Chapter – 4: Evolution and Adaptation | Chapter Solution Class 10

Book Name	: Life Science And Environment
Subject	: Life Science
Class	: 10 (Madhyamik)
Publisher	: Santra Publisher Pvt. Ltd
Unit Name	: Evolution and Adaptation (4th Chapter)

Multiple Choice Questions :

Question 1

Which one is the vestigial organ of man?

1. Stomach
2. Pancreas
3. Colon
4. Appendix

Answer

Appendix

Question 2

Who proposed the theory of mutation?

1. Mendel
2. Darwin
3. Lamarck
4. De-Vries

Answer

Hugo de Vries

Question 3

Who proposed the theory of Natural Selection?

1. Lamarck
2. De-Vries
3. Mendel
4. Darwin

Answer

Charles Darwin

Question 4

Who proposed the idea of ‘Inheritance of Acquired Characters’?

1. De-Vries
2. Haldane
3. Darwin
4. Lamarck

Answer

Jean-Baptiste Lamarck

Question 5

Who first used the term “Struggle for existence”?

1. Weismann
2. Mendel
3. Lamarck
4. Darwin

Answer

Charles Darwin

Question 6

Negatively geotropic roots are found in

1. Cactus
2. Sundari
3. Lotus
4. Paddy

Answer

Sundari

Question 7

The number of air-sacs of pigeons are

1. 7
2. 7 pair
3. 9 pair
4. 9

Answer

9

Question 8

The chemosynthetic theory was proposed by

1. Miller & Urey
2. Oparin & Haldane
3. Darwin & Lamarck
4. Weismann & De-Vries

Answer

A.I. Oparin and J.B.S. Haldane

Question 9

Which one is a halophytic plant?

1. Sundari
2. Cactus
3. Lotus
4. None of them

Answer

Cactus

Question 10

In which plant the leaf is modified into the spine?

1. Cactus
2. Mango
3. Sundari
4. Lotus

Answer

Cactus

Question 11

In which animal pneumatic bone is found?

1. Rat
2. Pigeon
3. Man
4. Fish

Answer

Pigeon

Question 12

Origin of life proposed by

1. Darwin
2. Lamarck
3. Oparin & Haldane
4. Mendel

Answer

Alexander Oparin and J. B. S. Haldane

Question 13

Germplasm theory was proposed by

1. Weismann
2. Darwin
3. Lamarck
4. Mendel

Answer

August Weismann

Question 14

How many eggs per day are liberated by roundworm

1. 7,00,000
2. 2,00,000
3. 75,000
4. 50,000

Answer

2,00,000

Question 15

Which animal exhibits the slowest reproductive rate?

1. Tiger
2. Lions
3. Elephant
4. Fox

Answer

Elephant

Question 16

Present day horse is

1. Equus
2. Eohippus
3. Mesohippus
4. Miohippus

Answer

Equus

Question 17

Viviparous seed germination found in

1. Aloe
2. Sundari
3. Cactus
4. Lotus

Answer

Aloe

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Mention True or False :

Question 1

Retia mirabilia is found in cactus.

Answer

True

Question 2

Venus heart is present in fish.

Answer

False

Venus hearts are not present in fish. They are a type of carnivorous plant that is found in the Amazon rainforest.

Question 3

The scientific study of animal behaviour is known as ethology.

Answer

True

Question 4

The writer of ‘Origin of Species’ is Hugo de Vries.

Answer

False

The writer of Origin of Species is Charles Darwin. Hugo de Vries is a Dutch botanist who proposed the theory of mutation.

Question 5

The length and thickness of the third digit of Equus are very stout.

Answer

True

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Column matching :

Question 

Left Column	Right Column
A. Modern horse	(i) Vestigial organ
B. Cactus	(ii) Equus
C. Coccyx	(iii) Bee
D. Waggle	(iv) Thorns

Answer

Left Column	Right Column
A. Modern horse	(ii) Equus
B. Cactus	(iv) Thorns
C. Coccyx	(i) Vestigial organ
D. Waggle	(iii) Bee

Question 

Left Column	Right Column
A. Pectin	(i) Sundari
B. Pneumatophore	(ii) Oval nucleus
C. Camel’s RBC	(iii) Cactus
D. Vivipary	(iv) Pigeon

Answer

Left Column	Right Column
A. Pectin	(i) Sundari
B. Pneumatophore	(iii) Cactus
C. Camel’s RBC	(ii) Oval nucleus
D. Vivipary	(iv) Pigeon

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Very Short Answer (VSA) Type Questions :

Question 1

Who proposed ‘Natural selection theory?

Answer

Charles Darwin proposed the ‘Natural selection theory.’

Question 2

Give an example of a homologous organ.

Answer

The forelimbs of humans, dogs, and bats are examples of homologous organs.

Question 3

Write an example of an analogous organ.

Answer

Wings of birds and bats are examples of analogous organs.

Question 4

In which reptile 4-chambered heart is found?

Answer

Crocodile has a 4-chambered heart.

Question 5

Name the ancestor of Equus.

Answer

Eohippus is the ancestor of Equus.

Question 6

Give an example of a vestigial organ of man.

Answer

The appendix is a vestigial organ of man.

Question 7

Name the fossil of the oldest forefather of Horse.

Answer

Hyracotherium is the fossil of the oldest forefather of Horse.

Question 8

Which plant shows a leaf modified into a spine?

Answer

The Cactus shows a leaf modified into the spine.

Question 9

In which plant breathing root is found?

Answer

Mangrove shows breathing roots.

Question 10

Which plant show a leaf modified into a spine?

Answer

Aloe and cactus show leaves modified into the spine.

Question 11

Who proposed the ‘Origin of life’ concept?

Answer

Alexander Oparin proposed the ‘Origin of life’ concept.

Question 12

Write the proposer of the ‘Microsphere model’?

Answer

Sidney Fox proposed the ‘Microsphere model.’

Question 13

What is Darwinism?

Answer

Darwinism is the theory of evolution proposed by Charles Darwin.

Question 14

Write the average life span of an elephant.

Answer

The average life span of an elephant is 70 years.

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Short Answer (SA) Type Questions :

Question 1

What is adaptation?

Answer

Adaptation is a heritable trait that helps an organism survive and reproduce in its environment. For example, the long neck of the giraffe helps it reach leaves that other animals cannot reach.

Question 2

What is pneumatophore?

Answer

Pneumatophore is a specialized root that grows above the water level in mangrove trees. It helps the tree breathe by providing oxygen to the roots.

Question 3

What is the role of the swim bladder in fish?

Answer

The swim bladder is a gas-filled sac that helps fish maintain their buoyancy. It also helps fish to change their depth in the water.

Question 4

State any two adaptive features of Cactus

Answer

Two adaptive features of cactus are thick, fleshy leaves that store water and spines that protect the plant from predators.

Question 5

Define homologous organ.

Answer

Homologous organs are organs that have a common origin but may have different functions in different organisms. For example, the forelimbs of humans, dogs, and bats are homologous organs.

Question 6

What do you mean by analogous organ?

Answer

Analogous organs are organs that have similar functions but have different origins. For example, the wings of birds and bats are analogous organs.

Question 7

What is natural selection?

Answer

Natural selection is the process by which organisms that are better adapted to their environment are more likely to survive and reproduce. This leads to the evolution of new species over time.

Question 8

What is a vestigial organ?

Answer

A vestigial organ is an organ that has no known function in an organism. They are thought to be the remnants of organs that were once used for a different purpose.

Question 9

What do you mean by ‘Survival of the fittest’?

Answer

“Survival of the fittest” is a phrase that is often used to describe natural selection. It means that the organisms that are best adapted to their environment are more likely to survive and reproduce, passing on their genes to the next generation.

Question 10

Define evolution.

Answer

Evolution is the cumulative change in the characteristics of an organism or a population, occuring slowly and steadily in the course of successive generations resulting in the origin of more complex and modern types of organisms from simpler ancestral forms.

Question 11

What is chemical evolution?

Answer

Chemical evolution is the process by which organic molecules formed from inorganic molecules in the early Earth. These organic molecules eventually gave rise to the first living cells.

Question 12

What is a protocell?

Answer

A protocell is a primitive, simplified, and hypothetical cell-like structure that might have been a precursor to the first living cells on Earth. It is believed to have emerged through chemical processes, potentially leading to the origin of life.

Question 13

Define Lamarkism.

Answer

Lamarckism is a theory of evolution proposed by Jean-Baptiste Lamarck, suggesting that acquired characteristics during an organism’s lifetime can be inherited by the next generation, leading to evolutionary changes.

Question 14

What is neo-Darwinism?

Answer

Question 15

What is divergent evolution?

Answer

Divergent evolution is the process in which closely related species evolve different traits and characteristics over time due to adapting to different environmental conditions or ecological niches.

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Long Answer (LA) Type Questions :

Question 1

Describe the experiment performed by Miller and Urey along with a proper diagram.

Answer

Miller and Urey’s experiment (1953) simulated the conditions of the early Earth’s atmosphere, hypothesized to be reducing (lacking free oxygen). They combined water, methane, ammonia, and hydrogen in a closed system and subjected it to electrical sparks to simulate lightning. After a few days, they observed the formation of various organic compounds, including amino acids, the building blocks of proteins, which are essential for life.

Question 2

Describe the steps of formation of the first cell.

Answer

The steps of formation of the first cell

1. Prebiotic Earth: Early Earth had a reducing atmosphere with gases like methane, ammonia, hydrogen, and water vapour.
2. Formation of Organic Molecules: Simple organic molecules like amino acids and nucleotides formed from inorganic compounds through natural processes.
3. Polymerization: Organic molecules combine to form more complex macromolecules like proteins and nucleic acids.
4. Protocells: Macromolecules self-assembled into protocells with semi-permeable membranes.
5. Metabolism and Reproduction: Protocells developed basic metabolic processes and the ability to replicate.
6. Natural Selection: Protocells with advantageous traits had a selective advantage and evolved over time.
7. Emergence of First Cell: Eventually, protocells evolved into the first primitive cells with fully functional cellular structures.

Question 3

What is Lamarckism? What are the supportive points of Lamarckism?

Answer

Lamarckism is a theory of evolution proposed by Jean-Baptiste Lamarck, suggesting that acquired characteristics during an organism’s lifetime can be inherited by the next generation, leading to evolutionary changes.

The supportive points of Lamarckism

1. The inherent tendency for development in organisms.
2. The capacity of organisms to adapt to their environment.
3. Use and disuse of organs leading to changes.
4. Inheritance of acquired characteristics.
5. Origin of new variations through an organism’s efforts to adapt.
6. Belief in continuous progression and increasing complexity over time.

Question 4

Define neo-Lamarckism. State about the criticism of Lamarckism.

Answer

Neo-Lamarckism is a modern revival of Lamarck’s evolutionary ideas, proposing that acquired characteristics can be inherited, and environmental influences play a significant role in driving evolutionary changes.

Criticism of Lamarckism includes:

1. Lack of Evidence: There is limited empirical evidence supporting the inheritance of acquired characteristics.
2. Mechanism of Inheritance: Lamarck did not provide a clear mechanism for how acquired traits are passed on to the next generation.
3. Contradictory Examples: Some examples cited by Lamarck, like the giraffe’s neck, have alternative explanations through natural selection.
4. Modern Genetics: Neo-Darwinism and the discovery of genetics largely invalidated Lamarck’s ideas.

Question 5

Describe Darwin’s theory of Natural Selection.

Answer

Darwin’s theory of natural selection proposes that in a population, individuals with advantageous traits have a better chance of surviving and reproducing, passing on these traits to their offspring. Over time, this process leads to the accumulation of favourable traits in the population, resulting in the adaptation and evolution of species to their environment. The mechanism of natural selection plays a crucial role in the diversity and complexity of life on Earth.

Question 6

Briefly state the analysis of the reality of Darwin’s theory. What are the limitations of Darwinism?

Answer

Analysis of the reality of Darwin’s theory:

• Darwin’s theory explains how natural selection drives the evolution of species over time.
• It is supported by substantial evidence, including fossil records and observed natural adaptation.

Limitations of Darwinism:

• Lack of understanding of genetic mechanisms during Darwin’s time.
• Incomplete explanation of the origin of new variations.
• Overemphasis on gradualism, not accounting for rapid evolutionary changes.
• Struggle to explain complex traits with no apparent survival advantage.

Question 7

What is neo-Darwinism? What is the difference between Darwinism and neo-Darwinism?

Answer

Neo-Darwinism is an extension of Charles Darwin’s theory of evolution that incorporates modern genetics, emphasizing the role of genetic mutations and natural selection in driving evolutionary changes.

Aspect	Darwinism	Neo-Darwinism
Genetic Mechanisms	Limited understanding of genetics.	Incorporates modern genetics.
Origin of Variation	The origin of variations is not well explained.	Focuses on genetic mutations as the source.
Rate of Evolution	Emphasizes gradualism.	Recognizes punctuated equilibrium.

Question 8

State the palaeontological evidence for the theory of evolution.

Answer

Question 9

Describe the evolutionary stages of the horse.

Answer

Question 10

State about the evolution of the heart of vertebrates. What is a vestigial organ?

Answer

Evolution of the heart in vertebrates:

• Vertebrates’ hearts evolved from simple, tubular structures in early fish to more complex, multi-chambered organs in mammals.
• Fish have a two-chambered heart with a single atrium and ventricle, while amphibians and reptiles have a three-chambered heart with two atria and one ventricle.
• Birds and mammals evolved a four-chambered heart, separating oxygenated and deoxygenated blood, allowing for efficient oxygen transport.

Vestigial organ: A vestigial organ is a structure that has lost its original function through evolution.

Question 11

Describe the embryonic stages of fish to mammals.

Answer

Embryonic stages of fish to mammals:

1. Fish: Fertilization → Cleavage → Blastula → Gastrula with three germ layers → Development of notochord → Formation of organs → Hatching as fish fry.
2. Amphibians: Similar to fish but undergo metamorphosis from aquatic tadpoles to terrestrial adults.
3. Reptiles: Gastrulation → Organogenesis → Development of scales, limbs, and amniotic egg.
4. Birds: Gastrulation → Specialization of features like beaks, wings, and feathers within the egg.
5. Mammals: Similar to birds but viviparous → Placenta formation → Differentiation of tissues and specialized organ development → Live birth.

Question 12

Briefly describe the survival strategies of adaptation.

Answer

Survival strategies of adaptation:

1. Camouflage: Blending in with the environment to avoid predators or prey.
2. Mimicry: Resembling another organism or object for protection or predation.
3. Hibernation: Entering a dormant state to conserve energy during harsh conditions.
4. Migration: Moving to different regions to find better resources or escape unfavourable conditions.
5. Asexual Reproduction: Reproducing without a mate to ensure survival in isolated or challenging environments.

Question 13

What is adaptation? Why adaptation is the key criterion in the promotion of evolution?

Answer

Adaptation is the process by which organisms develop specific traits or characteristics that allow them to better survive and reproduce in their environment. These adaptations arise through genetic variation within a population, and over time, the traits that confer advantages become more prevalent, leading to the evolution of the species.

Adaptation is a key criterion in the promotion of evolution because:

1. Survival Advantage: Adaptations increase an organism’s chances of survival in its specific environment. Individuals with advantageous traits are more likely to survive and pass on those traits to their offspring.
2. Reproductive Success: Adaptations that improve an organism’s ability to find mates or produce more offspring lead to increased reproductive success. This contributes to the propagation of favourable traits in the population.
3. Species Diversification: Different environments present various challenges, and organisms must adapt to exploit available resources. This diversity of adaptations leads to the emergence of new species over time.

Question 14

State about the morphologic adaptive features of cactus.

Answer

Morphologic adaptive features of cactus:

1. Succulent stems and leaves store water to survive in arid environments.
2. Reduced leaf surface area minimizes water loss through transpiration.
3. A thick waxy cuticle prevents evaporation and conserves water.
4. Spines instead of leaves reduce surface area and protect against herbivores.
5. The deep root system absorbs water from deep in the soil to cope with drought conditions.

Question 15

What is the role of the swim bladder in fish and air sacs in birds?

Answer

Swim bladder in fish:

• Buoyancy control: It helps fish regulate their depth in the water column by adjusting the amount of gas (usually oxygen) in the swim bladder.
• Maintains neutral buoyancy: By controlling the gas volume, fish can stay suspended at a specific depth without exerting much energy for swimming.

Air sacs in birds:

• Oxygen exchange: Air sacs act as a reservoir, allowing continuous one-way airflow through the lungs, ensuring efficient oxygen exchange during both inhalation and exhalation.
• Enhanced respiration: Air sacs enable a constant supply of fresh oxygenated air, improving the efficiency of oxygen transport and facilitating high metabolic demands during flight.

Question 16

Briefly describe the salt adaptation in Sundari.

Answer