Biology notes
Main Takeaway
Biology is the scienti c study of life, focusing on understanding the diverse characteristics of living
organisms, their interactions, and the fundamental processes that unite all life forms.
1.1 The Characteristics of Life
Basic Characteristics of Life
Levels of Organization
Begins with atoms
Progresses through molecules, cells, tissues, organs, organ systems
Extends to populations, species, communities, ecosystems, and biosphere
Material and Energy Requirements
All life needs external sources of materials and energy
Metabolism: All chemical reactions occurring in a cell
Producers (e.g., plants) transform solar energy into chemical energy
Energy ows through ecosystems, gradually dissipating as heat
Homeostasis
Maintaining internal stability (temperature, moisture, acidity)
Organisms have mechanisms to regulate internal environment
Examples: Lizards basking in sun, liver releasing stored sugar
Response to Stimuli
Organisms interact with surroundings
Responses can range from simple (bacterial movement) to complex (animal migration)
Helps ensure survival
Reproduction and Development
All living organisms can reproduce
Involves passing genetic information (DNA)
Reproduction can be:
Simple (single-cell division)
Complex (sexual reproduction with genetic inheritance)
Adaptations
Modi cations that suit organisms to their environment
Examples:
Hawks' specialized hunting abilities
Human adaptations to high-altitude environments
1.2 Evolution: The Core Concept of Biology
Key Points
De nition: Process of populations changing over time to adapt to environments
Unifying Concept of Biology
Explains life's diversity
Describes adaptations
Traces life's origins
Natural Selection
Proposed by Charles Darwin and Alfred Russell Wallace
Mechanism of evolutionary change
Involves:
Environmental changes
Di erential reproductive success
Adaptation of traits that enhance survival
Importance of Diversity in Science
, Diverse scienti c community brings:
Unique perspectives
Broader range of questions
More comprehensive problem-solving
Critical for addressing global challenges like climate change and emerging diseases
Concluding Thoughts
Life is incredibly diverse
All living organisms share fundamental characteristics
Understanding these characteristics helps us comprehend the complexity of life
Common Descent with Modi cation
• Organisms descend from common ancestors and develop speci c adaptations
• Adaptations allow species to play particular roles in their environment
Hawaiian Honeycreepers: A Case Study
• Over 50 known species (only 17 remain today)
• Evolved from a single species originating in North America
• Developed diverse bill shapes for di erent feeding habits
• Retain common characteristics from original ancestor
Evolution and Natural Selection
Practical Applications
• Helps understand diversity of life
• Provides insights into disease prevention and treatment
Antibiotic Resistance Example
• Bacteria can develop resistance through various mechanisms
• Widespread antibiotic use favors evolution of resistant strains
COVID-19 and Viral Evolution
• SARS-CoV-2 demonstrates rapid mutation capabilities
• Creates new variants that challenge immune systems
Biological Classi cation
Taxonomy and Systematics
• Taxonomy: Identifying and naming organisms
• Systematics: Classifying organisms by evolutionary relationships
Classi cation Categories (Least to Most Inclusive)
1. Species
2. Genus
3. Family
4. Order
5. Class
6. Phylum
7. Kingdom
8. Supergroup
9. Domain
Three Domains of Life
1. Bacteria
• Prokaryotic
• Found almost everywhere
• Some cause diseases, others provide useful services
2. Archaea
• Prokaryotic
• Live in extreme environments
• Potentially representative of rst cellular life
• fi
•
Main Takeaway
Biology is the scienti c study of life, focusing on understanding the diverse characteristics of living
organisms, their interactions, and the fundamental processes that unite all life forms.
1.1 The Characteristics of Life
Basic Characteristics of Life
Levels of Organization
Begins with atoms
Progresses through molecules, cells, tissues, organs, organ systems
Extends to populations, species, communities, ecosystems, and biosphere
Material and Energy Requirements
All life needs external sources of materials and energy
Metabolism: All chemical reactions occurring in a cell
Producers (e.g., plants) transform solar energy into chemical energy
Energy ows through ecosystems, gradually dissipating as heat
Homeostasis
Maintaining internal stability (temperature, moisture, acidity)
Organisms have mechanisms to regulate internal environment
Examples: Lizards basking in sun, liver releasing stored sugar
Response to Stimuli
Organisms interact with surroundings
Responses can range from simple (bacterial movement) to complex (animal migration)
Helps ensure survival
Reproduction and Development
All living organisms can reproduce
Involves passing genetic information (DNA)
Reproduction can be:
Simple (single-cell division)
Complex (sexual reproduction with genetic inheritance)
Adaptations
Modi cations that suit organisms to their environment
Examples:
Hawks' specialized hunting abilities
Human adaptations to high-altitude environments
1.2 Evolution: The Core Concept of Biology
Key Points
De nition: Process of populations changing over time to adapt to environments
Unifying Concept of Biology
Explains life's diversity
Describes adaptations
Traces life's origins
Natural Selection
Proposed by Charles Darwin and Alfred Russell Wallace
Mechanism of evolutionary change
Involves:
Environmental changes
Di erential reproductive success
Adaptation of traits that enhance survival
Importance of Diversity in Science
, Diverse scienti c community brings:
Unique perspectives
Broader range of questions
More comprehensive problem-solving
Critical for addressing global challenges like climate change and emerging diseases
Concluding Thoughts
Life is incredibly diverse
All living organisms share fundamental characteristics
Understanding these characteristics helps us comprehend the complexity of life
Common Descent with Modi cation
• Organisms descend from common ancestors and develop speci c adaptations
• Adaptations allow species to play particular roles in their environment
Hawaiian Honeycreepers: A Case Study
• Over 50 known species (only 17 remain today)
• Evolved from a single species originating in North America
• Developed diverse bill shapes for di erent feeding habits
• Retain common characteristics from original ancestor
Evolution and Natural Selection
Practical Applications
• Helps understand diversity of life
• Provides insights into disease prevention and treatment
Antibiotic Resistance Example
• Bacteria can develop resistance through various mechanisms
• Widespread antibiotic use favors evolution of resistant strains
COVID-19 and Viral Evolution
• SARS-CoV-2 demonstrates rapid mutation capabilities
• Creates new variants that challenge immune systems
Biological Classi cation
Taxonomy and Systematics
• Taxonomy: Identifying and naming organisms
• Systematics: Classifying organisms by evolutionary relationships
Classi cation Categories (Least to Most Inclusive)
1. Species
2. Genus
3. Family
4. Order
5. Class
6. Phylum
7. Kingdom
8. Supergroup
9. Domain
Three Domains of Life
1. Bacteria
• Prokaryotic
• Found almost everywhere
• Some cause diseases, others provide useful services
2. Archaea
• Prokaryotic
• Live in extreme environments
• Potentially representative of rst cellular life
• fi
•
