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Lamarck's Theory of Evolution

15 questions

All types15Multiple choice9True / False4Matching2
Question 1Question →

Which of the following statements best describes the primary mechanism proposed by Jean-Baptiste Lamarck to explain evolutionary change in organisms?

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Answer: Organs that are used extensively become larger and stronger during an organism's lifetime, and these acquired changes are inherited by its offspring.

Answer

Lamarck proposed that organs developed or altered during an organism's lifetime through use or disuse are directly transmitted to the next generation.
Lamarck's theory of evolution is founded on the concept that an organism can modify its physical structures through frequent use or disuse in response to environmental demands, and that these acquired somatic modifications are passed to its descendants.

Step-by-Step Solution

1
Identify the core postulates of Lamarckism.
Lamarck's theory relies on two main ideas: (1) Use and disuse of organs causes them to strengthen/grow or shrink/atrophy during an individual's lifetime, and (2) Inheritance of acquired characteristics allows these somatic changes to be passed down.
Understanding Lamarck's specific historical model differentiates it from Darwinism and modern genetic theory.
2
Evaluate the option that matches Lamarck's mechanism.
The statement regarding organ growth through extensive use and the inheritance of these somatic modifications directly matches Lamarck's theory.
Lamarck believed environmental need drove somatic changes that were subsequently inherited.

Key Concept

Law of Use and Disuse and Inheritance of Acquired Characteristics
Question 2Question →

According to Jean-Baptiste Lamarck's theory of evolution, physical modifications developed by an organism during its lifetime in response to environmental demands are directly transmitted to its offspring. Is this statement true or false?

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Answer: True

Answer

True. Lamarck's theory posits that acquired phenotypic changes gained during an individual's lifetime are passed down to offspring.
The statement accurately reflects Lamarck's hypothesis, which held that environmental conditions trigger specific needs in an organism, prompting structural adaptations through use or disuse that are subsequently inherited by offspring.

Step-by-Step Solution

1
Analyze the core assertion made in the statement regarding evolutionary change.
The statement asserts that traits acquired during an organism's lifetime due to environmental interaction are inherited by progeny.
Identifying the central claim is necessary to evaluate which historical evolutionary theory it reflects.
2
Compare the claim against the classic postulates of Jean-Baptiste Lamarck.
Lamarck's theory relies on two primary principles: the law of use and disuse, and the inheritance of acquired traits.
Lamarck explicitly argued that organs change with use/disuse and that these structural alterations are directly transmitted to future generations.

Key Concept

Lamarck's Principle of Inheritance of Acquired Characteristics
Question 3Question →

In an experiment designed to test a fundamental principle of evolution, a scientist cut off the tails of mice for twenty-two consecutive generations. Despite this continuous physical modification, all offspring in the twenty-third generation were born with tails of normal length. Which postulate of Lamarck's theory of evolution was directly disproved by the outcome of this experiment?

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Answer: Organisms inherit somatic modifications acquired by their parents during their lifetime.

Answer

Organisms inherit somatic modifications acquired by their parents during their lifetime.
August Weismann's experiment directly refuted Jean-Baptiste Lamarck's concept of the inheritance of acquired characteristics. Because surgical removal of tails affects only somatic cells and not germ cells (sperm and egg), the genetic code governing tail development remained unaltered across generations.

Step-by-Step Solution

1
Analyze the experimental setup and results.
Removing tails surgically for multiple generations represents an acquired somatic change, but offspring continued to inherit normal tails.
Acquired physical changes affect body (somatic) cells rather than germ cells.
2
Relate the empirical evidence to Lamarckian postulates.
Lamarck asserted that traits acquired during an organism's lifetime could be inherited by subsequent generations.
August Weismann's tail-cutting experiment demonstrated that changes to somatic tissues are not inherited, thus disproving the inheritance of acquired characteristics.

Key Concept

Debunking the Inheritance of Acquired Characteristics (Weismann's Germ Plasm Theory)
Estimated Time:1m 0s
Question 4Question →

Jean-Baptiste Lamarck proposed that physical characteristics acquired by an adult organism through the frequent use or disuse of its organs can be directly transmitted to the next generation.

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Answer: True

Answer

The statement is True. Lamarck's theory asserts that somatic modifications acquired during an individual's lifetime due to environmental adaptation and organ use are inherited by offspring.
The statement is True because Jean-Baptiste Lamarck hypothesized that traits acquired by an organism during its lifetime through environmental influence and organ usage are passed down to subsequent generations.

Step-by-Step Solution

1
Identify the core evolutionary mechanism described in the stem.
The statement describes the passage of phenotypic modifications acquired during an organism's life to its descendants.
Understanding the specific mechanism is required to evaluate historical evolutionary hypotheses.
2
Evaluate whether this concept matches Lamarck's postulates.
Lamarckism is specifically defined by the Law of Use and Disuse and the Law of Inheritance of Acquired Characteristics.
Since the stem accurately restates Lamarck's second postulate, the statement is True.

Key Concept

Inheritance of Acquired Characteristics in Lamarckism
Question 5Question →

A researcher observed that waterbirds developed broader webbed feet over their individual lifetimes through constant stretching while swimming, and asserted that their offspring inherited these enlarged webs directly. Which evaluation best critiques this assertion according to modern biological principles?

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Answer: The assertion relies on the inheritance of acquired characteristics, which is invalid because somatic modifications caused by environmental use do not alter germline genetics.

Answer

The assertion relies on the inheritance of acquired characteristics, which is invalid because somatic modifications caused by environmental use do not alter germline genetics.
The correct answer highlights the fundamental flaw in Lamarckian evolution. Physical changes occurring in body cells (somatic tissue) due to use or environmental strain are not encoded in gametes (germline tissue), meaning they cannot be inherited by offspring.

Step-by-Step Solution

1
Analyze the researcher's claim
The claim states that physical stretching of webbed feet during an individual's lifetime (a somatic modification) is directly passed to offspring.
This proposal reflects Jean-Baptiste Lamarck's hypothesis of the inheritance of acquired characteristics.
2
Evaluate against modern evolutionary biology principles
Modern genetics establishes that evolutionary inheritance occurs via germline DNA in gametes, not somatic changes in body tissues resulting from use or disuse.
Somatic adaptations acquired during an organism's lifetime do not alter gametic genotype, rendering Lamarck's mechanism scientifically invalid.

Key Concept

Lamarck's Theory of Inheritance of Acquired Characteristics vs. Modern Genetics
Question 6Question →

Match each Lamarckian evolutionary postulate or related historical concept on the left with its corresponding descriptive statement or experimental critique on the right.

Click a left item, then click its matching right item

Items

Principle of Use and Disuse
Inheritance of Acquired Characteristics
Environmental Need (Besoin)
Germplasm Theory Critique

Matches

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Answer

Principle of Use and Disuse matches the statement regarding organ hypertrophy through exertion and atrophy through disuse. Inheritance of Acquired Characteristics matches the statement regarding somatic modifications being passed to progeny. Environmental Need (Besoin) matches the statement about environmental shifts creating new demands that drive behavioral and structural adaptations. Germplasm Theory Critique matches the experimental proof that somatic changes do not affect germ cells.
Each concept correctly aligns with its historical definition or scientific critique. The principle of use and disuse concerns organ development through exertion or atrophy through neglect. Inheritance of acquired characteristics describes the transfer of somatic traits to progeny. Environmental need explains how changing surroundings prompt adaptive responses. Germplasm theory refutes Lamarckism by demonstrating the separation of somatic and reproductive cells.

Step-by-Step Solution

1
Analyze the core postulates of Lamarckism and the primary historical counter-evidence.
Identify the definitions of use and disuse, acquired traits, environmental needs, and Weismann's germplasm theory.
Clear differentiation between Lamarck's mechanisms and their experimental refutation is necessary to pair each concept accurately.
2
Match 'Principle of Use and Disuse' to its mechanism.
Pairs with the description detailing organ enlargement from frequent use and degeneration from disuse.
Lamarck proposed that physical exertion directly alters organ structure within an individual's lifetime.
3
Match 'Inheritance of Acquired Characteristics' to its definition.
Pairs with the statement that lifespan modifications are transmitted to subsequent generations.
This postulate erroneously assumed somatic changes could be inherited.
4
Match 'Environmental Need (Besoin)' and 'Germplasm Theory Critique' to their remaining descriptions.
Environmental Need pairs with environmental shifts creating new demands, and Germplasm Theory Critique pairs with the distinction between somatic and germ cells.
Lamarck emphasized environmental stimulus for adaptation, while Weismann proved germ cells are isolated from somatic changes.

Key Concept

Lamarckian Evolutionary Principles and Germplasm Counter-Evidence
Question 7Question →

In Jean-Baptiste Lamarck's theory of evolution, a changing environment causes direct physical alterations to an organism's body without requiring changes in the organism's behavioral habits or organ usage.

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Answer: False

Answer

False
The statement is false because Lamarck specified that environmental change acts indirectly. A changing environment creates new needs, which compel changes in an organism's behavioral habits. These changed habits determine which organs undergo increased use or disuse, thereby altering their physical structure prior to inheritance.

Step-by-Step Solution

1
Analyze Lamarck's foundational sequence for evolutionary adaptation.
Lamarck postulated that changes in the environment alter an organism's needs (besoins), which in turn induce new habits and actions.
Establishing the sequence of cause-and-effect in Lamarckism is necessary to differentiate indirect environmental influence from direct physical induction.
2
Evaluate the mediating role of behavioral habits and organ use or disuse.
Anatomical modifications develop as a direct consequence of altered organ usage resulting from changed habits, rather than from passive environmental exposure.
Lamarck stressed that behavioral changes mediate between environmental demands and anatomical modifications.
3
Determine the validity of the statement.
The statement asserts direct structural modification without habit or usage changes, which contradicts Lamarck's explicit mechanism.
Because Lamarckian evolution relies strictly on behavioral habits and differential use/disuse as intermediate steps, the statement is false.

Key Concept

Lamarckian Evolutionary Sequence: Environmental Changes → Modified Needs → Changed Habits → Organ Use/Disuse → Acquired Structural Modifications
Estimated Time:1m 30s
Question 8Question →

Jean-Baptiste Lamarck proposed an early mechanism to explain evolutionary change. Which of the following statements correctly describes a fundamental principle of his theory?

Show answer & explanation

Answer: Physical traits acquired through the frequent use or disuse of body parts during an organism's lifetime are transmitted to its offspring.

Answer

Physical traits acquired through the frequent use or disuse of body parts during an organism's lifetime are transmitted to its offspring.
The correct answer accurately states Lamarck's central hypothesis: organisms adapt during their lifetime through the use or disuse of structures, and these acquired somatic changes are passed down to offspring.

Step-by-Step Solution

1
Identify the primary mechanism proposed by Jean-Baptiste Lamarck.
Lamarck postulated that environment-driven need causes organisms to use or disuse certain body parts, altering their physical structures.
This establishes the law of use and disuse.
2
Determine how Lamarck believed these physical alterations were passed to subsequent generations.
He claimed that these acquired somatic alterations are directly inherited by offspring.
This is known as the inheritance of acquired characteristics.

Key Concept

Lamarck's Theory of Evolution (Use and Disuse, Inheritance of Acquired Characteristics)
Question 9Question →

According to Jean-Baptiste Lamarck's theory of evolution, an organ subjected to continuous and increased functional demand during an organism's lifetime undergoes structural hypertrophy, and this acquired modification is directly transmitted to subsequent generations.

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Answer: True

Answer

True. Lamarck's evolutionary model explicitly combines organ development through functional use (hypertrophy) with the transgenerational inheritance of acquired physical characteristics.
The statement is true because Jean-Baptiste Lamarck's evolutionary mechanism fundamentally relies on two interconnected ideas: that increased functional demand causes organ development and hypertrophy within an organism's lifetime, and that these acquired somatic traits are preserved and passed to offspring.

Step-by-Step Solution

1
Examine Lamarck's first postulate concerning organ modification during an individual's lifetime.
Lamarck proposed that increased environmental need leads to increased organ usage, resulting in physical enlargement and enhanced development (hypertrophy) of the affected somatic structure.
This establishes the principle of use and disuse within an organism's lifespan.
2
Examine Lamarck's second postulate concerning transgenerational transmission.
Lamarck asserted that physical changes acquired by an individual through use or disuse during its lifetime are directly inherited by its progeny.
This links individual somatic adaptation to evolutionary changes across generations.
3
Evaluate the accuracy of the statement against Lamarckian theory.
The statement correctly combines both fundamental postulates of Lamarckism without introducing modern genetic concepts.
Confirms the statement as true.

Key Concept

Lamarck's Postulates of Use/Disuse and Inheritance of Acquired Traits
Question 10Question →

A botanist repeatedly prunes a species of shrub over its lifetime, causing it to develop a compact, stunted growth form. When seeds harvested from this pruned shrub are grown under normal, unpruned conditions, all offspring develop into full-sized plants of standard height. Which of the following conclusions best refutes Lamarck's theory of evolution based on this result?

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Answer: Acquired somatic modifications resulting from environmental manipulation are not transferred to gametes or inherited by offspring.

Answer

Acquired somatic modifications resulting from environmental manipulation are not transferred to gametes or inherited by offspring.
Lamarck's theory of evolution proposed that organisms pass on physical features acquired during their lifetime to their offspring (inheritance of acquired characteristics). The experiment demonstrates that pruning—an environmentally induced somatic change—does not alter the genetic code in the plant's reproductive cells (germline). Consequently, the offspring inherit the unedited genetic instructions for normal growth, refuting Lamarck's proposed mechanism.

Step-by-Step Solution

1
Identify the key postulate of Lamarck's Theory of Evolution being tested.
Lamarck's theory relies on the inheritance of acquired characteristics (somatic changes developed during an organism's life are passed to offspring).
Understanding Lamarck's mechanism is essential to evaluating why empirical evidence refutes it.
2
Analyze the experimental observations.
The parent plant acquired a stunted phenotype due to artificial pruning (environmental intervention), but its offspring produced from seed grew to normal height.
This shows that bodily changes (somatic cells) caused by environmental factors do not alter reproductive cells (germ cells).
3
Deduce the biological principle that invalidates the Lamarckian claim.
Phenotypic changes in somatic tissues are not encoded in DNA within germline cells, thereby proving acquired characteristics cannot be inherited.
Modern genetics and Weismann's germplasm concept confirm that only germline mutations/variations are transmitted across generations.

Key Concept

Inheritance of Acquired Characteristics vs. Somatic and Germline Differentiation
Estimated Time:1m 30s
Question 11Question →

A professional athlete undergoes years of intensive physical conditioning, resulting in significantly enlarged skeletal muscles and increased lung capacity. Based on the fundamental postulates of Lamarck's theory of evolution, which of the following outcomes would be predicted for this athlete's offspring?

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Answer: They would naturally inherit larger muscles and increased lung capacity at birth without needing to undergo physical conditioning.

Answer

The offspring would naturally inherit larger muscles and increased lung capacity at birth without needing physical conditioning.
The correct option accurately reflects Lamarck's postulate of the 'Inheritance of Acquired Characteristics.' Jean-Baptiste Lamarck proposed that structural modifications acquired by an organism through frequent organ use or environmental response during its lifetime are directly transmitted to its offspring.

Step-by-Step Solution

1
Identify the core principle of Lamarckism being tested in the scenario.
Lamarck's theory is built on two primary tenets: the Law of Use and Disuse, and the Law of Inheritance of Acquired Characteristics.
Understanding Lamarckian principles allows us to predict how acquired physical adaptations are thought to pass to offspring under his framework.
2
Apply the Law of Inheritance of Acquired Characteristics to the athlete's muscular development.
According to Lamarck, physical changes (enlarged muscles, increased lung capacity) gained by an individual during their lifetime through use are directly passed down to their offspring.
Lamarck believed that modifications in somatic organs directly influence the structural characteristics born into the next generation.

Key Concept

Inheritance of Acquired Characteristics
Question 12Question →

Match each core Lamarckian evolutionary postulate or related historical criticism on the left with its accurate biological mechanism or empirical evaluation on the right.

Click a left item, then click its matching right item

Items

Principle of Use and Disuse
Inheritance of Acquired Characteristics
Internal Vital Impulse
Weismann's Germplasm Barrier

Matches

Show answer & explanation

Answer

Principle of Use and Disuse pairs with organ hypertrophy or atrophy from functional demand; Inheritance of Acquired Characteristics pairs with direct transmission of somatic changes to offspring; Internal Vital Impulse pairs with the proposed innate drive for complexity from non-living matter; Weismann's Germplasm Barrier pairs with the experimental refutation showing somatic changes do not affect germ line genetics.
Each concept correctly aligns with its historical and biological definition: Use and Disuse describes organ changes within a lifespan; Inheritance of Acquired Characteristics describes the proposed transfer of those changes to offspring; Internal Vital Impulse accounts for the drive toward complexity; and Weismann's Germplasm Barrier provides the classical empirical refutation distinguishing germline inheritance from somatic changes.

Step-by-Step Solution

1
Analyze the primary tenets of Lamarckism
Identify Use and Disuse as somatic modification during life, Inheritance of Acquired Traits as intergenerational transfer of those modifications, and Vital Impulse as the inherent drive for complexity.
Lamarck's theory relies on these distinct physiological and evolutionary mechanisms.
2
Evaluate historical scientific critiques of Lamarckian mechanisms
Recognize Weismann's experiment as establishing the barrier between germline (hereditary) and soma (body) cells.
Modern genetics refutes Lamarckism because somatic adaptations do not alter gametic DNA.
3
Match each postulate and critique to its corresponding definition
Connect left item 1 to right item 3, left item 2 to right item 4, left item 3 to right item 1, and left item 4 to right item 2.
Ensures precise conceptual mapping based on evolutionary biological definitions.

Key Concept

Lamarckian Postulates and Historical Refutation
Question 13Question →

A population of burrowing rodents living in permanent underground darkness possesses small, vestigial eyes covered by skin. According to Jean-Baptiste Lamarck's mechanism of evolution, which of the following best explains how these animals lost their functional eyesight?

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Answer: Continuous disuse of the eyes in darkness led to their gradual reduction during an individual's lifetime, and this acquired trait was inherited by offspring.

Answer

Continuous disuse of the eyes in darkness led to their gradual reduction during an individual's lifetime, and this acquired trait was inherited by offspring.
Lamarck's theory of evolution is built on two primary principles: the law of use and disuse (organs used extensively develop, while those unused atrophy) and the inheritance of acquired characteristics (somatic modifications gained during an organism's life are passed to offspring). The explanation stating that continuous disuse in darkness reduced the eyes and this acquired modification was inherited accurately reflects Lamarck's hypothesis.

Step-by-Step Solution

1
Identify the primary postulates of Lamarck's theory of evolution.
Lamarck's theory relies on two main ideas: the law of use and disuse, and the inheritance of acquired characteristics.
Understanding the core mechanism proposed by Lamarck is required to evaluate the scenario.
2
Apply the law of disuse to the scenario of subterranean rodents.
Living in complete darkness means the eyes are not used, causing them to degenerate or atrophy over the animal's lifetime.
Lamarck stated that organs not subjected to regular functional demand progressively shrink and lose function.
3
Apply the law of inheritance of acquired traits.
The reduced state of the eyes acquired during the parent's lifetime is transmitted to its offspring.
According to Lamarck, somatic changes developed through use or disuse are directly inheritable.

Key Concept

Lamarck's Law of Use and Disuse and Inheritance of Acquired Characteristics
Question 14Question →

Ancestral reptiles are believed to have possessed fully developed limbs. According to Jean-Baptiste Lamarck's evolutionary principles, which process accounts for the complete loss of functional limbs in modern snakes?

Show answer & explanation

Answer: Continuous disuse of limbs during crawling in narrow spaces, followed by the inheritance of this acquired trait by offspring

Answer

Continuous disuse of limbs during crawling in narrow spaces, followed by the inheritance of this acquired trait by offspring.
Lamarck postulated that when an organism disuses a structure due to changing environmental habits (such as snakes crawling through tight crevices), that organ gradually atrophies and deteriorates. He maintained that such acquired somatic traits are directly inherited by offspring.

Step-by-Step Solution

1
Identify Lamarck's two core evolutionary postulates
Lamarck's theory relies on the Law of Use and Disuse and the Law of Inheritance of Acquired Characteristics.
Frequent use strengthens an organ while continuous disuse causes atrophy, and changes acquired during an organism's life are transmitted to offspring.
2
Apply these postulates to the evolution of limblessness in snakes
Crawling through narrow spaces led to the disuse and eventual reduction of limbs, and this limbless condition was inherited across generations.
Lamarck specifically cited snakes losing legs through disuse as a primary example of his evolutionary theory.

Key Concept

Lamarck's Theory of Use and Disuse and Inheritance of Acquired Characteristics
Estimated Time:1m 0s
Question 15Question →

Which of the following statements correctly summarizes Jean-Baptiste Lamarck's explanation for how structural adaptations arise and are preserved in a species over successive generations?

Show answer & explanation

Answer: Environmentally induced somatic modifications acquired by an individual through use or disuse are directly transmitted to its progeny.

Answer

Environmentally induced somatic modifications acquired by an individual through use or disuse are directly transmitted to its progeny.
Jean-Baptiste Lamarck hypothesized that changes acquired by an organism during its lifetime through the use or disuse of structures are inherited directly by its offspring, leading to evolutionary change over generations.

Step-by-Step Solution

1
Analyze Lamarck's core evolutionary principles.
Lamarck proposed two primary laws: the Law of Use and Disuse, and the Law of Inheritance of Acquired Characteristics.
Understanding Lamarckism requires identifying that acquired somatic changes were believed to be passed to subsequent generations.
2
Differentiate Lamarckian mechanisms from Darwinian natural selection and modern genetics.
Lamarckism claims environment directly causes phenotypic changes in somatic cells that are inherited, whereas natural selection acts on pre-existing genetic variation.
Distractors confuse Lamarckian acquired inheritance with Darwinian selection and genetic mutations.

Key Concept

Lamarck's Theory of Inheritance of Acquired Characteristics
Estimated Time:1m 0s
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