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Attached are the class notes of 10th std Biology Textbook Ch 2 Paths of Evolution.
Introduction to Evolution
Evolution is the process through which complex multicellular organisms have developed from simple unicellular ancestors, leading to the biodiversity observed today. This chapter explores the
mechanisms of evolution, theories like Lamarckism and Darwinism, evidence supporting evolution, and the role of the nervous system in evolutionary adaptations.
Theories of Evolution
Lamarckism (Theory of Inheritance of Acquired Characters)
• Proposed by: Jean Baptiste Lamarck, a French biologist.
• Core Idea: Organisms acquire characteristics during their lifetime due to environmental
changes, and these acquired traits are passed to offspring.
• Example (Giraffes):
o Short-necked giraffes stretched their necks to reach higher leaves due to food scarcity.
o This elongation was passed to subsequent generations, resulting in long-necked giraffes.
• Illustration 2.1 Analysis:
o Change in Environment: Scarcity of ground-level food forced giraffes to reach higher branches.
o Acquired Character: Neck elongation due to stretching.
o Inheritance: Acquired longer necks passed to offspring.
o Survival: Giraffes with longer necks survived better in the changed environment.
• Criticism: Later studies showed acquired traits do not alter genetic structure and are not inherited.
Darwinism (Theory of Natural Selection)
• Proposed by: Charles Darwin, an English naturalist.
• Core Idea: Organisms with favorable variations survive and reproduce, passing these traits to offspring, leading to new species over time.
• Key Concepts:
o Overproduction: Organisms produce more offspring than the environment can support.
o Variations: Individuals show differences in traits (e.g., size, immunity).
o Struggle for Existence: Competition for limited resources (food, shelter, mates).
o Survival of the Fittest: Organisms with favorable variations survive and reproduce.
o Natural Selection: Favorable traits accumulate, leading to new species.
For detailed notes on Kerala 10th std Biology Textbook Ch 2 Paths of Evolution Notes click below
Kerala 10th std Biology Textbook Ch 2 Paths of Evolution Notes.pdf (Size: 360.48 KB / Downloads: 1)
Introduction to Evolution
Evolution is the process through which complex multicellular organisms have developed from simple unicellular ancestors, leading to the biodiversity observed today. This chapter explores the
mechanisms of evolution, theories like Lamarckism and Darwinism, evidence supporting evolution, and the role of the nervous system in evolutionary adaptations.
Theories of Evolution
Lamarckism (Theory of Inheritance of Acquired Characters)
• Proposed by: Jean Baptiste Lamarck, a French biologist.
• Core Idea: Organisms acquire characteristics during their lifetime due to environmental
changes, and these acquired traits are passed to offspring.
• Example (Giraffes):
o Short-necked giraffes stretched their necks to reach higher leaves due to food scarcity.
o This elongation was passed to subsequent generations, resulting in long-necked giraffes.
• Illustration 2.1 Analysis:
o Change in Environment: Scarcity of ground-level food forced giraffes to reach higher branches.
o Acquired Character: Neck elongation due to stretching.
o Inheritance: Acquired longer necks passed to offspring.
o Survival: Giraffes with longer necks survived better in the changed environment.
• Criticism: Later studies showed acquired traits do not alter genetic structure and are not inherited.
Darwinism (Theory of Natural Selection)
• Proposed by: Charles Darwin, an English naturalist.
• Core Idea: Organisms with favorable variations survive and reproduce, passing these traits to offspring, leading to new species over time.
• Key Concepts:
o Overproduction: Organisms produce more offspring than the environment can support.
o Variations: Individuals show differences in traits (e.g., size, immunity).
o Struggle for Existence: Competition for limited resources (food, shelter, mates).
o Survival of the Fittest: Organisms with favorable variations survive and reproduce.
o Natural Selection: Favorable traits accumulate, leading to new species.
For detailed notes on Kerala 10th std Biology Textbook Ch 2 Paths of Evolution Notes click below
Kerala 10th std Biology Textbook Ch 2 Paths of Evolution Notes.pdf (Size: 360.48 KB / Downloads: 1)