WBBSE Solutions For Class 10 Life Science And Environment Chapter 4 Concepts Of Evolution

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Summary

WBBSE Class 10 Evolution Overview

• Evolution is the change in the heritable characteristics of the organisms over successive generations. Complex organisms are produced from simple organisms through evolution.
• Various concepts and theories are proposed regarding the origin of life, of which the theory of Oparin and Haldane is mostly accepted. Earth formed around 4.6 billion years ago.
• At that time, the temperature of earth was 5000-6000°C and the environment was reducing in nature. Gradually, organic compounds developed from inorganic compounds via a process called chemogeny.
• According to Oparin and Haldane, life originated in the ancient seas, that contained hot water and a large amount of organic monomers and polymers.
• Scientist Haldane named it ‘hot dilute soup! Oparin and Haldane propounded the idea of coacervate, which was described as a colloidal, membrane-bound, organic matter containing particles, formed within a hot dilute soup and acting as a precursor of life.
• Sidney Fox proposed the theory of microsphere and according to him, life originated from microsphere. The first cell or protocell originated about 3.7 billion years ago in the hot, ancient seas.
• In 1953, Miller and Urey conducted an experiment where, in the presence of water vapour, they combined methane, ammonia and molecular hydrogen at the ratio of 2:2:1 and pulsed that in a controlled environment with an electrical discharge.
• The experiment was a success as simple organic molecules, including amino acids, had formed in that set-up, thus supporting the hypotheses of Oparin and Haldane.
• The main events of the evolution of life are-Origin of earth-Origin of life-Origin of unicellular organisms-Origin of photosynthetic bacteria-Origin of multicellular organisms-Origin of aquatic vertebrates-Evolution of plants on land-Origin of four-legged terrestrial vertebrates.

Wbbse Class 10 Life Science Solutions

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Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Long Answer Type Questions

Question 1. Show the major evolutionary events with the help of a chart.
Or,
With the help of arrow signs, show the major evolutionary events as occurred gradually after the origin of life.

Answer:

The major evolutionary events:

Darwin’s Theory of Natural Selection Explained

Question 2. Describe the concept of chemosynthesis of life.

Answer:

Chemosynthesis of life:

Wbbse Class 10 Life Science Solutions

The chemosynthesis of life occurred in four phases. These are described below.

1. Phase 1-Origin of simple organic compounds:

In the primitive ocean, several inorganic substances reacted with each other to synthesize simple organic compounds, like acetylene, methane, ethylene, etc. In these reactions ultraviolet rays, lightning, extreme heat, etc.

supplied the requisite energy. Later, these organic substances reacted with water vapour to synthesize some hydrocarbon compounds, such as acetaldehyde.

2. Phase 2-Synthesis of complex organic compounds:

The interaction of these simple organic compounds later gave rise to complex organic matters, like carbohydrates (glucose, fructose, etc.), fatty acids and glycerol, amino acids (alanine glycine, etc) etc.

These complex compounds then reacted with each other to synthesize more complex and larger organic molecules, like simple proteins, nucleotides and lipids.

Finally, nucleic acids and complex proteins were produced in the hot water of the primitive ocean.

3. Phase 3-Formation of coacervates:

In the course of time, the organic macromolecules interacted to produce numerous spherical, double membrane-bound, divisible, colloidal microparticles, which were denoted as coacervates by Oparin.

According to Oparin and Haldane, these microparticles were composed of several components like proteins, nucleic acids, carbohydrates, etc. which were important for the origin of life on Earth.

Sidney Fox opined that… several protein molecules united in the primitive ocean to produce tiny proteinaceous particles called microspheres. According to him, life originated on Earth from microspheres.

4. Origin of protocells:

Scientists assumed that the tiny coacervates engulfed nucleic acids and proteins from the environment, enlarged in size and finally took the shape of protocells. These protocells are thought to be the earliest forms of life on Earth.

RNA was the genetic material of these protocells. These were heterotrophic in nature. In the course of organic evolution, chemosynthetic and photosynthetic forms of life emerged on Earth.

With the emergence of photosynthetic organisms, free oxygen was liberated into the primitive atmosphere.

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Question 3. What is hot dilute soup? Give a brief description of the ‘biogeny’ of the ‘evolution of life’ on earth.

Answer:

Hot dilute soup:

Before the origin of life on earth, several simple organic compounds reacted with each other to synthesize complex organic matter, like amino acids, nucleotides, lipids, carbohydrates, etc.

All these compounds remained suspended in hot water of the primitive ocean. Scientist Haldane described this mixture as ‘hot dilute soup. Sometimes it is also called ‘prebiotic soup. Scientists assumed that life on earth originated in this ‘hot dilute soup’.

Biogeny or evolution of life on Earth:

About 3.7 billion years back, life originated on Earth in the form of protocells. The successive events during the origin of life on Earth are mentioned below.

1. Origin of protocell:

By the process of chemosynthesis, coacervates were formed in the primitive ocean. Later, nucleic acids and protein molecules fused with coacervates to form protocells.

2. Origin of autotrophs:

The primitive organisms, that evolved from the protocells were chemo-heterotrophs. Later came the chemoautotrophs and then emerged the photosynthetic prokaryotic life forms.

With the emergence of photosynthetic organisms, free oxygen was released into the primitive atmosphere. Thus, the character of the atmosphere changed from reducing to oxidising one.

3. Origin of eukaryotes:

About 1.5 billion years ago, unicellular, aerobic eukaryotes evolved on Earth. In the course of evolution, multicellular complex organisms came into being from those unicellular forms.

Types of Evolutionary Adaptations

Question 4. Explain the important events of organic evolution.

Answer:

Important events of organic evolution:

The whole event, starting from the origin of life on Earth to the ongoing organic evolution, it has always been a very complex process.

By assembling the concepts and theories of different scientists, we have developed some ideas on the origin of life on Earth and the trend of organic evolution, which are mentioned below.

1. Origin of Earth:

Earth is the third planet in the solar system. It has originated from the solar nebula about 4.5 to 5.0 billion years back.

2. Origin of Life:

About 3.5 to 3.7 billion years ago, life originated on Earth. Two scientists, Haldane and Oparin, have put forward a clear idea on the origin of life in the water of primitive oceans by successive reactions among several inorganic and organic chemicals.

3. Origin of unicellular organisms:

The first living forms on earth were the primitive unicellular forms, which were the primitive heterotrophic prokaryotes. From the prokaryotes, emerged the unicellular eukaryotes.

4. Origin of photosynthetic prokaryotes:

From the primitive heterotrophic prokaryotes, there evolved some photosynthetic prokaryotes. With the emergence of photosynthetic forms, the production of free oxygen started and the primitive reducing atmosphere transformed into an oxidising one.

5. Emergence of multicellular organisms:

In the course of evolution, multicellular organisms emerged on Earth. These were more complex and advanced than their ancestors.

6. Emergence of different invertebrates and fish-like vertebrates:

With gradual advancement, different invertebrates came into being. After the emergence of higher invertebrates, there came some fish-like vertebrates.

7. Emergence of terrestrial plants:

Primitive plants originated in water. In the course of evolution, terrestrial plants emerged. These newly arrived terrestrial plants got themselves adapted to this new environment slowly and thereafter several advanced terrestrial plants emerged on Earth.

8. Emergence of terrestrial animals:

While living in an aquatic environment, some fish-like forms have developed some organs suitable for terrestrial living. Gradually some of these forms, for instance; amphibians, rejected the aquatic life and started dwelling on the land.

Later, different advanced terrestrial forms, like mammals and birds, emerged on Earth.

Wbbse Class 10 Life Science Solutions

Question 5. Describe the brief outline of the chemical origin of life mentioning Miller and Urey’s experiment. Similar question, Briefly describes the experiment conducted by Miller and Urey on the origin of life.

Answer:

The experiment of Miller and Urey:

Based on the concept of chemosynthesis of life, proposed by Oparin and Haldane, Stanley Miller and Harold Urey performed an experiment in 1953 in the laboratory of Chicago University.

1. Procedure:

They prepared a highly heat-resistant instrument with two inter-connected chambers of unequal diameters. The larger chamber was fitted with two electrodes and was filled with a mixture of hydrogen, methane and ammonia gases.

The outlet pipe of the larger chamber was fitted with a cooling device and a tap which was used to tap down the contents from it. The smaller chamber was used as a boiler and a connecting pipe was fitted with it to supply vapour to the larger chamber.

Powerful electric sparks were generated in the larger chamber to mimic the lightning-like situation (that prevailed in the primitive atmosphere). The water of the smaller chamber was boiled by heating it externally, thus the newly formed water vapour is pushed into the larger chamber.

The machine was run continuously for one week and the product from the larger chamber was tapped down after condensation.

 

Life Science Class 10 Wbbse

2. Observation:

After analysing the product, scientists found a number of amino acids, viz. glycine, alanine, glutamic acid, aspartic acid, etc. in it.

3. Conclusion:

From the result, Miller and Urey concluded that in the primitive, free oxygen-lacking, reducing atmosphere, different inorganic matter reacted with each other to synthesize organic substances.

In this reaction, heat, lightning, ultraviolet ray and other cosmic rays provided the energy that was needed. The organic matter, thus synthesized, acted as the building blocks of cells and finally helped in the origin of life.

Significance of Miller and Urey’s experiment:

Miller and Urey’s experiment supports the abiogenetic theory of the origin of life. According to this theory, life was originated from abiotic or inorganic substances around 3.7 billion years ago.

Evidence of Evolution in Fossils

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Short Answer Type Questions

Question 1. Define life.

Answer:

Life:

Life is the condition that differentiates a living organism from a non-living object. Life shows the signs of growth, reproduction, metabolic activities, excitability, adaptability, ageing and senescence.

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Question 2. What do you mean by organic evolution? Or, What is meant by evolution?

Answer:

Organic evolution:

Organic evolution is the process of slow and steady changes in the characteristics of organisms. These changes result in to the origin of complex and higher descendent varieties or species from simpler and primitive ancestral types. Organic evolution is the cause of biodiversity on the earth.

Question 3. What do you mean by the cosmogenic origin of life?

Answer:

The cosmogenic origin of life:

Swiss author, Erik Von Daniken, in his number of books, claimed that life was introduced to Earth from other planets of other galaxies. This pseudo-scientific concept is known as the theory of the cosmogenic origin of life.

 

 

Question 4. What is meant by the cyanogen theory of the origin of life on Earth?

Answer:

The cyanogen theory of the origin of life on Earth:

According to German scientist Pflüger, when the earth was cooling down, carbon and nitrogen combined to form a complex compound, named cyanogen.

It is a protein-like compound, which in the course of time produced protoplasm. This concept is known as the cyanogen theory of the origin of life.

Life Science Class 10 Wbbse

Question 5. What is meant by the spontaneous creation of life or abiogenesis?

Answer:

The spontaneous creation of life or abiogenesis:

The Greek philosopher Aristotle and famous Belgian chemist, Van Helmont believed that life has originated on earth spontaneously from non-living matters.

This concept on the origin of life is known as the spontaneous creation of life or abiogenesis or biopoiesis.

Artificial Selection and Its Role in Evolution

Question 6. What is Chemogeny?

Answer:

Chemogeny:

Chemogeny is the origin of life, on earth through the ongoing synthesis of complex compounds by successive chemical reactions of different elements and simpler compounds.

Question 7. How did free oxygen evolve in Earth’s atmosphere?

Answer:

Free oxygen evolve in Earth’s atmosphere:

In primitive Earth, the pioneer life forms were chemoheterotrophs. In the course of evolution, these organisms were gradually transformed into photoautotrophs. These aerobic photosynthetic organisms released free oxygen in the primitive atmosphere by performing photosynthesis.

Question 8. What are coacervates?

Answer:

Coacervates:

According to Alexander Oparin, in the organic compound-rich hot water of the primitive ocean, many spherical colloidal droplets were formed.

These tiny droplets were composed of several amino acids, simple carbohydrates and lipid molecules. He denoted these colloidal droplets as coacervates.

 

Molecular Evidence for Evolution

Question 9. Write down the characteristics of coacervate.

Answer:

The characteristics of coacervate are

1. It is a large organic compound, composed of carbohydrates, amino acids, proteins, etc.
2. Coacervate was covered by a lipid membrane.
3. Coacervate was able to absorb nutrients from the surroundings.

Question 10. What are microspheres?

Answer:

Microspheres:

According to Sidney Fox, in the primitive ocean, many amino acid molecules united to form a double-layered lipid membrane-bound, tiny, divisible, spherical droplets.

These are called microspheres, which are assumed to be the precursor of primitive cells. Sidney Fox opined that life has originated from microspheres, not from coacervates.

Life Science Class 10 Wbbse

Question 11. Write down the characteristics of the microsphere.

Answer:

The characteristics of a microsphere are-

1. Microsphere originates from the polypeptide.
2. Microsphere is more durable than coacervate.
3. Microsphere is covered by a double membrane.
4. It is capable of bud formation and can use ATP as a source of energy.
5. It has self propagative properties.

Question 12. Distinguish between coacervate and microsphere.

Answer:

The distinguishing features between coacervate and microsphere are-

 

Question 13. What are protobionts?

Answer:

Protobionts:

The earliest form of life originated on earth in the primitive ocean in form of a double-layered lipid membrane-bound, organic molecule-containing structure. These primitive rudimentary cell-like structures are called protobionts.

Scientists believe that prokaryotic cells have emerged from these protobionts. Example-Microspheres.

Question 14. What is the RNA world hypothesis?

Answer:

RNA world hypothesis:

A line of thought states that the first genetic material present in the protocell was RNA. Later, in the course of evolution, DNA molecules were formed from RNA by biochemical transformation. This concept is known as the RNA world hypothesis.

Question 15. What are naked genes?

Answer:

Naked genes:

In the second phase of Chermogenesis, a number of free nucleotides joined together to form polynucleotide or nucleic acid chains. These are called naked genes. These naked genes are nothing but the RNA molecules.

Question 16. What are proteinoids?

Answer:

Proteinoids:

At high temperatures and in the presence of ultraviolet rays, many protein molecules denature and form amino acids. With a gradual decrease in temperature, these amino acid molecules polymerise to form tiny protein-like globules, called proteinoids.

Scientists believe that the proteinoids played some role in the origin of primordial cells.

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Question 17. What are the characteristics of protocells?

Answer:

The characteristics of protocells are-

1. Protocell contains nucleic acid.
2. Protocell is covered by a bilayered membrane.
3. Protocell has the ability to produce replicas by division.

Question 18. Write the name of the reactants used and one organic compound formed in the experiment of Miller and Urey in connection with the chemical origin of life.

Answer:

In the experiment of Miller and Urey in connection with the chemical origin of life, the reactants used were methane (CH₄), ammonia (NH₃), hydrogen (H₂) and water vapour (H₂O) experiment was amino acids, viz. glycine, alanine, and the organic compound formed in the glutamic acid, aspartic acid, etc.

 

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Very Short Answer Type Questions Multiple Choice Questions And Answers [Mcq]

Question 1. The theory of the origin of life was first proposed by —

1. Pasteur
2. Oparin
3. Darwin
4. Mendel

Answer: 2. Oparin

Question 2. Scientist Stanley Miller was able to synthesize simple amino acids from a mixture of—

1. H₂, 0₂, N₂ and H₂0
2. H₂, NH₃, CH₄ and water vapour (H₂0)
3. NH₃, CH₄, HCN
4. N₂, NH₃, HCN and 0₂

Answer: 2. H₂, NH₃, CH₄ and water vapour (H₂0)

Question 3. Miller and Urey, in their experiment, were able to synthesize some preliminary constituents necessary for the creation of life. Identify the ones which were amino acids among them—

1. Lactic acid, Acetic acid
2. Urea, Adenine
3. Glycine, Alanine
4. Formic acid, Acetic acid

Answer: 3. Glycine, Alanine

Question 4. The most important organic matter for the origin of life is—

1. Nucleic acid
2. Nucleoside
3. Amino acid
4. Protein

Answer: 1. Nucleic acid

Question 5. The gas which was absent in the environment ^ during the origin of life is—

1. Hydrogen
2. Oxygen
3. Methane
4. Ammonia

Answer: 2. Oxygen

Question 6. Who was the first to disapprove the doctrine of spontaneous generation of life?

1. Louis Pasteur
2. Alexander Oparin
3. Aristotle
4. Miller

Answer: 1. Louis Pasteur

Question 7. The cause of biodiversity on earth is—

1. Metabolism
2. Locomotion
3. Evolution
4. Adaptation

Answer: 3. Evolution

Question 8. Where did life originate on Earth?

1. In Ocean
2. On land
3. In space
4. Under soil

Answer: 1. In  Ocean

Question 9. The cellular organisation appeared first in—

1. Nucleoproteins
2. Coacervates
3. Bionts
4. Protobionts

Answer: 2. Coacervates

Question 10. The chemosynthesis of life was clearly demonstrated by—

1. Lamarck and Darwin
2. Miller and Urey
3. Plato and Dante
4. Starling and Bayliss

Answer: 2. Miller and Urey

Question 11. The gradual development of a modern organisms from primitive ones is called—

1. Variation
2. Evolution
3. Adaptation
4. Behaviour

Answer: 2. Evolution

Question 12. The study of development of an organism in its life-span is called—

1. Organic evolution
2. Ontogeny
3. Mutation
4. Special creation

Answer: 2. Ontogeny

Question 13. Which of the following means—changes in the organisms for a prolonged time?

1. Adaptation
2. Accommodation
3. Evolution
4. Reproduction

Answer: 3. Evolution

Question 14. The term ‘evolution’ was coined by—

1. Lamarck
2. Darwin
3. Hugo de Vries
4. Herbert Spencer

Answer: 4. Herbert Spencer

Question 15. The unit of studying evolution is—

1. DNA
2. RNA
3. Protein
4. Species

Answer: 4. Species

Question 16. Life originated on Earth about

1. 3.7 billion years ago
2. 2.7 billion years ago
3. 1.1 billion years ago
4. 5.5 billion years ago

Answer: 1. 3.7 billion years ago

Question 17. According to the opinion of scientists, the prebiotic environment of the earth that led to the origin of life was like this—

1. Hot dilute soup is the seawater
2. Cold dilute soup in the seawater
3. Cold dilute soup in the river water
4. Hot dilute soup in the groundwater

Answer: 1. Hot dilute soup is the seawater

 

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Answer In A Single Word Or Sentence

Question 1. What is the approximate age of the earth?
Answer: About 4.6 billion years

Question 2. How many years ago did life originate on the earth?
Answer: About 3.7 billion years ago

Question 3. Which was the first nucleic acid on Earth?
Answer: RNA (Ribonucleic acid)

Question 4. In which form was carbon present in the primitive earth?
Answer: In the primitive earth, carbon was present in reduced form as hydrocarbons.

Question 5. Name a few hydrocarbons that were present in the primitive earth.
Answer: Methane, acetylene, ethylene, etc.

Question 6. Which concept states that life has originated from non-living substances?
Answer: The concept of abiogenesis

Evolutionary Mechanisms: Natural Selection vs Genetic Drift

Question 7. What will you call a nucleic acid-carrying coacervate?
Or,
What is formed when coacervate unites with nucleic acid?
Answer: Protocell

Question 8. Which end product did Miller and Urey get from their experiment? Similar question, Write down the names of two amino acids formed in the experiment of Miller and Urey.
Answer: Amino acids, viz. alanine, glycine, etc.

Question 9. Who is known as the father of evolution?
Answer: Charles Darwin

Question 10. Write two reasons of evolution.
Answer:

Two reasons of evolution

Mutation and adaptation

Question 11. What is biogeny?
Answer:

Biogeny

The chain of events, responsible for the origin of life and its evolution, is called biogeny.

Question 12. Who first introduced the concept of coacervate?
Answer: Alexander Oparin and JBS Haldane

Question 13. Who proposed the concept of a microsphere?
Answer: Sidney Fox

 

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Fill In The Blanks

Question 1. The process of emergence of complex organisms from simple ones by slow, continuous and irreversible changes is called ________ evolution.
Answer: Organic

Question 2. According to Greek philosopher ________, living forms have emerged on earth by the transformation of inanimate objects.
Answer: Aristotle

Question 3. The term ‘hot dilute soup’ was coined by ________.
Answer: Haldane

Question 4. The chemical basis of the origin of life is called ________.
Answer: Chemogeny

Question 5. The spherical aggregates of microdroplets of lipids that originated in the ‘hot dilute soup’ are known as ________.
Answer: Coacervates

Question 6. ________ was the aggregate of some large colloidal molecules during the early phase of the origin of life
Answer: Microsphere

Question 7. The first nucleic acid, produced in the primitive ocean was ________.
Answer: RNA

Question 8. Miller and ________ first proved the theory of chemogeny of life in a laboratory.
Answer: Urey

Question 9. The most acceptable theory on organic evolution was proposed by________.
Answer: Darwin

Question 10. The book titled ‘Origin of Life’ was authored by ________.
Answer: Oparin

Question 11. According to Sidney Fox, an organism originates from ________.
Answer: Microsphere

Question 12. The alternative name of hot dilute soup is ________.
Answer: Prebiotic

Question 13. The organic compound formed in the experiment of Miller and Urey was ________.
Answer: Amino acid

Question 14. On earth, life was originated in ________.
Answer: Primitive ocean

 

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life State True Or False

Question 1. Protocells originated by the association of nucleic acid with coacervates.
Answer: True

Question 2. The materials necessary for the origin of life was present on the landmass of the primitive earth.
Answer: False

Question 3. Miller and Urey experimentally proved the chemosynthetic origin of life on Earth.
Answer: True

Question 4. Darwin coined the term ‘evolution.
Answer: False

Stages of Human Evolution

Question 5. Miller proposed the theory of coacervate.
Answer: False

Question 6. The first formed life was photosynthetic.
Answer: False

Question 7. According to some scientists, the dust particles of the universe condensed to from earth.
Answer: True

 

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Match The Columns

1.

Answer: 1. D, 2. F, 3. A, 4. E, 5. C, 6. B

2.

Answer: 1. C, 2. D, 3. B, 4. A, 5. F, 6. G

Common Misconceptions About Evolution

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Find The Odd One Out

Question 1. Amino acid, Fatty acid, Nucleic acid, Glucose
Answer: Nucleic acid

Question 2. DNA, RNA, Protein, Fatty acid
Answer: Fatty acid

Question 3. Acetylene, Methane, Ammonia, Ethylene
Answer: Ammonia

Question 4. Alexander Oparin, JBS Haldane, Jean Baptist Lamarck, Sidney Fox
Answer: Jean Baptist Lamarck

Question 5. CH₄, NH₃, H₂, H₂S
Answer: H₂S

 

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Fill In The Blanks By Looking At The First Pair

Question 1. Coacervate : Alexander Oparin Microsphere:_________
Answer: Sidney Fox

Question 2. Oparin: Coacervate :: Haldane: _________
Answer: Hot dilute soup

Question 3. Protocell formation: Biogeny:: Formation of the compound from inorganic-organic compound: _________
Answer: Chemogeny

 

Chapter 4 Concept Of Evolution Major Evolutionary Events Origin Of Life Among The Four Concepts Given Three Of Them Belong To One Find That

Question 1. Abiogenesis, Coacervate, Microsphere, Hot dilute soup
Answer: Abiogenesis

Question 2. Double membrane covering, Ability to use ATP, Microsphere, Protenoid derivative
Answer: Microsphere

Question 3. Carbohydrate formation, Fat formation, Formation of an organic compound, Amino acid formation
Answer: Formation of organic compound

Question 4. Stages of development of life, Origin of unicellular. organisms, Origin of- photosynthetic bacteria, Evolution of plants on land
Answer: Stages of development of life