by using _______________________
Algebraic equations
What does the Hardy-weinberg principle predict?
It predicts that allele frequencies in a population are stable and is constant from generation to generation
_____________________ is the condition of an allele or genotype in a gene pool (such as a population) where the frequency does not change from generation to generation
genetic equilibrium
What are the factors known to affect Hardy weinberg principle?
Gene migration or gene flow, genetic drift, mutation, genetic recombination and natural selection
The movement of genes from one group of organisms to another is called
Gene migration
______________ is the transfer of genetic variation from one population to another
Gene flow
When the change in frequency of allele occurs in a small population by chance then it is called
Genetic drift
The original drifted population becomes founders and the effect is called?
Founder effect
______________ show that pre-existing advantageous mutations when selected will result in observation of new phenotypes
Microbial experiments
Variation due to mutation or variation due to recombination during gametogenesis, or due to gene flow or genetic drift results in?
changed frequency of genes and alleles in future generation
The mechanism of how non-cellular aggregates of giant ____________ could evolve into cells with membranous envelop is not known.
Macromolecules
Invertebrates were formed and active approximately ________________ years ago
500 million
In 1938, a fish caught in South Africa happened to be a ________________ which was thought to be extinct
Coelacanth
____________ evolved into the first amphibians that lived on both land and water
Lobefins
The _______________ evolved into reptiles.
Amphibians
Some land reptiles went back into water to evolve into fish like reptiles probably __________ mya.
200
____________ was the biggest land reptile?
Tyrannosaurus rex (It was about 20 feet in height and had huge fearsome dagger like teeth)
About _______ mya, the dinosaurs suddenly disappeared from the earth.
65 million years ago
How did dinosaurs disappear from the Earth?
We do not know the true reason. Some say climatic changes killed them. Some say most of them evolved into birds.
The first mammals were like _________
Shrews
__________________ animals protect their unborn young inside the mother’s body.
Viviparous
Some mammals live wholly in water. Examples are -
Whales, dolphins, seals and sea cows
Primates were _____________________ and ____________________ that lived 15 million years ago
Dryopithecus and Ramapithecus
Ramapithecus looked more like:-
Man
Dryopithecus looked more like:-
Ape
The brain capacity of homo habilis was measured -
Between 650 to 800 cc.
The brain capacity of Homo erectus was
Around 900cc.
The ____________ man with a brain size of 1400cc lived in near east and central Asia
Neanderthal
Cave paintings by pre-historic humans can be seen at?
Bhimbetka rock shelter in Raisen district of Madhya Pradesh
On which continent Homo sapiens arose?
Africa
_______________ is the study of history of life forms on earth.
Evolutionary Biology
When we look at stars on a clear night sky we are, in a way, looking back in _______.
time
Stellar distances are measured in _________.
light years
When we see objects in our immediate surroundings we see them instantly and hence in the ______ time
present
When we see ______ we apparently are peeping into the past.
stars
The _________ is considered a unique event in the history of universe.
origin of life
Compared to universe, the earth itself is almost only a ______ .
speck
The universe is almost _________ years old
20 billion
Galaxies contain stars and clouds of _____ and _______.
gas, dust
Name two gases that formed after temperature came down due to expansion of universe.
Hydrogen and Helium
The gases condensed under __________ and formed the galaxies of the present day universe.
gravitation
Earth is present in which galaxy?
Milky way
There was no __________ on early earth.
atmosphere
Oxygen combined with _________ and ______ to form water, CO2 and others
ammonia , methane
As it cooled, the water vapor fell as rain, to fill all the __________ and form oceans
depressions
Life appeared _______ million years after the formation of earth, i.e., almost _____ billion years back
500, four
‘___________’ is still a favourite idea for some astronomers
Panspermia
Which theory proposed that life came out of decaying and rotting matter like straw, mud, etc?
Theory of spontaneous generation
__________ by careful experimentation demonstrated that life comes only from pre-existing life.
Louis Pasteur
In pre-sterilised flasks, life did not come from killed yeast while in another flask open to air, new living organisms arose from ‘killed yeast’. This experiment disproved which theory?
Spontaneous generation theory
When S.L Miller created electric discharge in a closed flask containing CH4, H2, NH3 and water vapour at 800oC, he observed formation of __________
amino acids
In similar experiments others observed, formation of sugars, nitrogen bases,_________ and ______.
pigment,fats
We have no idea about how the first __________ metabolic capsule of life arose.
self replicating
The first cellular form of life did not possibly originate till about __________ years ago
2000 million
The first cellular form of life were probably _________.
single-cells
During early stage of evolution, all life forms were in _______ environment only
water
The first form of life arose slowly through evolutionary forces from _______ molecules.
non-living
Conventional religious literature tells us about the ________________.
theory of special creation
The theory of special creation has __________ connotations.
three
According to theory of special creation, ________ was always the same since creation and will be the same in ________ also.
diversity, future
According to theory of special creation, earth is about _________ years old.
4000 years
All the ideas of theory of special creation were strongly challenged during the _________ century.
nineteenth
Charles Darwin made observations during a sea voyage in a sail ship called ____________ round the world.
H.M.S. Beagle
Charles Darwin concluded that existing living forms share ____________ to varying degrees not only among themselves but also with life forms that existed ________ of years ago.
similarities, millions
There had been __________ of different life forms in the years gone by.
extinctions
New forms of life arose at different periods of history of ________.
earth
There has been ___________ evolution of life forms.
gradual
Any population has built in variation in _____________.
characteristics
Those characteristics which enable some to survive better in natural conditions (climate, food, physical factors,etc.) would ___________ others that are less-endowed to ___________ under such natural conditions
outbreed, survive
The fitness, according to Darwin, refers ultimately and only to __________ fitness.
reproductive
Those who are better _________ in an environment, leave more progeny than others.
fit
Those who are better fit in an environment will ________ more and hence are ________ by nature.
survive, selected
Darwin implied ____________ as a mechanism of evolution.
natural selection
___________, was a naturalist who worked in Malay Archipelago.
Alfred Wallace
All the existing life forms share similarities and share common _________.
ancestors
The geological history of earth closely correlates with the _________ history of earth.
biological
A common permissible conclusion is that earth is very old, not _________ of years as was thought earlier but __________ of years old.
thousand, billions
Evidence that __________ of life forms has indeed taken place on earth has come from many quarters
evolution
Rocks form sediments and a cross-section of ___________ indicates the arrangement of sediments one over the other during the long history of earth.
earth’s crust
The embryos of all vertebrates including human develop a row of ___________ gill slit just behind the head.
vestigial
Gill slits are functional organ only in ______ and not found in any other adult _____________.
fish, vertebrates
_________________ disapproved embryological support for evolution.
Karl Ernst von Baer
Karl Ernst von Baer noted that embryos never pass through the _____ stages of other animals.
adult
Though forelimbs perform different functions in animals, they have similar ___________ structure
anatomical
Homologous organisms have humerus,_________, ulna, carpals, metacarpals and _________ in their forelimbs
radius, phalanges
Other examples of homolgy are vertebrate _______ or _______.
hearts, brains
Crocodiles and birds are living modern day counterpart of _____________.
dinosaurs
Homology is based on ________ evolution.
divergent
Convergent evolution results in _______structures evolving for the _____ function and hence having similarity.
different , same
Other examples of analogy are the eye of the __________ and of mammals or the ________ of Penguins and Dolphins
octopus, flippers
It is the similar habitat that has resulted in selection of similar ___________ features in _________ groups of organisms but toward the same function:
adaptive, different
Sweet potato (__________ modification) and ________ (stem modification) is another example for analogy.
root, potato
_____________ similarities point to the same shared ancestry as structural similarities among diverse organisms.
Biochemical
The intensive breeding programme has created breeds that differ from other breeds (e.g., dogs) but still are of the same______.
group
Man could create new breeds within ________ of years
hundreds
The classical example of natural selection comes from which country?
England
In a collection of moths made in 1850s, there were more _________ moths on trees than dark-winged or ________ moths.
white-winged, melanised
After industrialisation, i.e., in 1920, there were more _________ moths in the same area, i.e., the proportion was __________.
dark-winged, reversed
Predators will spot a moth against a _________ background.
contrasting
During post-industrialisation period, the tree trunks became _______ due to industrial ______ and soots
dark, smoke
When the tree trunks became dark, the __________ did not survive due to predators, dark-winged or _________ moth survived
white-winged moth, melanised
Before industrialisation set in, thick growth of almost __________ lichen covered the trees
white-coloured
When thick growth of almost white-coloured lichen covered the trees - in that background the ________ moth survived but the dark-coloured moth were picked out by ________.
white winged, predators
Moths that were able to ___________ themselves, i.e., hide in the background, survived.
camouflage
In areas where industrialization did not occur, e.g., in rural areas, the count of _______ moths was low.
melanic
In a __________ population, those that can better-adapt, survive and increase in population size.
mixed
No ________ is completely wiped out.
variant
Excess use of herbicides, pesticides, etc., has only resulted in selection of _________ varieties in a much lesser time scale.
resistant
Due to employment of antibiotics or drugs against eukaryotic organisms/cell, resistant organisms/cells are appearing in a time scale of _________ and not ________.
months or years, centuries
Evolution is not a directed process in the sense of _________.
determinism
During his journey Darwin went to __________ Islands where he observed an amazing _________ of creatures.
Galapagos, diversity
___________ represent one of the best examples of adaptive radiation.
Darwin’s finches
When more than one adaptive radiation appeared to have occurred in an isolated geographical area (representing different habitats), one can call this _________ evolution
convergent
Placental mammals in Australia also exhibit _____________ in evolving into varieties of such placental mammals each of which appears to be ‘similar’ to a corresponding __________.
adaptive radiation, marsupial.
Wolf is a placental mammal which is similar to an australian marsupial _____________.
Tasmanian wolf
___________ is a placental mammal which is similar to an australian marsupial Tasmanian tiger cat.
Bobcat
Flying squirrel is a placental mammal which is similar to an australian marsupial _____________.
Flying phalanger
Lemur is a placental mammal which is similar to an australian marsupial _____________.
Spotted cuscus
Mouse is a placental mammal which is similar to an australian marsupial _____________.
Mouse
Anteater is a placental mammal which is similar to an australian marsupial _____________.
Numbat
Mole is a placental mammal which is similar to an australian marsupial _____________.
Mole
Australian Marsupials and placental mammals exhibit the phenomenon of ______________ evolution.
convergent
Evolution by natural selection, in a true sense would have started when _________ of life with differences in ________ capability originated on earth.
cellular forms, metabolic
The essence of Darwinian theory about evolution is ____________.
natural selection
The rate of appearance of new forms is linked to the _________ or the ________.
life cycle, life span
Microbes that divide fast have the ability to _________ and become ________ of individuals within hours.
multiply, millions
A colony of bacteria (say A) growing on a given medium has ___________ in terms of ability to utilise a feed component.
built-in variation
A change in the ________ composition for a colony of bacteria would bring out only that part of the population (say B) that can survive under the new conditions.
medium
In due course of time the variant population _________ the others and appears as _____ species in a microbial colony.
outgrows, new
New species can appear in a microbial colony within _______.
days
For a new species to appear in a fish or fowl time taken would be _______ of years as life spans of these animals are in years.
million
Nature selects for _______.
fitness
One must remember that the so-called fitness is based on characteristics which are ___________.
inherited
There must be a _____ basis for getting selected and to evolve.
genetic
Some organisms are better __________ to survive in an otherwise hostile environment.
adapted
Adaptive ability is ________.
inherited
Adaptive ability has a _________ basis.
genetic
Fitness is the end result of the ability to ________ and get ________ by nature.
adapt, selected
Lamarck gave the examples of ________.
Giraffes
According to Lamarck, Giraffes in an attempt to forage leaves on tall trees had to adapt by ________ of their necks.
elongation
According to Lamarck, Giraffes passed on this acquired character of elongated neck to __________ generations.
succeeding
The world we see, inanimate and animate, is only the success stories of ____________.
evolution
When we describe the story of this world we describe evolution as a __________.
process
When we describe the story of life on earth, we treat evolution as a consequence of a process called _______________.
natural selection
We are still not very clear whether to regard __________ and _________ as processes or end result of unknown processes.
evolution, natural selection
It is possible that the work of ____________ on populations influenced Darwin.
Thomas Malthus
Natural selection is based on certain observations which are ________.
factual
Natural resources are limited, populations are stable in size except for ____________.
seasonal fluctuation
Members of a population ______ in characteristics
vary
Even though they look ____________ similar, no two individuals are alike.
superficially
Theoretically population size will grow ____________ if everybody reproduced maximally.
exponentially
Exponential population growth where everyone reproduced maximally can be seen in a growing ___________ population.
bacterial
Population sizes in reality are limited, means that there had been ___________ for resources.
competition
Hence for a period of time, over many generations, survivors will leave more ________.
progeny
When survivors leave more progeny, there would be a change in ____________ characteristic and hence new forms appear to arise.
population
Mendel had talked of inheritable ‘factors’ influencing ___________.
phenotype
Hugo deVries brought forth the idea of _________.
mutations
Mutations are large difference arising _________ in a population.
suddenly
Hugo deVries believed that it is mutation which causes evolution and not the ____________ (heritable) that Darwin talked about.
minor variations
Mutations are random and _____________.
directionless
_____________ variations are small and directional.
Darwinian
Evolution for Darwin was _________, while deVries believed mutation caused __________.
gradual, speciation
In a given population, one can find out the _________ of occurrence of alleles of a gene or a locus.
frequency
Allele frequency is supposed to remain ______ and even remain the same through ____________.
fixed, generations
Sum total of all the allelic frequencies is ____.
one
In a diploid, p and q represent the ___________ of allele A and allele a.
frequency
The probability that an allele A with a frequency of p appears on both the chromosomes of a diploid individual is simply the product of the ___________, i.e., p2.
probabilities
Binomial expansion of (p+q)2 is ______________________.
p2+2pq+q2=1
When frequency measured, differs from expected values, the difference (direction) indicates the extent of _____________.
evolutionary change
Disturbance in genetic equilibrium, or _____________, i.e., change of frequency of alleles in a population would then be interpreted as resulting in evolution.
Hardy- Weinberg equilibrium
When migration of a section of population to another place and population occurs, gene frequencies change in the ________ as well as in the _________ population.
original, new
New genes/alleles are added to the new population and these are lost from the _________.
old population
There would be a gene flow if this ______________, happens multiple times.
gene migration
Sometimes the change in allele frequency is so different in the new sample of population that they become a different ___________.
species
Over few generations, observation of new phenotypes would result in ___________.
Speciation
Natural selection is a process in which _________ variations enabling better survival are enabled to ___________ and leave greater number of progeny.
heritable, reproduce
Coupled to enhance _____________, natural selection makes it look like different population.
reproductive success
Natural selection in which more individuals acquire mean character value is _______________.
stabilisation
When more individuals acquire value other than the mean character value, it is called _____________.
directional change
Disruption occurs when more individuals acquire _____________ value at both ends of the distribution
peripheral character
In case of stabilising selection peak gets __________ and _________.
higher, narrower
Peak shifts in one direction in case of _____________ selection.
directional
Disruptive selection leads to formation of ________ peaks.
two
About _________ million years ago (mya) the first cellular forms of life appeared on earth.
2000
Some of the cellular forms had the ability to release _____________.
oxygen
The reaction in first cellular forms could have been similar to the _________ in photosynthesis.
light reaction
Slowly single-celled organisms became __________ life forms.
multi-cellular
Sea weeds and few plants existed probably around _____________.
320 mya
The first organisms that invaded land were _______.
plants
Plants were widespread on land when ________ invaded land.
animals
About 350 mya, fish with ________ and ______ fins could move on land and go back to water.
stout, strong
Paleozoic era contains __________,_________,___________ and ________ period.
silurian, devonian, carboniferous and permian
The ancestors of tracheophye plants were ____________
chlorophyte ancestors
The ancestors of rhynia- type plants were _____________
tracheophyte ancestors
The ancestors of Psilophyton were _____________
rhynia- type plants
The ancestors of Psilophyton were _____________
rhynia- type plants
Zosterophyllum appeared during ____________ period.
Silurian
Progymnosperms appeared during ___________ period.
Devonian
Seed ferns appeared during ___________ period.
Carboniferous
Arborescent lycopods appeared during _________ period.
Permian
Mesozoic era contains _________, ____________ and __________ periods.
Triassic, jurassic and cretaceous
Herbaceous lycopods, ferns, conifers and cycads appeared during ___________ period.
Jurassic
Sphenopsids, ginkgos, gnetales and dicotyledons appeared during ___________ period.
Cretaceous
___________ era contains tertiary and quaternary period.
Coenozoic
___________ era contains tertiary and quaternary period.
Coenozoic
___________ era contains tertiary and quaternary period.
Coenozoic
___________ era contains tertiary and quaternary period.
Coenozoic
_______________ appeared in quaternary period.
Angiosperms
Seed ferns evolved from _____________
Progymnosperms
Cycads and dicotyledons evolved from ___________
seed ferns
Gnetales, Ginkgos, ferns and conifers all evolved from________________.
Psilophyton
Lobefins were ancestors of modern day ____ and _____________.
frogs, salamanders
Reptiles laid __________ eggs which do not dry up in sun unlike those of amphibians.
thick-shelled
In the next 200 millions years or so, __________ of different shapes and sizes dominated on earth.
reptiles
Giant ferns (pteridophytes) were present but they all fell to form ____________ slowly.
coal deposits
Synapsids appeared around ___________ mya.
300 mya
Pelycosaurs, Thecodonts and Therapsids are all ___________.
extinct
Extinction of thecodonts occurred ______ mya.
250
Therapsids became extinct in ___________ period.
Jurassic
Dinosaurs became extinct between which two period?
Cretaceous and Tertiary
Early reptiles became extinct around ________ mya.
350
____________ went back into water to evolve into fish like reptiles.
Ichthyosaurs
Tyrannosaurus rex was about _________ in height and had huge fearsome dagger like ______.
20 feet, teeth
When reptiles came down, _________ took over this earth.
mammals
There were in _____________ mammals resembling horse, hippopotamus, bear, rabbit, etc.
South America
Due to ____________, when South America joined North America, these animals were overridden by North American fauna.
continental drift
Due to the continental drift pouched mammals of __________ survived because of lack of competition from any other mammal.
Australia
The most successful story is the evolution of man with __________ skills and _______________.
language, self-consciousness
Dryopithecus and Ramapithecus were _____ and ______ like gorillas and chimpanzees.
hairy, walked
Few fossils of man-like bones have been discovered in ________ and _________
Ethiopia, Tanzania
About _______, man-like primates walked in eastern Africa.
3-4 mya
Man-like primates were probably not taller than _______ but walked ________.
4 feet, up right
Two mya, ____________ probably lived in East African grasslands.
Australopithecines
Australopithecines hunted with ___________ but essentially ate fruit.
stone weapons
Homo habilis probably did not eat ________.
meat
Fossils discovered in Java in 1891 revealed the next stage, i.e., ___________ about 1.5 mya.
Homo erectus
____________ probably ate meat.
Homo erectus
The ____________ man with a brain size of 1400cc lived in near east and central Asia
Neanderthal
The Neanderthal man lived in near east and central Asia between ______________ years back.
1,00,000-40,000
Neanderthal man used ______ to protect their body and buried their _______.
hides, dead
During ice age between ____________ years ago modern Homo sapiens arose.
75,000-10,000
Pre-historic cave art developed about ___________ years ago.
18000
Agriculture came around ____________ years back and ________ settlements started.
10,000, human
The skull of baby chimpanzee is more like adult _______ skull than adult __________ skull.
human, chimpanzee
