Evolution and Taxonomy Study Guide PDF

Evolution and Taxonomy ====================== - **Introduction to Evolution**: - Definition: The process by which species change over time through genetic variation and natural selection. - Evolution explains the diversity of life on Earth. - **Key Contributors**: -...

Evolution and Taxonomy ====================== - **Introduction to Evolution**: - Definition: The process by which species change over time through genetic variation and natural selection. - Evolution explains the diversity of life on Earth. - **Key Contributors**: - **Charles Darwin**: Proposed *natural selection* as the mechanism of evolution in *On the Origin of Species*. - **Alfred Russel Wallace**: Independently conceived the idea of natural selection. - **Jean-Baptiste Lamarck**: Suggested inheritance of acquired traits (e.g., giraffes\' necks elongating by stretching); later disproven but significant historically. - **Charles Lyell**: Advocated for *uniformitarianism*, the idea that geological processes we observe today also shaped the past, influencing Darwin's ideas. **Evidence for Evolution** - **Fossil Evidence**: - Shows changes in species over time. - Transitional fossils link ancient species to modern descendants (e.g., *Archaeopteryx* links birds and reptiles). - **Anatomical Evidence**: - Homologous structures: Similar structures in different species indicating common ancestry (e.g., human arm, bat wing, whale flipper). - Vestigial structures: Reduced or unused structures indicating evolutionary history (e.g., human tailbone). - **Biochemical Evidence**: - DNA and protein comparisons show similarities among species. - More closely related species have more similar genetic sequences. - **Biogeographical Evidence**: - Geographic distribution of species aligns with evolutionary theory. - Examples: Marsupials are mostly in Australia due to continental drift. - **Artificial Selection**: - Humans selecting traits in breeding (e.g., dog breeds, agricultural crops) mimics natural selection, showing how traits can evolve over time. **Natural Selection in Detail** - **Mechanisms of Natural Selection**: - Overproduction of offspring: More offspring are produced than can survive. - Variation: Individuals in a population vary in traits. - Adaptation: Traits that provide survival or reproductive advantages become more common. - Descent with modification: Over generations, populations evolve. - **Key Examples**: - Peppered moth during the Industrial Revolution. - Darwin's finches and their beak adaptations. **Taxonomy and Classification** - **What is Taxonomy?** - The science of naming, describing, and classifying organisms. - Hierarchical system developed by Carl Linnaeus: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. - **Importance of Taxonomy**: - Helps organize biological diversity. - Aids in understanding evolutionary relationships. - **Modern Taxonomy**: - Uses phylogenetics (evolutionary trees) and molecular data (DNA sequencing) to classify species. - Groups organisms based on shared ancestry. Ecosystems ========== **Definition** - An ecosystem is a community of living organisms (biotic factors) interacting with their non-living environment (abiotic factors). - Examples: Forests, deserts, wetlands. **Components of Ecosystems**: - Biotic: Plants, animals, microbes. - Abiotic: Climate, soil, water, sunlight. - Energy flow: From producers (plants) to consumers (animals) and decomposers. - Nutrient cycling: Carbon, nitrogen, and water cycles sustain life. **Why Ecosystems Vary by Location**: 1. **Earth's Rotation**: - Causes day and night, influencing temperature and photosynthesis. - Drives global wind patterns affecting climate. 2. **Earth's Axis Tilt**: - Seasons occur because the Earth's axis is tilted (23.5°). - Regions near the equator receive constant sunlight, while poles have extreme seasonal variation. 3. **Latitude**: - Determines climate zones: - **Tropics** (near equator): Warm, wet, high biodiversity (e.g., rainforests). - **Temperate zones**: Moderate climates (e.g., grasslands, deciduous forests). - **Polar zones**: Cold, dry (e.g., tundra). 4. **Proximity to the Sea**: - Oceans moderate coastal climates, keeping temperatures more stable. - Inland areas experience greater extremes. 5. **Ocean Currents**: - Move warm or cold water across the globe, influencing coastal climates. - Example: The Gulf Stream warms Western Europe. 6. **Altitude**: - Higher altitudes have cooler temperatures and lower oxygen levels. - Example: Alpine ecosystems are similar to tundra due to low temperatures. 7. **Wind Patterns**: - Trade winds, westerlies, and polar easterlies distribute heat and moisture. - Monsoons and hurricanes are driven by these patterns. 8. **Rainshadow Effect**: - Mountains block moist air, causing one side to receive rain (windward) and the other to be dry (leeward). - Example: Deserts on the leeward side of the Andes. **Major Ecosystems (Biomes)** 1. **Tropical Rainforests**: - Hot, wet, high biodiversity (e.g., Amazon). 2. **Savannas**: - Warm, seasonal rainfall, grasses dominate. 3. **Deserts**: - Dry, extreme temperatures, sparse vegetation (e.g., Sahara). 4. **Grasslands**: - Moderate rainfall, dominated by grasses (e.g., North American prairies). 5. **Temperate Deciduous Forests**: - Seasonal changes, diverse plant and animal life. 6. **Taiga (Boreal Forest)**: - Cold, coniferous forests, long winters. 7. **Tundra**: - Cold, treeless, permafrost soil. 8. **Aquatic Ecosystems**: - Freshwater (lakes, rivers) and marine (oceans, coral reefs). Energy flow: Photosynthesis and Cellular respiration ==================================================== **Photosynthesis** - **Definition**: - The process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. - **Where it Happens**: - **Chloroplasts** in plant cells, specifically in the **thylakoid membranes** and the **stroma**. - Key molecule: **Chlorophyll** absorbs sunlight. - **Stages of Photosynthesis**: - **Light-Dependent Reactions**: - Location: Thylakoid membranes. - Inputs: Sunlight and water (H₂O). - Outputs: Oxygen (O₂, released), ATP, and NADPH. - Process: Light splits water molecules (photolysis), releasing O₂ and transferring energy to ATP and NADPH. - **Light-Independent Reactions (Calvin Cycle)**: - Location: Stroma of the chloroplast. - Inputs: ATP, NADPH, and carbon dioxide (CO₂). - Outputs: Glucose (C₆H₁₂O₆). - Process: CO₂ is fixed into glucose through a series of enzyme-driven steps. **Cellular Respiration** - **Definition**: - The process by which all living cells break down glucose to release energy stored as ATP (adenosine triphosphate). - **Where it Happens**: - **Cytoplasm** (for glycolysis). - **Mitochondria** (for the Krebs cycle and electron transport chain). - **Stages of Cellular Respiration**: - **Glycolysis**: - Location: Cytoplasm. - Inputs: Glucose (C₆H₁₂O₆) and 2 ATP. - Outputs: 2 pyruvate molecules, 2 NADH, and 4 ATP (net gain: 2 ATP). - **Krebs Cycle (Citric Acid Cycle)**: - Location: Mitochondrial matrix. - Inputs: Pyruvate (converted to Acetyl-CoA), NAD⁺, and FAD. - Outputs: Carbon dioxide (CO₂, released), NADH, FADH₂, and 2 ATP. - **Electron Transport Chain (ETC)**: - Location: Inner mitochondrial membrane. - Inputs: NADH, FADH₂, and oxygen (O₂). - Outputs: Water (H₂O) and about 32-34 ATP. - Process: Electrons from NADH and FADH₂ are passed through protein complexes, driving ATP production via oxidative phosphorylation. **omparing Photosynthesis and Cellular Respiration** - **Key Differences**: - **Photosynthesis**: - Location: Chloroplasts. - Purpose: Converts light energy into glucose. - Reactants: CO₂, H₂O, sunlight. - Products: Glucose (C₆H₁₂O₆) and O₂. - **Cellular Respiration**: - Location: Mitochondria. - Purpose: Breaks down glucose to release energy as ATP. - Reactants: Glucose (C₆H₁₂O₆) and O₂. - Products: CO₂, H₂O, and ATP. - **Energy Flow**: - Photosynthesis stores energy; respiration releases it. - The two processes form a cycle, with oxygen and glucose produced by photosynthesis used in respiration, and CO₂ and water from respiration used in photosynthesis. The equations for photosynthesis and cellular respiration are the opposite of each other, as the products of one process are the reactants of the other: - **Photosynthesis**: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2 - **Cellular respiration**: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (in ATP) Biotic relations ================ **Definition**: - Biotic relationships are interactions between living organisms in an ecosystem. - These relationships affect population size, survival, and the structure of communities. **Tyes of Interactions**: - Intraspecific: Between members of the same species. - Interspecific: Between members of different species. **Types of Biotic Relationships** 1. **Mutualism** (*+ +*): - Both species benefit. - Example: Bees pollinate flowers while getting nectar as food. - Importance: Drives coevolution and increases biodiversity. 2. **Commensalism** (*+ 0*): - One species benefits, the other is unaffected. - Example: Barnacles attach to whales for transport, while whales remain unaffected. 3. **Parasitism** (*+ -*): - One species benefits at the expense of the other. - Example: Ticks feed on the blood of mammals, harming the host. - Includes endoparasites (inside host, e.g., tapeworms) and ectoparasites (on host's surface, e.g., lice). 4. **Competition** (*- -*): - Both species are harmed as they vie for the same limited resources. - Types: - **Intraspecific Competition**: Within the same species (e.g., deer competing for mates). - **Interspecific Competition**: Between different species (e.g., lions and hyenas competing for prey). - May lead to resource partitioning or competitive exclusion. 5. **Predation** (*+ -*): - One organism (predator) hunts and kills another (prey) for food. - Example: Lions hunting zebras. - Importance: Regulates population sizes and promotes natural selection. 6. **Herbivory** (*+ -*): - An animal feeds on plants. - Example: Caterpillars eating leaves. - Plants may evolve defenses like toxins or thorns. 7. **Amensalism** (*- 0*): - One species is harmed while the other is unaffected. - Example: Large trees shading smaller plants, reducing their growth. **Special Biotic Relationships** - **Keystone Species**: - A species with a disproportionately large impact on its ecosystem. - Example: Sea otters control sea urchin populations, protecting kelp forests. - **Symbiosis**: - Close, long-term interactions between species. - Includes mutualism, commensalism, and parasitism. - **Facilitation**: - Indirect positive effect of one species on another. - Example: Pioneer plants improving soil quality for later species in succession. **Importance of Biotic Relationships** - **Maintaining Ecosystem Balance**: - Relationships regulate population sizes and resource availability. - **Driving Evolution**: - Interactions, such as predator-prey dynamics or mutualism, promote adaptations. - **Biodiversity**: - Complex relationships increase species richness and ecosystem resilience.