BhamuIntelli Systems LLP

StudyTunnel

Loading content...

Revision Notes & Summary

Top

Chapter 6: Evolution

6.1 Origin of Life

The origin of life on Earth is linked to the origin of the universe and Earth itself.
Chemical evolution, or the formation of biomolecules, is believed to have preceded the first cellular forms of life.
The first cellular life forms likely originated around 2000 million years ago, primarily in water environments.
The theory of biogenesis suggests that life arose from non-living molecules through evolutionary forces.

6.2 Evolution of Life Forms - A Theory

Evolution is the study of the history of life forms on Earth.
Charles Darwin's observations during his voyage on the H.M.S. Beagle led to the conclusion that existing life forms share similarities with ancient life forms.
Extinctions and the emergence of new life forms have occurred throughout Earth's history.

6.3 What are the Evidences for Evolution?

Evidence for evolution includes comparative anatomy, fossils, and comparative biochemistry.
Homology is explained through branching descent, while analogy results from convergent evolution.

6.4 What is Adaptive Radiation?

Adaptive radiation refers to the diversification of a group of organisms into forms filling different ecological niches.

6.5 Biological Evolution

Biological evolution encompasses the changes in species over time through mechanisms such as natural selection.

6.6 Mechanism of Evolution

The Hardy-Weinberg principle states that allele frequencies in a population remain constant from generation to generation, indicating genetic equilibrium.

6.7 Hardy - Weinberg Principle

The principle can be summarized as:
- Allele frequencies are stable.
- The sum of all allelic frequencies is 1.

6.8 A Brief Account of Evolution

Evolutionary history includes the development of modern Homo sapiens from earlier hominids, with significant milestones such as the development of agriculture.

6.9 Origin and Evolution of Man

The evolution of modern humans includes significant developments in brain size, skeletal structure, and cultural practices.

Exercises

Explain antibiotic resistance in bacteria using Darwinian selection theory.
Research recent fossil discoveries or controversies about evolution.
Define the term species clearly.
Trace the components of human evolution, including brain size and dietary preferences.
Investigate self-consciousness in animals other than humans.
List modern-day animals and link them to corresponding ancient fossils.
Practice drawing various animals and plants.
Provide an example of adaptive radiation.
Discuss whether human evolution can be classified as adaptive radiation.
Trace the evolutionary stages of a specific animal, such as the horse.

Multiple Choice Questions

The development of antibiotic resistance in bacteria

The evolution of Darwin's finches on the Galapagos Islands

The extinction of dinosaurs leading to the rise of mammals

The similar body shape of sharks and dolphins

Correct Answer: B

Solution:

Adaptive radiation refers to the rapid evolution of diversely adapted species from a common ancestor. Darwin's finches are a classic example where different species evolved from a common ancestor to exploit different ecological niches on the Galapagos Islands.

Chapter Concept:

Convergent and Divergent Evolution

Life can arise spontaneously from non-living matter.

Life arises only from pre-existing life.

Microorganisms can be generated from non-living organic molecules.

Life originated from spores from outer space.

Correct Answer: B

Solution:

Pasteur's experiment showed that in pre-sterilized flasks, life did not arise from killed yeast unless the flask was exposed to air, indicating that life arises from pre-existing life.

Chapter Concept:

Spontaneous Generation and Its Rejection

Natural selection of moths during industrialization

Development of antibiotic resistance in bacteria

Formation of ozone layer in the early Earth atmosphere

Chemical evolution leading to the formation of amino acids

Correct Answer: B

Solution:

The development of antibiotic resistance in bacteria is an example of evolution by anthropogenic action, as it occurs due to the excessive use of antibiotics by humans.

Chapter Concept:

Anthropogenic Evolution

The age of the earth

The existence of extinct organisms and evolutionary changes over time

The chemical composition of ancient atmospheres

The origin of life from non-living matter

Correct Answer: B

Solution:

Fossils in sedimentary rock layers show extinct organisms and changes in life forms across geological periods, supporting the theory of evolution.

Chapter Concept:

Palaeontological Evidence

Life can originate from non-living matter under specific conditions.

Life arises only from pre-existing life.

Life originated from outer space through panspermia.

Life can spontaneously generate in nutrient-rich environments.

Correct Answer: B

Solution:

Pasteur's experiment showed that life arises only from pre-existing life, as no new organisms appeared in pre-sterilized flasks unless exposed to existing life forms.

Chapter Concept:

Biogenesis

It provided essential nutrients for early life forms.

It blocked harmful UV radiation, allowing life to thrive.

It facilitated the synthesis of complex organic molecules.

It was a source of oxygen for early aerobic organisms.

Correct Answer: B

Solution:

The ozone layer played a crucial role in blocking harmful UV radiation, thereby protecting emerging life forms and allowing them to thrive on Earth.

Chapter Concept:

Origin of Life

A species of bird that lays fewer eggs but ensures all offspring survive to adulthood.

A species of plant that produces a large number of seeds, but only a few germinate and grow to maturity.

A species of fish that can survive in both fresh and saltwater environments.

A species of mammal that migrates to new territories to find food.

Correct Answer: A

Solution:

Reproductive fitness in Darwinian evolution refers to the ability of an organism to leave more progeny. A bird species ensuring all offspring survive to adulthood maximizes its reproductive success, thus increasing its traits in the population.

Chapter Concept:

Reproductive Fitness

Haeckel believed that embryos pass through all adult stages of other species, while von Baer showed that they do not.

Haeckel argued that embryonic development is unique to each species, while von Baer showed universal embryonic stages.

Haeckel focused on the differences in embryonic development, whereas von Baer emphasized similarities.

Haeckel claimed that embryonic stages are irrelevant to evolutionary theory, contrary to von Baer's findings.

Correct Answer: A

Solution:

Haeckel proposed that embryos of different species pass through adult stages of other species, a view that was refuted by von Baer, who showed that embryos do not pass through such stages.

Chapter Concept:

Embryological Evidence and Its Limitation

A species of fish that can swim faster than its predators survives and reproduces more successfully.

A species of bird that sings the loudest attracts the most mates and has the most offspring.

A species of plant that grows taller than others receives more sunlight and produces more seeds.

A species of mammal that can eat a wider variety of foods survives during a food shortage.

Correct Answer: D

Solution:

The concept of 'survival of the fittest' in natural selection refers to the ability of an organism to survive and reproduce in its environment. A mammal that can eat a wider variety of foods is more likely to survive during a food shortage, thus fitting the environment better.

Chapter Concept:

Darwin-Wallace Theory of Natural Selection

Mutations are the only source of genetic variation, while recombination has no effect on evolution.

Recombination creates new alleles, while mutations only rearrange existing genetic material.

Both mutation and recombination introduce genetic variation, providing raw material for natural selection to act upon.

Recombination is more important than mutation in creating genetic diversity because it occurs more frequently.

Correct Answer: C

Solution:

Both mutation and recombination are critical for introducing genetic variation. Mutations can create new alleles, while recombination shuffles existing alleles during gametogenesis, providing diverse genetic combinations for natural selection to act upon.

Chapter Concept:

Mutation and Recombination as Sources of Variation

It states that allele frequencies in a population remain constant unless acted upon by evolutionary forces.

It describes the process of natural selection leading to new species.

It explains the role of genetic drift in speciation.

It predicts the inevitable extinction of species over time.

Correct Answer: A

Solution:

The Hardy-Weinberg principle posits that allele frequencies in a population remain constant from generation to generation in the absence of evolutionary influences, maintaining genetic equilibrium.

Chapter Concept:

Biological Evolution

CH_4

H_2

NH_3

, and water vapour

CO_2

O_2

N_2

, and

H_2O

N_2

O_2

Ar

, and

CO_2

H_2S

CO_2

NH_3

, and

H_2O

Correct Answer: A

Solution:

S.L. Miller used methane (

CH_4

), hydrogen (

H_2

), ammonia (

NH_3

), and water vapour to simulate the conditions of early Earth and observed the formation of amino acids.

Chapter Concept:

Miller-Urey Experiment

Allele frequencies will change rapidly.

Allele frequencies will remain constant.

New alleles will appear spontaneously.

Allele frequencies will fluctuate randomly.

Correct Answer: B

Solution:

In Hardy-Weinberg equilibrium, allele frequencies in a population are stable and remain constant from generation to generation, provided no evolutionary influences act upon the population.

Chapter Concept:

Factors Affecting Hardy-Weinberg Equilibrium

Genetic drift is a random process, while natural selection is directional.

Genetic drift increases genetic variation, while natural selection decreases it.

Genetic drift occurs only in large populations, while natural selection occurs only in small populations.

Genetic drift requires environmental changes, while natural selection does not.

Correct Answer: A

Solution:

Genetic drift is a random process that can cause allele frequencies to change over time, while natural selection is a directional process where certain traits become more common because they confer a survival advantage.

Chapter Concept:

Mechanism of Evolution

Condensation of water vapor followed by rainfall

Melting of polar ice caps

Volcanic eruptions releasing liquid water

Direct formation from the primordial soup

Correct Answer: A

Solution:

As the Earth cooled, water vapor in the atmosphere condensed and fell as rain, filling depressions to form oceans.

Chapter Concept:

Early Earth Atmosphere and Ocean Formation

It demonstrates that allele frequencies change rapidly over time.

It states that allele frequencies remain constant in the absence of evolutionary forces.

It shows that evolution is a directed process.

It explains the mechanism of genetic drift.

Correct Answer: B

Solution:

The Hardy-Weinberg principle states that allele frequencies in a population remain constant from generation to generation in the absence of evolutionary influences such as mutation, selection, or genetic drift.

Chapter Concept:

Evidence for Evolution

Evolution of different species from a common ancestor in a single geographical area.

Migration of species from one continent to another.

Development of similar traits in unrelated species due to similar environmental pressures.

Extinction of species due to climate change.

Correct Answer: A

Solution:

Adaptive radiation refers to the evolution of different species from a common ancestor within a specific geographical area, as seen with the diverse forms of marsupials in Australia.

Chapter Concept:

Australian Marsupial Radiation

The presence of homologous structures in different species.

The existence of analogous structures in unrelated species.

The theory of spontaneous generation.

The absence of fossils in sedimentary layers.

Correct Answer: A

Solution:

Homologous structures, which are anatomically similar but may perform different functions, indicate common ancestry and support the concept of branching descent.

Chapter Concept:

Branching Descent

0.24

0.36

0.48

0.16

Correct Answer: C

Solution:

The frequency of heterozygous individuals (

Aa

) is given by

2pq

. Here,

p = 0.6

and

q = 1 - p = 0.4

. Therefore,

2pq = 2 \times 0.6 \times 0.4 = 0.48

Chapter Concept:

Hardy-Weinberg Principle

It facilitated the spontaneous generation of life from decaying matter.

It provided the conditions necessary for the formation of complex organic molecules from simpler inorganic compounds.

It prevented the formation of organic molecules by maintaining a high concentration of oxygen.

It was irrelevant to the formation of organic molecules.

Correct Answer: B

Solution:

The reducing atmosphere, rich in methane and ammonia, was crucial for the formation of complex organic molecules from simpler inorganic compounds, as it lacked oxygen which would have oxidized these molecules.

Chapter Concept:

Oparin-Haldane Theory of Chemical Evolution

Homo habilis

Homo erectus

Neanderthal man

Australopithecines

Correct Answer: C

Solution:

Neanderthal man had a brain capacity of about 1400 cc, which is larger than Homo habilis (650–800 cc) and Homo erectus (900 cc).

Chapter Concept:

Brain Capacity in Human Evolution

The development of pesticide-resistant insects due to excessive use of pesticides.

The natural adaptation of moths to their environment over centuries.

The gradual change in beak size of finches on the Galapagos Islands.

The extinction of dinosaurs due to climatic changes.

Correct Answer: A

Solution:

Anthropogenic evolution is exemplified by the rapid development of pesticide-resistant insects due to human actions, such as the excessive use of pesticides, which selects for resistant organisms.

Chapter Concept:

Anthropogenic Evolution

No mutations

Random mating

Large population size

High mutation rate

Correct Answer: D

Solution:

A high mutation rate would alter allele frequencies, disrupting Hardy-Weinberg equilibrium. The principle assumes no mutations, random mating, large population size, no gene flow, and no selection.

Chapter Concept:

Hardy-Weinberg Principle

Natural selection favored dark-winged moths in polluted areas due to better camouflage against soot-darkened trees.

Dark-winged moths were genetically engineered to survive in polluted environments.

White-winged moths migrated to unpolluted areas, leaving only dark-winged moths in industrial regions.

Both dark and white-winged moths had equal chances of survival regardless of environmental changes.

Correct Answer: A

Solution:

Industrial melanism is an example of natural selection, where dark-winged moths had a survival advantage in polluted areas due to their ability to blend in with soot-darkened trees, reducing predation.

Chapter Concept:

Industrial Melanism

Stabilizing selection

Directional selection

Disruptive selection

Sexual selection

Correct Answer: C

Solution:

Disruptive selection is occurring because the predator targets the most common, medium-colored beetles, leading to an increase in the frequency of the extreme phenotypes (very dark and very light beetles).

Chapter Concept:

Natural Selection Types

Physical strength

Reproductive success

Longevity

Ability to adapt quickly

Correct Answer: B

Solution:

In Darwinian evolution, 'fitness' refers to reproductive fitness, meaning organisms that are better adapted to their environment leave more progeny, thereby increasing their traits in the population.

Chapter Concept:

Reproductive Fitness

A species of bird develops a thicker beak over generations to crack open hard seeds.

Multiple bird species on an island evolve from a common ancestor, each with a unique beak shape suited to different food sources.

A bird species migrates to a new island and remains unchanged over time.

Two unrelated bird species develop similar beak shapes due to feeding on similar types of seeds.

Correct Answer: B

Solution:

Adaptive radiation is exemplified by multiple species evolving from a common ancestor, each adapting to different ecological niches. In Darwin's finches, different beak shapes evolved to exploit various food sources on the Galapagos Islands.

Chapter Concept:

Darwin’s Finches

Wings of a butterfly and wings of a bird

Forelimbs of whales and bats

Eyes of octopus and mammals

Flippers of penguins and dolphins

Correct Answer: B

Solution:

Forelimbs of whales and bats are homologous structures as they have similar anatomical structures but perform different functions, indicating common ancestry.

Chapter Concept:

Evidence for Evolution

It demonstrated that life originated from outer space.

It showed that amino acids could be synthesized from inorganic compounds under early Earth conditions.

It proved that life could spontaneously generate from non-living matter.

It confirmed the presence of DNA in early life forms.

Correct Answer: B

Solution:

The Miller-Urey experiment was significant because it demonstrated that amino acids, the building blocks of proteins, could be synthesized from inorganic compounds like methane, ammonia, hydrogen, and water vapor under conditions thought to resemble those of early Earth.

Chapter Concept:

Miller-Urey Experiment

Natural selection

Random chance events

Gene flow

Mutation

Correct Answer: B

Solution:

Genetic drift is primarily caused by random chance events that lead to changes in allele frequencies in a population.

Chapter Concept:

Mechanism of Evolution

Fossils provide evidence of extinct organisms and help determine the geological periods in which they existed.

Fossils are only found in igneous rocks and provide no significant information about past life forms.

Fossils are primarily used to study the chemical composition of ancient atmospheres.

Fossils are used to predict future evolutionary changes in modern species.

Correct Answer: A

Solution:

Fossils found in sedimentary rock layers show extinct organisms and indicate the geological periods in which they existed, supporting the theory of evolution by demonstrating changes in life forms over time.

Chapter Concept:

Palaeontological Evidence

They have identical external appearances.

They perform the same function in all species.

They share a similar underlying bone structure due to common ancestry.

They have evolved independently to adapt to similar environments.

Correct Answer: C

Solution:

The forelimbs of whales, bats, cheetahs, and humans are homologous because they share a similar underlying bone structure, including the humerus, radius, ulna, carpals, metacarpals, and phalanges, due to their common ancestry.

Chapter Concept:

Comparative Anatomy and Homology

It is the result of a large population undergoing genetic drift.

It occurs when a small population becomes isolated and forms a new species.

It is the process by which natural selection favors certain traits.

It refers to the mutation of alleles in a population.

Correct Answer: B

Solution:

The founder effect occurs when a small population becomes isolated, leading to genetic drift and potentially forming a new species.

Chapter Concept:

Genetic Drift and Founder Effect

Mutation

Gene flow

Spontaneous generation

Natural selection

Correct Answer: C

Solution:

Spontaneous generation is an outdated theory that was disproven by Louis Pasteur, whereas mutation, gene flow, and natural selection are recognized mechanisms of evolution.

Chapter Concept:

Mechanism of Evolution

Life originated from outer space through spores.

Life arose from non-living organic molecules formed from inorganic constituents under early Earth conditions.

Life was created spontaneously from decaying matter.

Life forms were created as they are today and have remained unchanged.

Correct Answer: B

Solution:

The Oparin-Haldane theory suggests that life originated from non-living organic molecules, formed from inorganic constituents under conditions of high temperature, volcanic storms, and a reducing atmosphere containing methane and ammonia.

Chapter Concept:

Oparin-Haldane Theory of Chemical Evolution

The evolution of marsupials in Australia

The development of antibiotic resistance in bacteria

The formation of coal from ancient ferns

The extinction of dinosaurs

Correct Answer: A

Solution:

Adaptive radiation is exemplified by the evolution of marsupials in Australia, where different species evolved from a common ancestor to occupy various ecological niches.

Chapter Concept:

Speciation and Genetic Variation

Gene flow

Genetic drift

Natural selection

All of the above

Correct Answer: D

Solution:

Speciation can occur due to changes in allele frequencies caused by gene flow, genetic drift, and natural selection, as these processes can lead to the formation of new species.

Chapter Concept:

Speciation and Genetic Variation

Life originated from pre-existing non-living organic molecules.

Life arose from decaying matter such as straw and mud.

Life was brought to Earth by extraterrestrial spores.

Life evolved through natural selection from simple organisms.

Correct Answer: B

Solution:

The theory of spontaneous generation proposed that life arose from decaying matter like straw and mud, which was later rejected by Pasteur's experiments.

Chapter Concept:

Spontaneous Generation and Its Rejection

By evolving into a variety of forms with different adaptations from a common ancestor.

By migrating from South America to Australia and adapting to new environments.

By developing resistance to predators over time.

By interbreeding with placental mammals to create new species.

Correct Answer: A

Solution:

Adaptive radiation in Australian marsupials is exemplified by the diversification of a common ancestral marsupial into various species, each adapted to different ecological niches within Australia, such as the Tasmanian wolf and the kangaroo.

Chapter Concept:

Adaptive Radiation

Allele frequencies change over time due to selection.

Genotype frequencies remain constant across generations.

There is a high rate of mutation.

The population is small and isolated.

Correct Answer: B

Solution:

In Hardy-Weinberg equilibrium, allele and genotype frequencies remain constant across generations in the absence of evolutionary forces.

Chapter Concept:

Hardy-Weinberg Principle

Life can arise spontaneously from non-living matter.

Life comes only from pre-existing life.

Life originated from outer space.

Life began with the formation of organic molecules.

Correct Answer: B

Solution:

Louis Pasteur's experiments showed that life comes only from pre-existing life, thereby rejecting the theory of spontaneous generation.

Chapter Concept:

Spontaneous Generation and Its Rejection

A population of birds develops a mutation that allows them to digest a new type of seed.

A group of deer migrates to a new forest, introducing new alleles into the local deer population.

A species of fish becomes isolated in a new lake, leading to speciation over time.

A plant species develops resistance to a common herbicide through natural selection.

Correct Answer: B

Solution:

Gene flow occurs when alleles are transferred from one population to another, as seen when the migrating deer introduce new alleles into the local population.

Chapter Concept:

Gene Flow and Gene Migration

Random mutations leading to sudden large changes in species.

The survival and reproduction of individuals best suited to their environment.

The inheritance of acquired characteristics over generations.

The gradual accumulation of neutral mutations over time.

Correct Answer: B

Solution:

Darwinian evolution primarily occurs through natural selection, where individuals with traits better suited to their environment tend to survive and reproduce more successfully, passing those traits to the next generation.

Chapter Concept:

Biological Evolution

The allele frequencies will remain constant.

The allele frequencies will change, disrupting the equilibrium.

The allele frequencies will change temporarily but return to equilibrium.

The allele frequencies will increase uniformly for all alleles.

Correct Answer: B

Solution:

A sudden increase in mutation rate introduces new alleles or changes existing ones, leading to a change in allele frequencies. This disrupts the Hardy-Weinberg equilibrium, as the principle assumes no mutation.

Chapter Concept:

Hardy-Weinberg Equation

Random mating

No mutation

Large population size

Gene flow

Correct Answer: D

Solution:

Gene flow, or the migration of individuals between populations, introduces new alleles and changes allele frequencies, disrupting genetic equilibrium.

Chapter Concept:

Hardy-Weinberg Principle

CH_4

H_2

NH_3

, and water vapor

CO_2

O_2

N_2

, and water vapor

H_2O

O_2

N_2

, and

CH_4

NH_3

CO_2

H_2O

, and

O_2

Correct Answer: A

Solution:

In the Miller experiment,

CH_4

H_2

NH_3

, and water vapor were used to simulate the conditions of early Earth, leading to the formation of amino acids.

Chapter Concept:

Origin of Life

Gene migration

Genetic drift

Mutation

All of the above

Correct Answer: D

Solution:

The Hardy-Weinberg equilibrium can be disturbed by several factors including gene migration, genetic drift, mutation, genetic recombination, and natural selection, all of which can lead to changes in allele frequencies and thus evolutionary change.

Chapter Concept:

Gene Pool and Genetic Equilibrium

The development of wings in both bats and birds.

The diversification of Darwin's finches on the Galapagos Islands.

The evolution of different marsupials in Australia from a common ancestor.

The appearance of antibiotic resistance in bacteria.

Correct Answer: A

Solution:

Convergent evolution occurs when unrelated species develop similar traits independently, such as the development of wings in both bats and birds, due to similar environmental pressures.

Chapter Concept:

Australian Marsupial Radiation

The evolution of different species from a common ancestor in a new environment.

The gradual change of a single species over time in response to environmental changes.

The extinction of multiple species due to rapid environmental changes.

The development of similar traits in unrelated species due to similar environmental pressures.

Correct Answer: A

Solution:

Adaptive radiation refers to the process by which a single ancestral species rapidly diversifies into a wide variety of forms adapted to different environments. Darwin's finches evolved different beak shapes to exploit different food sources on the Galapagos Islands.

Chapter Concept:

Darwin’s Finches

Dryopithecus

Ramapithecus

Australopithecines

Homo habilis

Correct Answer: B

Solution:

Ramapithecus is considered more man-like compared to Dryopithecus, which was more ape-like.

Chapter Concept:

Origin and Evolution of Man

Methane (

CH_4

)

Oxygen (

O_2

)

Ammonia (

NH_3

)

Hydrogen (

H_2

)

Correct Answer: B

Solution:

The Miller-Urey experiment simulated early Earth conditions using methane (

CH_4

), hydrogen (

H_2

), ammonia (

NH_3

), and water vapor, but not oxygen (

O_2

), as the atmosphere was reducing and lacked free oxygen.

Chapter Concept:

Miller-Urey Experiment

Mutations

Reproductive fitness

Geological changes

Environmental pollution

Correct Answer: B

Solution:

Darwin's theory emphasizes reproductive fitness as the key factor in natural selection, leading to the emergence of new species over time.

Chapter Concept:

Speciation and Genetic Variation

Oxygen and Nitrogen

Water vapour, Methane, Carbon dioxide, and Ammonia

Hydrogen and Helium

Ozone and Argon

Correct Answer: B

Solution:

The early Earth's atmosphere was composed of water vapour, methane, carbon dioxide, and ammonia, which were released from the molten mass covering the surface.

Chapter Concept:

Early Earth Atmosphere and Ocean Formation

Gene flow

Mutation

Genetic drift

All of the above

Correct Answer: D

Solution:

The Hardy-Weinberg equilibrium can be disrupted by factors such as gene flow, mutation, genetic drift, recombination, and natural selection.

Chapter Concept:

Mechanism of Evolution

The ability to survive environmental changes

The ability to find food

The ability to reproduce and leave more progeny

The ability to avoid predators

Correct Answer: C

Solution:

According to Darwin, 'fitness' in natural selection refers to reproductive fitness, meaning the ability to leave more progeny.

Chapter Concept:

Mechanism of Evolution

Giant molecules such as RNA, proteins, and polysaccharides

Small unicellular organisms

Complex multicellular organisms

Inorganic compounds

Correct Answer: A

Solution:

The first non-cellular forms of life are believed to have been giant molecules such as RNA, proteins, and polysaccharides that existed about 3 billion years ago.

Chapter Concept:

First Non-Cellular and Cellular Life Forms

A population of beetles gradually develops darker coloration over many generations due to predation pressure.

A single beetle is born with an extra pair of wings, allowing it to escape predators more effectively, and this trait spreads rapidly through the population.

A group of beetles migrates to a new environment and slowly adapts to the new conditions over time.

A beetle population experiences a bottleneck event, leading to reduced genetic diversity.

Correct Answer: B

Solution:

Saltation, as proposed by Hugo de Vries, involves large, sudden mutations that can lead to significant evolutionary changes. The birth of a beetle with an extra pair of wings represents such a sudden, large mutation.

Chapter Concept:

Mutation Theory of de Vries

It increases genetic drift.

It causes gene flow.

It stabilizes allele frequencies.

It leads to genetic isolation.

Correct Answer: B

Solution:

Repeated migration causes gene flow, which changes gene frequencies in both the original and new populations.

Chapter Concept:

Gene Flow and Gene Migration

Artificial selection

Convergent evolution

Industrial melanism

Genetic drift

Correct Answer: C

Solution:

The increase in dark-winged moths in industrial areas is an example of industrial melanism, where darker individuals become more common due to better camouflage against polluted backgrounds.

Chapter Concept:

Evidence for Evolution

It shows that all life forms have remained unchanged over millions of years.

It demonstrates that certain life forms are restricted to specific geological time-spans, indicating the emergence of new forms over time.

It proves that life forms were created simultaneously and have not undergone any evolutionary changes.

It indicates that all life forms evolved from a single ancestor at the same time.

Correct Answer: B

Solution:

The study of fossils in different sedimentary layers indicates that life forms varied over time and certain life forms are restricted to specific geological time-spans, supporting the emergence of new forms at different times in earth's history.

Chapter Concept:

Palaeontological Evidence

360

160

600

720

Correct Answer: A

Solution:

According to the Hardy-Weinberg principle, the frequency of the genotype

AA

p^2

. Given

p = 0.6

, the frequency of

AA

0.6^2 = 0.36

. Therefore, the expected number of individuals with genotype

AA

0.36 \times 1000 = 360

Chapter Concept:

Hardy-Weinberg Principle

By causing the extinction of less fit species

By allowing species to evolve and occupy different ecological niches

By reducing genetic variation within a species

By promoting the uniformity of species across different habitats

Correct Answer: B

Solution:

Adaptive radiation contributes to biodiversity by enabling species to evolve and adapt to different ecological niches, leading to a variety of forms from a common ancestor.

Chapter Concept:

Adaptive Radiation

Increase in the population of white-winged moths.

Increase in the population of dark-winged moths.

No change in the population of moths.

Decrease in the population of both white-winged and dark-winged moths.

Correct Answer: B

Solution:

In a polluted environment where tree bark is darkened, dark-winged moths are better camouflaged and thus have a higher survival rate, leading to an increase in their population.

Chapter Concept:

Biological Evolution

Spontaneous generation

Panspermia

Biogenesis

Chemical evolution

Correct Answer: B

Solution:

The theory of panspermia suggests that life on Earth may have originated from spores that traveled through space.

Chapter Concept:

Origin of Life

Mutation Theory suggests evolution occurs through large, sudden changes, while Darwin's theory suggests gradual evolution through small variations.

Mutation Theory emphasizes the role of environmental changes, while Darwin's theory focuses on genetic drift.

Mutation Theory relies on the inheritance of acquired traits, while Darwin's theory relies on natural selection.

Mutation Theory supports the idea of intelligent design, while Darwin's theory is purely naturalistic.

Correct Answer: A

Solution:

Hugo de Vries' Mutation Theory, also known as saltation, proposes that evolution occurs through large, sudden mutations, contrasting with Darwin's idea of gradual evolution through small, heritable variations.

Chapter Concept:

Mutation Theory of de Vries

Wings of bats and wings of birds

Forelimbs of whales and forelimbs of humans

Thorns of Bougainvillea and tendrils of Cucurbita

Eyes of octopus and eyes of mammals

Correct Answer: D

Solution:

Convergent evolution occurs when different species evolve similar traits independently. The eyes of octopus and mammals are analogous structures that evolved independently to perform similar functions.

Chapter Concept:

Convergent and Divergent Evolution

Adaptive radiation

Convergent evolution

Industrial melanism

Genetic drift

Correct Answer: C

Solution:

Industrial melanism is the phenomenon where darker moths became more common than lighter ones due to pollution darkening the trees, providing camouflage against predators.

Chapter Concept:

Evidence for Evolution

It decreases genetic diversity by eliminating rare alleles.

It increases genetic diversity by introducing new alleles into the population.

It stabilizes genetic diversity by maintaining allele frequencies.

It has no effect on genetic diversity.

Correct Answer: B

Solution:

Repeated gene migration introduces new alleles into a population, thereby increasing genetic diversity and potentially altering allele frequencies.

Chapter Concept:

Gene Flow and Gene Migration

Natural selection

Genetic drift

Gene flow

Reproductive isolation

Correct Answer: C

Solution:

Gene flow introduces new alleles into a population, contributing to genetic variation and potentially leading to speciation.

Chapter Concept:

Speciation and Genetic Variation

Ernst Haeckel

Charles Darwin

Karl Ernst von Baer

Alfred Wallace

Correct Answer: C

Solution:

Karl Ernst von Baer disproved the idea that vertebrate embryos pass through adult stages of other animals, which was initially proposed by Ernst Haeckel.

Chapter Concept:

Embryological Evidence and Its Limitation

Dryopithecus

Ramapithecus

Australopithecines

Homo erectus

Correct Answer: C

Solution:

Australopithecines lived in East African grasslands and evidence shows they hunted with stone weapons but essentially ate fruit.

Chapter Concept:

Origin and Evolution of Man

Random mutations that are beneficial in the presence of antibiotics are selected for.

Bacteria acquire resistance through the spontaneous generation of new traits.

All bacteria inherently possess resistance genes that are activated by antibiotics.

Antibiotics cause bacteria to evolve new resistance traits directly.

Correct Answer: A

Solution:

According to Darwinian selection theory, antibiotic resistance in bacteria primarily develops through random mutations that provide a survival advantage in the presence of antibiotics, leading to natural selection of these resistant strains.

Chapter Concept:

Anthropogenic Evolution

Louis Pasteur

Charles Darwin

Gregor Mendel

Hugo de Vries

Correct Answer: A

Solution:

Louis Pasteur's experiment with pre-sterilised flasks demonstrated that life did not arise from non-living matter, supporting the theory of biogenesis.

Chapter Concept:

Biogenesis

The frequency of homozygous dominant individuals

The frequency of homozygous recessive individuals

The frequency of heterozygous individuals

The total allele frequency in the population

Correct Answer: C

Solution:

In the Hardy-Weinberg equation

p^2 + 2pq + q^2 = 1

, the term

2pq

represents the frequency of heterozygous individuals in the population.

Chapter Concept:

Hardy-Weinberg Equation

Genetic drift increases genetic diversity within a population.

Genetic drift has a more pronounced effect in large populations.

Genetic drift can cause allele frequencies to change randomly over time.

Genetic drift is a deterministic process that leads to adaptation.

Correct Answer: C

Solution:

Genetic drift refers to random changes in allele frequencies, which can have a significant impact in small populations. It is a stochastic process and does not necessarily lead to adaptation.

Chapter Concept:

Genetic Drift and Founder Effect

Homo erectus

Neanderthal man

Australopithecines

Homo sapiens

Correct Answer: C

Solution:

Australopithecines lived in East African grasslands, hunted with stone weapons, and primarily ate fruit.

Chapter Concept:

Origin and Evolution of Man

It broke down water molecules into hydrogen and oxygen.

It facilitated the formation of the ozone layer directly.

It caused the immediate cooling of Earth's surface.

It was responsible for the formation of amino acids.

Correct Answer: A

Solution:

UV radiation from the sun broke up water molecules into hydrogen and oxygen, with the lighter hydrogen escaping into space.

Chapter Concept:

Early Earth Atmosphere and Ocean Formation

Mutation

Genetic drift

Gene flow

Natural selection

Correct Answer: B

Solution:

Genetic drift can lead to significant changes in allele frequencies in small, isolated populations, potentially resulting in speciation.

Chapter Concept:

Speciation and Genetic Variation

All existing life forms share common ancestors, but ancestor forms occurred at different geological periods.

Life forms evolve independently without any common ancestry.

All life forms originated simultaneously in the same geological period.

Life forms do not change over time and remain constant.

Correct Answer: A

Solution:

Branching descent suggests that all existing life forms share common ancestors, but these ancestors existed at different geological periods, indicating a divergence over time.

Chapter Concept:

Branching Descent

A small group of birds from a mainland population colonizes an isolated island, leading to a new species with distinct traits.

A large population of insects experiences a sudden drop in numbers due to a natural disaster, reducing genetic diversity.

A population of mammals gradually adapts to a changing climate over thousands of years.

A species of fish develops resistance to a pollutant over several generations.

Correct Answer: A

Solution:

The founder effect occurs when a small group of individuals becomes isolated from a larger population, leading to reduced genetic variation and potentially the formation of a new species. This is exemplified by the colonization of an isolated island by a small group of birds.

Chapter Concept:

Genetic Drift and Founder Effect

Miller-Urey experiment

Pasteur's swan-neck flask experiment

Hershey-Chase experiment

Meselson-Stahl experiment

Correct Answer: B

Solution:

Pasteur's swan-neck flask experiment demonstrated that life does not spontaneously arise from non-living matter, supporting the concept of biogenesis.

Chapter Concept:

Biogenesis

The evolution of different species from a common ancestor in a single geographical area.

The extinction of species due to environmental changes.

The development of similar traits in unrelated species due to similar environmental pressures.

The gradual change of species over millions of years without branching.

Correct Answer: A

Solution:

Adaptive radiation refers to the evolution of different species from a common ancestor in a specific geographical area, as seen with Darwin's finches on the Galapagos Islands.

Chapter Concept:

Biological Evolution

p^2

2pq

q^2

p^2 + q^2

Correct Answer: B

Solution:

The frequency of heterozygous individuals (Aa) in a population is given by

2pq

according to the Hardy-Weinberg principle.

Chapter Concept:

Factors Affecting Hardy-Weinberg Equilibrium

Embryos of all vertebrates pass through adult stages of other animals.

Embryos of different species show similarities only in early stages but do not pass through adult stages of other species.

Embryos of all vertebrates develop functional gill slits that remain in adults of all species.

Embryos of vertebrates show no similarities at any stage of development.

Correct Answer: B

Solution:

Karl Ernst von Baer demonstrated that while vertebrate embryos show similarities in early stages, they do not pass through the adult stages of other species, contradicting Haeckel's earlier claims.

Chapter Concept:

Embryological Evidence and Its Limitation

Development of agriculture

Mastery of fire usage

Creation of pre-historic cave art

Domestication of animals

Correct Answer: C

Solution:

During the Ice Age, modern Homo sapiens developed pre-historic cave art, which is a significant marker of cognitive and cultural evolution.

Chapter Concept:

Origin and Evolution of Man

Stabilizing selection

Directional selection

Disruptive selection

Balancing selection

Correct Answer: C

Solution:

Disruptive selection favors extreme phenotypes at both ends of the distribution curve, leading to the emergence of two distinct phenotypes within a population.

Chapter Concept:

Natural Selection Types

Divergent evolution leads to similar traits in unrelated species, while convergent evolution leads to different traits in related species.

Divergent evolution results in different traits from a common ancestor, while convergent evolution results in similar traits in unrelated species.

Divergent evolution occurs in the same environment, while convergent evolution occurs in different environments.

Divergent evolution is driven by natural selection, while convergent evolution is random.

Correct Answer: B

Solution:

Divergent evolution occurs when two species evolve different traits from a common ancestor due to different environmental pressures, whereas convergent evolution occurs when unrelated species develop similar traits independently due to similar environmental pressures.

Chapter Concept:

Convergent and Divergent Evolution

Stabilizing selection

Genetic drift

Directional selection

Balanced polymorphism

Correct Answer: B

Solution:

Genetic drift, especially in small populations, can lead to significant changes in allele frequencies over generations purely by chance, which could explain the increase in a rare allele.

Chapter Concept:

Factors Affecting Hardy-Weinberg Equilibrium

Stabilizing selection

Directional selection

Disruptive selection

Artificial selection

Correct Answer: C

Solution:

Disruptive selection favors individuals with extreme trait values at both ends of the distribution curve, leading to two peaks in the phenotypic distribution.

Chapter Concept:

Natural Selection Types

They were formed from decaying organic matter.

They were giant molecules such as RNA, proteins, and polysaccharides.

They were simple unicellular organisms.

They were complex multicellular organisms.

Correct Answer: B

Solution:

The first non-cellular forms of life are hypothesized to have been giant molecules like RNA, proteins, and polysaccharides, which existed around 3 billion years ago.

Chapter Concept:

First Non-Cellular and Cellular Life Forms

Panspermia

Spontaneous generation

Chemical evolution

Natural selection

Correct Answer: B

Solution:

Pasteur's experiments dismissed the theory of spontaneous generation, which proposed that life could arise from decaying matter, by showing that life arises only from pre-existing life.

Chapter Concept:

Spontaneous Generation and Its Rejection

Lichens thrive in polluted environments, indicating high levels of industrial activity.

Lichens are sensitive to air pollution and do not grow in polluted areas, indicating cleaner environments.

Lichens change color in response to pollution, providing a visual indicator of air quality.

Lichens produce toxins that deter predators, affecting moth populations.

Correct Answer: B

Solution:

Lichens are sensitive to air pollution and do not grow in polluted areas, making them effective indicators of environmental pollution levels.

Chapter Concept:

Industrial Melanism

Genetic drift

Natural selection

Gene flow

Adaptive radiation

Correct Answer: B

Solution:

The survival of dark-winged moths in polluted areas is an example of natural selection, where the moths with coloration that blends into the soot-darkened trees are less likely to be preyed upon, thus surviving and reproducing more successfully.

Chapter Concept:

Industrial Melanism

They fluctuate randomly over generations.

They remain constant from generation to generation.

They increase steadily over time.

They decrease steadily over time.

Correct Answer: B

Solution:

The Hardy-Weinberg principle states that allele frequencies in a population are stable and remain constant from generation to generation, indicating genetic equilibrium.

Chapter Concept:

Gene Pool and Genetic Equilibrium

Darwin's finches on the Galapagos Islands

The development of antibiotic resistance in bacteria

The formation of the ozone layer

The extinction of dinosaurs

Correct Answer: A

Solution:

Adaptive radiation is exemplified by Darwin's finches, which evolved from a common ancestor to occupy different ecological niches on the Galapagos Islands.

Chapter Concept:

Adaptive Radiation

Forelimbs of a whale and a bat

Wings of a butterfly and a bird

Thorns of Bougainvillea and tendrils of Cucurbita

Flippers of penguins and dolphins

Correct Answer: A

Solution:

Homologous organs have a common ancestry and similar basic structure but different functions. The forelimbs of a whale and a bat are homologous because they share a similar anatomical structure but are adapted for different functions.

Chapter Concept:

Comparative Anatomy and Homology

Miller-Urey experiment

Pasteur's swan-neck flask experiment

Griffith's transformation experiment

Hershey-Chase experiment

Correct Answer: B

Solution:

Louis Pasteur's swan-neck flask experiment demonstrated that life does not spontaneously arise from non-living matter, but rather from pre-existing life. He showed that sterilized broth remained free of life unless exposed to pre-existing microorganisms.

Chapter Concept:

Spontaneous Generation and Its Rejection

Amino acids

DNA

Complex carbohydrates

Lipids

Correct Answer: A

Solution:

In the Miller experiment, amino acids were observed to form when electric discharge was applied to a mixture of

CH_4

H_2

NH_3

, and water vapor at high temperature, simulating early Earth conditions.

Chapter Concept:

Origin of Life

Mutation

Recombination

Both mutation and recombination

None of the above

Correct Answer: C

Solution:

Both mutation and recombination during gametogenesis create genetic variation that can alter allele frequencies and provide raw material for natural selection.

Chapter Concept:

Mutation and Recombination as Sources of Variation

0.24

0.36

0.48

0.16

Correct Answer: C

Solution:

According to the Hardy-Weinberg principle, the frequency of heterozygous individuals (

Bb

) is given by

2pq

, where

p

is the frequency of the dominant allele and

q

is the frequency of the recessive allele. Here,

p = 0.6

and

q = 1 - p = 0.4

. Thus,

2pq = 2 \times 0.6 \times 0.4 = 0.48

Chapter Concept:

Hardy-Weinberg Equation

Survival of the fittest, where fitness is defined by reproductive success.

Survival of the strongest individuals in a population.

Survival of individuals with the largest physical size.

Survival of individuals with the most mutations.

Correct Answer: A

Solution:

Darwin's concept of natural selection emphasizes reproductive fitness, where individuals that are better adapted to their environment reproduce more successfully.

Chapter Concept:

Biological Evolution

The evolution of different species from a common ancestor due to migration to different geographical areas.

The development of similar traits in unrelated species due to similar environmental pressures.

The process by which a single ancestral species rapidly diversifies into a wide variety of forms to exploit different ecological niches.

The gradual change in species over time due to random mutations and natural selection.

Correct Answer: C

Solution:

Adaptive radiation in Australian marsupials refers to the process where a single ancestral species diversified into a wide variety of forms, each adapted to different ecological niches within the Australian continent.

Chapter Concept:

Australian Marsupial Radiation

p^2

q^2

2pq

(p+q)^2

Correct Answer: C

Solution:

In the Hardy-Weinberg equilibrium, the frequency of heterozygous individuals (Aa) is given by

2pq

, where

p

is the frequency of allele A and

q

is the frequency of allele a.

Chapter Concept:

Gene Pool and Genetic Equilibrium

Green beetles are more visible to predators, leading to their increased survival.

Green beetles are better camouflaged in the forest, leading to their increased survival and reproduction.

Green beetles are more attractive to mates, leading to increased reproduction.

Green beetles have a faster growth rate, allowing them to outcompete other beetles.

Correct Answer: B

Solution:

The Darwin-Wallace Theory of Natural Selection suggests that individuals with traits better suited to their environment are more likely to survive and reproduce. In a forest environment, green beetles are better camouflaged, reducing predation and increasing their chances of leaving more progeny.

Chapter Concept:

Darwin-Wallace Theory of Natural Selection

Genetic mutations

Adaptive radiation

Convergent evolution

Artificial selection

Correct Answer: B

Solution:

The diversity in beak shapes among Darwin's finches is a result of adaptive radiation, where the finches evolved from a common ancestor into different forms adapted to various food sources.

Chapter Concept:

Darwin’s Finches

All life forms originated from a single ancestor at the same geological period.

Life forms share common ancestors that existed at different geological periods.

Each species evolved independently without any common ancestors.

Evolution occurs only through spontaneous generation without ancestral lineage.

Correct Answer: B

Solution:

Branching descent refers to the concept that all existing life forms share common ancestors, but these ancestors existed at different geological periods, leading to the diversity of life observed today.

Chapter Concept:

Branching Descent

Wings of a butterfly and wings of a bird

Forelimbs of a whale and wings of a bat

Thorns of Bougainvillea and tendrils of Cucurbita

Flippers of penguins and flippers of dolphins

Correct Answer: C

Solution:

Thorns of Bougainvillea and tendrils of Cucurbita are homologous structures. They have a common evolutionary origin but have diverged to perform different functions.

Chapter Concept:

Comparative Anatomy and Homology

Genetic drift

Natural selection

Gene flow

Mutation

Correct Answer: B

Solution:

Natural selection is the mechanism where individuals with traits better suited to their environment tend to survive and reproduce at higher rates. In this scenario, darker-colored beetles have a selective advantage as they are less visible to predators.

Chapter Concept:

Reproductive Fitness

Enhanced physical strength

Improved tool-making skills

Ability to live in diverse climates

Development of complex language

Correct Answer: B

Solution:

The Neanderthal man had a brain size of 1400cc, which is associated with advanced tool-making skills and cultural practices such as using hides for protection and burying their dead.

Chapter Concept:

Origin and Evolution of Man

Wings of birds and wings of insects

Forelimbs of whales and wings of bats

Fins of fish and flippers of penguins

Eyes of octopus and eyes of mammals

Correct Answer: B

Solution:

The forelimbs of whales and wings of bats are homologous structures, meaning they have a similar anatomical structure due to common ancestry but have evolved for different functions.

Chapter Concept:

Evidence for Evolution

Large population size

No mutation

Random mating

Gene flow

Correct Answer: D

Solution:

Gene flow, or the migration of individuals between populations, can alter allele frequencies and thus lead to a deviation from the Hardy-Weinberg equilibrium.

Chapter Concept:

Factors Affecting Hardy-Weinberg Equilibrium

The development of antibiotic resistance in bacteria

The evolution of Darwin's finches on the Galapagos Islands

The extinction of dinosaurs

The formation of the ozone layer

Correct Answer: B

Solution:

Adaptive radiation is exemplified by Darwin's finches, which evolved into different species with varied beak shapes to exploit different ecological niches on the Galapagos Islands.

Chapter Concept:

Mechanism of Evolution

Wings of butterflies and wings of birds

Forelimbs of cheetahs and forelimbs of whales

Flippers of penguins and flippers of dolphins

Sweet potato and potato

Correct Answer: B

Solution:

Homologous structures arise from divergent evolution, where similar structures evolve in different directions due to adaptation to different environments. The forelimbs of cheetahs and whales have similar anatomical structures but have evolved to serve different functions.

Chapter Concept:

Convergent and Divergent Evolution

It was supported by the experiments of Louis Pasteur.

It proposed that life arises from non-living matter spontaneously.

It is currently the most accepted theory of the origin of life.

It was first proposed by Charles Darwin.

Correct Answer: B

Solution:

The theory of spontaneous generation proposed that life arises spontaneously from non-living matter. However, this theory was disproved by Louis Pasteur's experiments, which demonstrated that life arises from pre-existing life.

Chapter Concept:

Origin of Life

Panspermia

Spontaneous generation

Chemical evolution

Biogenesis

Correct Answer: C

Solution:

The theory of chemical evolution, proposed by Oparin and Haldane, suggests that life originated from pre-existing non-living organic molecules such as RNA and proteins under early Earth conditions.

Chapter Concept:

Origin of Life

Divergent evolution

Convergent evolution

Parallel evolution

Co-evolution

Correct Answer: B

Solution:

Convergent evolution occurs when different species evolve similar traits independently, often because they adapt to similar environments or ecological niches.

Chapter Concept:

Evidence for Evolution

High temperature and volcanic storms

Presence of a reducing atmosphere with methane and ammonia

Abundant oxygen and nitrogen in the atmosphere

Presence of liquid water and carbon dioxide

Correct Answer: A

Solution:

The Oparin-Haldane theory suggests that life arose from non-living organic molecules formed from inorganic constituents under high temperature and volcanic storms.

Chapter Concept:

Oparin-Haldane Theory of Chemical Evolution

Availability of new ecological niches.

Genetic drift in isolated populations.

Competition with similar species.

Sudden environmental changes leading to mass extinction.

Correct Answer: D

Solution:

Sudden environmental changes leading to mass extinction are not typically a driver of adaptive radiation. Adaptive radiation is more commonly driven by the availability of new niches, genetic drift, and competition, allowing species to diversify and adapt to new roles.

Chapter Concept:

Adaptive Radiation

Pasteur's experiment on spontaneous generation.

Darwin's observations on natural selection.

Miller-Urey experiment.

Hershey-Chase experiment on DNA.

Correct Answer: C

Solution:

The Miller-Urey experiment simulated early Earth conditions by creating an electric discharge in a closed flask containing methane, hydrogen, ammonia, and water vapor at 800°C, resulting in the formation of amino acids, thus supporting the Oparin-Haldane theory.

Chapter Concept:

Oparin-Haldane Theory of Chemical Evolution

A closed flask with electric discharge, resulting in the formation of amino acids

An open flask with sunlight exposure, resulting in the formation of proteins

A vacuum chamber with UV radiation, resulting in the formation of nucleic acids

A sealed container with high pressure, resulting in the formation of lipids

Correct Answer: A

Solution:

S.L. Miller used a closed flask with electric discharge in a mixture of

CH_4

H_2

NH_3

, and water vapor at 800°C, leading to the formation of amino acids.

Chapter Concept:

Oparin-Haldane Theory of Chemical Evolution

Gene migration

Genetic drift

Natural selection

Random mating

Correct Answer: D

Solution:

Random mating does not disturb the Hardy-Weinberg equilibrium, whereas gene migration, genetic drift, and natural selection do.

Chapter Concept:

Factors Affecting Hardy-Weinberg Equilibrium

Presence of oxygen-rich atmosphere and low volcanic activity.

Presence of high temperature, volcanic storms, and a reducing atmosphere containing

CH_4

and

NH_3

Presence of a stable climate and abundant liquid water.

Presence of a magnetic field and tectonic plate activity.

Correct Answer: B

Solution:

The chemical evolution theory suggests that the first forms of life arose from non-living organic molecules under conditions such as high temperature, volcanic storms, and a reducing atmosphere with gases like

CH_4

and

NH_3

Chapter Concept:

First Non-Cellular and Cellular Life Forms

The size of the individuals

The reproductive fitness of the individuals

The age of the individuals

The color of the individuals

Correct Answer: B

Solution:

The Darwin-Wallace theory of natural selection states that individuals with better reproductive fitness are more likely to leave more progeny, thus passing on their heritable traits.

Chapter Concept:

Darwin-Wallace Theory of Natural Selection

The wings of bats and birds

The forelimbs of whales and bats

The eyes of octopuses and mammals

The beaks of Darwin's finches

Correct Answer: A

Solution:

Convergent evolution occurs when different species develop similar traits independently. The wings of bats and birds are an example of convergent evolution as they evolved independently to perform the same function of flying.

Chapter Concept:

Convergent and Divergent Evolution

Gradual accumulation of small variations

Sudden large mutations

Natural selection

Environmental changes

Correct Answer: B

Solution:

Hugo de Vries proposed that evolution is primarily caused by sudden large mutations, which he termed as saltation, unlike Darwin's theory of gradual evolution through small heritable variations.

Chapter Concept:

Mutation Theory of de Vries

True or False

Correct Answer: True

Solution:

Homologous structures, such as the forelimbs of mammals, have similar anatomical structures but may perform different functions, indicating a common ancestry and resulting from divergent evolution.

Chapter Concept :

Evidence for Evolution

Correct Answer: True

Solution:

Convergent evolution occurs when different species evolve similar traits independently, often because they adapt to similar environments or ecological niches.

Chapter Concept :

Convergent and Divergent Evolution

Correct Answer: True

Solution:

Darwin's theory of evolution emphasizes natural selection as a mechanism where organisms better adapted to their environment tend to survive and produce more offspring. Branching descent refers to the evolutionary process where new species arise from a common ancestor.

Chapter Concept :

Biological Evolution

Correct Answer: True

Solution:

The Hardy-Weinberg principle describes a state of genetic equilibrium where allele frequencies remain stable in the absence of evolutionary influences. Factors such as mutation, gene flow, genetic drift, recombination, and natural selection can disturb this equilibrium, leading to changes in allele frequencies.

Chapter Concept :

Mechanism of Evolution

Correct Answer: True

Solution:

Adaptive radiation is exemplified by Darwin's finches and Australian marsupials, where species evolved from a common ancestor to adapt to various ecological niches.

Chapter Concept :

Adaptive Radiation

Correct Answer: True

Solution:

The Neanderthal man had a brain size of about 1400cc, which is supported by fossil evidence.

Chapter Concept :

Origin and Evolution of Man

Correct Answer: True

Solution:

The early Earth lacked an atmosphere and was covered by a mixture of gases including water vapor, methane, carbon dioxide, and ammonia, which contributed to the formation of oceans after cooling and precipitation.

Chapter Concept :

Early Earth Atmosphere and Ocean Formation

Correct Answer: True

Solution:

Louis Pasteur demonstrated through careful experimentation that life does not spontaneously arise from non-living matter. He showed that in pre-sterilised flasks, life did not emerge from killed yeast, while in another flask open to air, new living organisms arose from 'killed yeast'. This disproved the theory of spontaneous generation.

Chapter Concept :

Biological Evolution

Correct Answer: True

Solution:

Convergent evolution occurs when different species evolve similar traits independently, often due to similar environmental pressures or ecological niches.

Chapter Concept :

Convergent and Divergent Evolution

Correct Answer: True

Solution:

Speciation is driven by genetic variation which arises from mutation, recombination, gene flow, and genetic drift. These variations are then acted upon by natural selection and differences in reproductive fitness, leading to the emergence of new species.

Chapter Concept :

Speciation and Genetic Variation

Correct Answer: True

Solution:

The Hardy-Weinberg principle states that allele frequencies in a population remain stable and constant from generation to generation unless affected by evolutionary forces.

Chapter Concept :

Hardy-Weinberg Principle

Correct Answer: True

Solution:

Homologous structures are those that have a common evolutionary origin but may serve different functions in modern species. The forelimbs of whales, bats, cheetahs, and humans all share a similar anatomical structure, which suggests they evolved from a common ancestor.

Chapter Concept :

Comparative Anatomy and Homology

Correct Answer: True

Solution:

Homologous structures, such as the forelimbs of mammals like whales, bats, cheetahs, and humans, indicate a common ancestry and are evidence of divergent evolution, where similar structures have evolved to perform different functions.

Chapter Concept :

Evidence for Evolution

Correct Answer: True

Solution:

Louis Pasteur's experiments showed that life does not arise from non-living matter, thereby disproving the theory of spontaneous generation.

Chapter Concept :

Spontaneous Generation and Its Rejection

Correct Answer: True

Solution:

Adaptive radiation is exemplified by Darwin's finches and Australian marsupials, where species evolved from a common ancestor to adapt to various ecological niches.

Chapter Concept :

Adaptive Radiation

Correct Answer: False

Solution:

Biogenesis states that life arises from pre-existing life but does not explain how the first life form originated.

Chapter Concept :

Biogenesis

Correct Answer: True

Solution:

Homologous structures have a common ancestry and similar basic structure but different functions. The forelimbs of whales, bats, cheetahs, and humans share a similar anatomical structure, indicating a common ancestry.

Chapter Concept :

Comparative Anatomy and Homology

Correct Answer: True

Solution:

The Oparin-Haldane theory posits that life arose from non-living organic molecules, which were formed from inorganic constituents under early Earth conditions such as high temperature, volcanic storms, and a reducing atmosphere rich in methane and ammonia.

Chapter Concept :

Oparin-Haldane Theory of Chemical Evolution

Correct Answer: True

Solution:

Natural selection is a process where individuals with traits that are better suited to their environment tend to survive and reproduce more than those with less advantageous traits. This leads to the gradual evolution of species.

Chapter Concept :

Mechanism of Evolution

Correct Answer: True

Solution:

The Miller-Urey experiment successfully simulated early Earth conditions by using a mixture of methane (

CH_4

), hydrogen (

H_2

), ammonia (

NH_3

), and water vapor, subjected to an electric discharge at approximately 800°C, leading to the formation of amino acids.

Chapter Concept :

Miller-Urey Experiment

Correct Answer: True

Solution:

Louis Pasteur demonstrated through experiments that life does not spontaneously arise from non-living matter, but rather comes from pre-existing life.

Chapter Concept :

Origin of Life

Correct Answer: False

Solution:

Homo habilis is considered the first human-like being with a brain capacity between 650-800cc, but they probably did not eat meat.

Chapter Concept :

Origin and Evolution of Man

Correct Answer: True

Solution:

Speciation is a process where new species arise due to genetic variations accumulated through mechanisms like mutation, recombination, gene flow, and genetic drift, which are then acted upon by natural selection and differences in reproductive fitness.

Chapter Concept :

Speciation and Genetic Variation

Correct Answer: True

Solution:

The theory of panspermia posits that life, in the form of spores, was transferred to Earth from other planets, suggesting an extraterrestrial origin of life.

Chapter Concept :

Origin of Life

Evolution

Learning Objectives

Revision Notes & Summary

Chapter 6: Evolution

6.1 Origin of Life

6.2 Evolution of Life Forms - A Theory

6.3 What are the Evidences for Evolution?

6.4 What is Adaptive Radiation?

6.5 Biological Evolution

6.6 Mechanism of Evolution

6.7 Hardy - Weinberg Principle

6.8 A Brief Account of Evolution

6.9 Origin and Evolution of Man

Exercises

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Tips for Success

AI Learning Assistant

Practice Test – MCQs, True/False

Experience the StudyTunnel Method

Step 1: Chapter Practice

Step 2: Term Boss Exam

Step 3: Redemption Arena

Practice, Analyze & Improve 🚀

Multiple Choice Questions

Q1.Which scenario best illustrates adaptive radiation?

Correct Answer: B

Q2.What was the main conclusion of Louis Pasteur's experiment with pre-sterilized flasks and yeast?

Correct Answer: B

Q3.Which of the following is an example of evolution by anthropogenic action?

Correct Answer: B

Q4.What does the study of fossils in sedimentary rock layers primarily provide evidence for?

Correct Answer: B

Q5.In the context of biogenesis, what was the primary conclusion drawn from Pasteur's experiment with pre-sterilized flasks?

Correct Answer: B

Q6.What role did the ozone layer play in the development of life on Earth?

Correct Answer: B

Q7.Which of the following scenarios best illustrates the concept of reproductive fitness in Darwinian evolution?

Correct Answer: A

Q8.How did Haeckel's interpretation of embryological evidence differ from the findings of von Baer?

Correct Answer: A

Q9.Which scenario best illustrates the concept of 'survival of the fittest' as described by the Darwin-Wallace Theory of Natural Selection?

Correct Answer: D

Q10.Which of the following statements best explains the role of mutation and recombination in the process of evolution?

Correct Answer: C

Q11.How does the Hardy-Weinberg principle relate to the concept of genetic equilibrium in a population?

Correct Answer: A

Q12.Which gases were used by S.L. Miller in his experiment to simulate early Earth conditions?

Correct Answer: A

Q13.If a population is in Hardy-Weinberg equilibrium, what can be said about the allele frequencies over generations?

Correct Answer: B

Q14.How does genetic drift differ from natural selection as a mechanism of evolution?

Correct Answer: A

Q15.Which of the following processes led to the formation of oceans on early Earth?

Correct Answer: A

Q16.How does the Hardy-Weinberg principle relate to evolution?

Correct Answer: B

Q17.Which of the following best describes the concept of adaptive radiation as observed in Australian marsupials?

Correct Answer: A

Q18.In the context of branching descent, which evidence supports the idea that life forms have common ancestors?

Correct Answer: A

Q19.According to the Hardy-Weinberg principle, what is the expected frequency of heterozygous individuals in a population if the frequency of allele AAA is p=0.6p = 0.6p=0.6?

Correct Answer: C

Q20.In the context of the Oparin-Haldane theory, what role did the reducing atmosphere play in the origin of life?

Correct Answer: B

Q21.Which of the following hominids had the largest brain capacity?

Correct Answer: C

Q22.Which of the following scenarios best illustrates evolution by anthropogenic action?

Correct Answer: A

Q23.Which of the following conditions is NOT required for a population to be in Hardy-Weinberg equilibrium?

Correct Answer: D

Q24.Which of the following best explains the phenomenon of industrial melanism observed in moths during the industrial revolution?

Correct Answer: A

Correct Answer: C

Q26.According to Darwinian evolution, what does the term 'fitness' primarily refer to?

Correct Answer: B

Q27.Which of the following scenarios illustrates the concept of adaptive radiation as observed in Darwin's finches?

Correct Answer: B

Q28.Which of the following is an example of homologous structures indicating common ancestry?