Science Review - Intro to Chemistry PDF

INTRO TO CHEMISTRY Matter and Energy ​ Matter: Anything that takes up space and has weight (like your desk, water, or air). ​ Energy: The ability to do work or cause change (like light, heat, or motion). Properties of Matter ​ Physical Properties: Things you can observe without changing w...

INTRO TO CHEMISTRY Matter and Energy ​ Matter: Anything that takes up space and has weight (like your desk, water, or air). ​ Energy: The ability to do work or cause change (like light, heat, or motion). Properties of Matter ​ Physical Properties: Things you can observe without changing what it is (like color, shape, or boiling point). ​ Chemical Properties: How something reacts to form something new (like wood burning or metal rusting). Kinds of Matter 1.​ Elements: Pure substances made of only one kind of atom (like oxygen or gold). 2.​ Compounds: Substances made of two or more elements chemically combined (like water, H₂O). 3.​ Mixtures: Two or more substances mixed together but not chemically combined (like a salad or trail mix). Physical Changes ​ Changes in how something looks but not what it is (like cutting paper or melting ice). Chemical Changes ​ Changes that make something new (like baking a cake or iron rusting). Energy ​ It comes in different forms, like heat, light, and electricity, and it’s needed for all physical and chemical changes. Atoms ​ What are Atoms? The tiny building blocks of all matter. Everything is made of atoms! ​ Atom Facts: ○​ Atoms are super small. ○​ Made of three parts: protons (+), neutrons (neutral), and electrons (-). ​ Atoms and Elements: Atoms of the same type make up an element. For example, all gold atoms are the same. Compound vs. Element ​ Element: Made of one kind of atom (like oxygen). ​ Compound: Made of two or more elements chemically combined (like salt, NaCl). Properties of Compounds ​ Compounds often behave differently than the elements they’re made of. ○​ Example: Table salt (NaCl) is safe to eat, but its elements (sodium and chlorine) are dangerous by themselves! Properties of Compounds are different than the elements that make them Chemical Formula ​ A shorthand way to show what a compound is made of. ○​ Example: Water's formula is H₂O, meaning 2 hydrogen atoms and 1 oxygen atom are in every water molecule. Chemical Bonds ​ Chemical bonds hold atoms together to make compounds. ○​ Ionic bonds: Atoms give or take electrons (like salt). ○​ Covalent bonds: Atoms share electrons (like water). Mixture ​ A mix of two or more substances that aren’t chemically combined. ○​ Example: Sand and salt can be separated, so they’re a mixture. Periodic Table ​ A chart that organizes all known elements. ○​ Groups: The vertical columns; elements in the same group act similarly (like Group 1 are reactive metals). ○​ Periods: The horizontal rows; they show how many energy levels the atoms have. Where Everything Is on the Periodic Table 1.​ Metals: On the left and middle. They’re shiny, conduct electricity, and are bendy. 2.​ Non-Metals: On the right. They’re dull, brittle, and don’t conduct electricity. 3.​ Metalloids: In between metals and nonmetals. They have properties of both (like silicon). Trends in Ions on the Periodic Table ​ Ions are atoms that gain or lose electrons to get a charge. ○​ Metals usually lose electrons and become positive ions. ○​ Non-metals usually gain electrons and become negative ions. ​ As you go across the table, elements on the left (metals) are more likely to lose electrons, while those on the right (non-metals) are more likely to gain them. Ions are formed when atoms gain or lose electrons Gaining electrons = negative charge Losing electrons= positive charge Reactive Metals Group 1 – alkali metals -very reactive Group 2 - alkaline Earth Metals – reactive Transition metals Groups 3-12 – do not react as easily Many uses – modern technology, industry, car engines Form Alloys – two or more metals combined Rare Earth Elements Two rows that are outside periodic table Once thought to be available in short supply Not so rare, but hard to isolate Uses are becoming more abundant Classification of Non-Metals ​ Non-metals are elements that:  ○​ Don’t conduct heat or electricity well. ○​ Are brittle (they break easily). ○​ Are usually gases (like oxygen) or dull solids (like sulfur). ​ Examples: Oxygen (O), Carbon (C), and Nitrogen (N). Structure of Atoms ​ Atoms are tiny building blocks of everything. ​ Made up of three parts: 1.​ Protons: Positively charged particles found in the nucleus (center). 2.​ Neutrons: Neutral particles (no charge) also in the nucleus. 3.​ Electrons: Negatively charged particles that move around the nucleus in energy levels. What Protons, Neutrons, and Electrons Mean ​ Protons: The number of protons determines what element it is (e.g., 1 proton = hydrogen, 2 protons = helium).+ ​ Neutrons: Help hold the nucleus together. If there are more or fewer neutrons, it creates an isotope. ​ Electrons: Involved in chemical reactions. If atoms gain or lose electrons, they become ions.- Isotopes ​ Isotopes are atoms of the same element with different numbers of neutrons. ○​ Example: Carbon-12 and Carbon-14 are isotopes of carbon. Both have 6 protons, but Carbon-12 has 6 neutrons, and Carbon-14 has 8. Ions ​ Ions are atoms that have gained or lost electrons, giving them a charge: ○​ Positive Ions: Lose electrons (e.g., Na⁺). ○​ Negative Ions: Gain electrons (e.g., Cl⁻). What Isotopes and Ions Mean Together ​ Isotopes change the weight of the atom (due to neutrons). ​ Ions change the charge of the atom (due to electrons). ​ Example: A chlorine atom can have different isotopes (like Chlorine-35 or Chlorine-37) and also become an ion (like Cl⁻) if it gains an electron. Protons>Electrons = positive ion Protons10²⁷°C, and a "soup" of particles like quarks and electrons formed. ​ 3 minutes later: Universe cooled to 1 billion °C; atomic nuclei began forming. ​ 370,000-380,000 years later: Universe cooled to 10,000°C; first atoms (mainly hydrogen and helium) formed. ​ 300 million - 1 billion years later: Gas clouds formed stars and galaxies; temperature ~ -200°C. ​ 10 billion years later: First stars died, creating heavy elements used to form planets and celestial bodies. Evidence Supporting the Big Bang: ​ Redshift of Light: Observed through the Doppler Effect, galaxies moving away from Earth indicate the universe's expansion. ​ Cosmic Background Radiation: Low-energy radiation, an "afterglow" of the Big Bang, detected throughout the universe. ​ Star Composition: Stars are primarily hydrogen and helium, matching predictions of the first elements formed. Spectroscopy: ​ A technique used to analyze light emitted by substances, helping scientists determine the composition of stars and providing further evidence for the Big Bang. ​ Origin of the Solar System:  ○​ Nebular Hypothesis: About 4.6 billion years ago, a rotating gas and dust cloud formed the solar system. The Sun emerged from hydrogen fusion, and planetesimals combined to form planets, including Earth. ​ Milankovitch Cycles: ○​ Periodic changes in Earth's orbit, tilt, and wobble affect climate, leading to cycles of ice ages and interglacial periods. ○​ Tilt (41,000 years): Varies between 21.5°-24.5°; more tilt causes severe seasons, while less tilt moderates them. ○​ Eccentricity (100,000 years): Changes in Earth's orbit shape affect solar distance and seasons. ○​ Wobble (21,000 years): Alters timing of seasons. ​ Ice Ages: ○​ Occur roughly every 100,000 years due to various factors: Milankovitch cycles, atmospheric composition, solar output, volcanic activity, and asteroid impacts. ​ Reconstructing Earth's Past: ○​ Evidence includes mountain formation (Appalachians, Urals), fossil records (showing past climates and tectonic activity), and magnetic and geological data. ○​ Plate tectonics reshaped continents over time; Pangaea existed ~250 million years ago and broke into current continents. ​ Fossils: ○​ Preserve evidence of past life and inform the geologic time scale. ○​ Types include: ​ Original remains: Frozen (e.g., mammoths) or in amber. ​ Replaced remains: Minerals replace tissues (e.g., petrified wood). ​ Molds and casts: Impressions or mineral-filled replicas of organisms. ​ Trace fossils: Evidence of animal activity (e.g., footprints, burrows). ​ Carbonaceous films: Thin carbon silhouettes left after decomposition under pressure. The document outlines the geologic time scale, summarizing Earth's history as preserved in the rock record. It highlights the division of time into eons, eras, periods, and epochs, noting key developments: 1.​ Precambrian Time: Covers nearly 4 billion years with limited fossils, focusing on early life like cyanobacteria. 2.​ Paleozoic Era: Features a rich fossil record, including the Cambrian explosion and the rise of marine and terrestrial life. 3.​ Mesozoic Era: Known as the "Age of Dinosaurs," with periods like Triassic, Jurassic, and Cretaceous marked by evolutionary milestones and continental shifts. 4.​ Cenozoic Era: Starting 65 million years ago, it emphasizes the rise of mammals, modern plants, and human development. Relative Dating: ​ Principle of Superposition: In undisturbed sedimentary layers, the oldest rocks are at the bottom. ​ Principle of Cross-Cutting Relationships: Intrusions or cuts in rock layers are always younger than the layers they affect. ​ Unconformities: Gaps in the rock record caused by erosion or lack of sediment deposition, including angular unconformity, disconformity, and nonconformity. ​ Correlation: Matching rock layers across regions using characteristics, index fossils, and key beds. Index Fossils: ​ Unique, widespread, abundant, and from a short time period. ​ Serve as important tools for dating and environmental indicators. Absolute Dating: ​ Historical Methods: Estimating rates of erosion, tree-ring analysis, and varves (annual sediment layers). ​ Radioactivity: Using isotopes and radioactive decay to measure absolute time. ​ Radiometric Dating: Calculating the age of rocks by measuring parent and daughter isotopes, utilizing methods like Carbon-14, Uranium-lead, and Potassium-argon. WIND AND OCEAN CURRENTS Global Wind Patterns: 1.​ Air Pressure and Wind: ○​ Air moves from high to low pressure areas, influenced by the pressure gradient. ○​ Factors include temperature differences, Earth's rotation, friction, and local topography. 2.​ Coriolis Effect: ○​ Caused by Earth's rotation; deflects moving air to the right in the Northern Hemisphere and left in the Southern Hemisphere. ○​ Leads to spiral wind patterns around pressure systems. 3.​ Three-Cell Circulation Model: ○​ Describes atmospheric circulation in three cells per hemisphere (Polar, Ferrel, and Hadley cells). ○​ Explains general patterns of surface winds (e.g., Easterlies, Westerlies, Trade Winds). 4.​ Polar Front: ○​ At 60° latitude, cold polar air meets warmer mid-latitude air, creating rising air and low pressure. 5.​ Strengths and Weaknesses: ○​ Effective for large-scale wind and pressure patterns but oversimplifies effects of continents and seasons. Local Wind Patterns: 1.​ Sea and Land Breezes: ○​ Day: Sea breeze occurs as cool air moves from ocean (high pressure) to land (low pressure). ○​ Night: Land breeze forms as cool air moves from land (high pressure) to ocean (low pressure). 2.​ Mountain and Valley Breezes: ○​ Day: Warm air rises from the valley (valley breeze). ○​ Night: Cool air sinks into the valley (mountain breeze). 3.​ Monsoons: ○​ Seasonal wind shifts caused by pressure differences between continents and oceans, bringing dry winters and rainy summers. Key Takeaway: Wind patterns result from interactions between air pressure, temperature, Earth's rotation, and topography, influencing both global systems and localized phenomena. Surface currents Overview: ​ Surface Currents: Horizontal movement of seawater within the upper 1,000 meters of the ocean. ​ Driven by wind, the Coriolis effect, temperature differences, salinity, and friction. Patterns: ​ Northern Hemisphere: Currents flow clockwise. ​ Southern Hemisphere: Currents flow counterclockwise. ​ Equator: Warm currents flow away from the equator, and cold currents flow toward it. ​ Western ocean basins have warm, poleward currents, while eastern basins have cool, equatorward currents. Influences of Winds: ​ Trade Winds: Push equatorial currents westward. ​ Westerlies: Redirect currents eastward at higher latitudes. ​ Seasonal monsoons can alter wind and current directions. Examples of Currents: ​ Warm Currents: Gulf Stream (North Atlantic), Kuroshio Current (North Pacific). ○​ Bring warmth to regions like Iceland and the British Isles. ​ Cold Currents: Canary Current (North Atlantic), California Current (North Pacific), Benguela Current (South Atlantic). ○​ Labrador Current carries icebergs southward; East Greenland Current flows through the Strait of Denmark. Key Takeaway: Surface currents play a critical role in distributing heat, influencing global climates, and connecting ocean basins. Their direction and temperature are shaped by wind systems and Earth's rotation. Overview: ​ Deep Ocean Currents: ○​ Driven by gravity and density differences. ○​ Circulate for 500–2,000 years before recirculating. ○​ Connect with surface currents to form a global heat transport system. Causes of Density Currents: 1.​ Polar Regions: ○​ Cooling and freezing increase water density. ○​ Salt left behind during freezing raises salinity and density. ○​ Results in dense water masses: ​ Antarctic Bottom Water: Coldest and densest. ​ North Atlantic Deep Water: Second densest. ​ Antarctic Intermediate Water: Least dense among deep currents. 2.​ Evaporation: ○​ Warm, dry climates lead to high evaporation, increasing salinity and density. ○​ Example: Mediterranean Sea. Upwelling: ​ Vertical Currents: ○​ Cold, nutrient-rich deep water rises to the surface. ○​ Most common along western continental coasts (e.g., California, Peru). ○​ Supports phytoplankton growth and major fisheries. Key Takeaway: Deep ocean currents regulate global heat, oxygenate the deep sea, and support marine ecosystems, with upwelling zones being critical for nutrient cycling and biodiversity. WEATHERING AND EROSION Soil Overview: ​ Definition: Loose, weathered rock and organic material. ​ Parent Material: The underlying material from which soil forms, classified as: ○​ Residual Soil: Derived from bedrock beneath it (e.g., Bluegrass region, Kentucky). ○​ Transported Soil: Deposits moved by wind, rivers, or glaciers (e.g., New England). Soil Formation: ​ Formed by weathering of parent material, influenced by rock type and climate. ​ Organic matter (decayed plants and animals) mixes with bedrock material over time. Soil Profile: ​ Cross-section of soil layers (horizons): 1.​ A Horizon (Topsoil): Rich in humus. 2.​ B Horizon (Subsoil): Contains clay, minerals, and iron oxides, giving it a red color. 3.​ C Horizon: Slightly weathered parent material with rock fragments. Soil Composition: ​ Composed of sand, silt, and clay. ​ The proportions affect water retention and aeration (e.g., sandy soil drains quickly). Factors Influencing Soil: 1.​ Parent Material: Determines soil composition. 2.​ Plants and Animals: Contribute organic matter. 3.​ Topography: Affects water and organic content. 4.​ Climate: Plays a crucial role; soils in wet tropical climates are similar regardless of parent material. Key Takeaway: Soil formation is a dynamic process driven by weathering, organic contributions, and environmental factors, resulting in diverse soil profiles and compositions. Mass Movements: ​ Definition: Downward transportation of weathered materials due to gravity, exposing fresh rock for weathering. ​ Common at steep slopes, often resulting in talus (rock fragments at cliff bases). Types of Mass Movements: 1.​ Landslides: Rapid movement of rock/soil down slopes, common after heavy rains, snowmelt, or in volcanic/earthquake-prone areas. 2.​ Creep: Slow soil movement, causing objects like fences to tilt; water presence increases likelihood. 3.​ Slump: Blocks of land tilt and slide along a curved surface due to unsupported steep slopes.  4.​ Earthflows: Water-saturated soil flows downhill; velocity depends on water content, soil type, and slope steepness. 5.​ Mudflows: Rapid water-saturated flows of clay/silt, carrying debris at speeds up to 100 km/h; common in dry regions after heavy rains. Erosion: ​ Definition: Removal and transport of materials by natural agents like wind, water, glaciers, and waves. ​ Shapes landscapes, with outcomes influenced by climate and rock composition. ​ Humid Climates: Water erosion leads to rounded landscapes. ​ Dry Climates: Erosion creates sharp, jagged topography. ​ Resistant rocks erode slower, contributing to varied terrain. Key Takeaway: Mass movements and erosion continually reshape Earth's surface, influenced by gravity, water, climate, and rock characteristics, creating diverse landscapes over time. Weathering Overview: ​ Definition: Breakdown of rocks due to processes occurring at Earth's surface. ​ Types: 1.​ Mechanical Weathering: Physical breakdown without changing composition. 2.​ Chemical Weathering: Changes in the mineral composition of rocks. Mechanical Weathering: 1.​ Frost Wedging: Water freezes in rock cracks, expanding and splitting the rock. 2.​ Abrasion: Rocks grind against each other, wearing down materials (e.g., sand at beaches). 3.​ Plants and Animals: ○​ Roots grow in rock cracks, splitting them. ○​ Burrowing animals expose rock to air and water. 4.​ Exfoliation: Rocks expand and crack as overlying material erodes, forming domes. Chemical Weathering: 1.​ Hydrolysis: Water reacts with minerals (e.g., feldspar), forming clay. 2.​ Acid Rain: Industrial emissions react with water, accelerating weathering. 3.​ Oxidation: Oxygen reacts with minerals, especially iron, forming rust. Factors Affecting Weathering Rates: 1.​ Surface Exposure: More surface area increases weathering speed. 2.​ Rock Composition: Some rocks resist weathering better than others (e.g., shale weathers easily). 3.​ Climate: ○​ Warm, Wet Climates: Favor chemical weathering. ○​ Cold, Dry Climates: Favor mechanical weathering. Key Takeaway: Weathering, both mechanical and chemical, shapes Earth's landscapes. Its rate and effects depend on rock type, surface exposure, and environmental conditions. ECOLOGY Definition of Ecology: ​ Ecology is the scientific study of interactions among organisms and between organisms and their environment. Vocabulary and Concepts: ​ Key Terms: ○​ Ecology ○​ Biosphere ○​ Species ○​ Population ○​ Community ○​ Ecosystem ○​ Biome Interactions and Interdependence: ​ The biosphere consists of all life-supporting portions of the planet, including land, water, air, and atmosphere. ​ Organisms interact within the biosphere, creating a web of interdependence between living organisms and their environments. Levels of Organization in Ecology: 1.​ Species: Organisms capable of interbreeding and producing fertile offspring. 2.​ Populations: Groups of individuals of the same species in a specific area. 3.​ Communities: Different populations coexisting in a defined area. 4.​ Ecosystems: Living organisms and their physical environment in a particular place. 5.​ Biomes: Groups of ecosystems sharing the same climate and dominant communities. 6.​ Biosphere: The global ecological system integrating all life. Ecological Methods: Ecologists use three main approaches: 1.​ Observing: Initial steps to study ecological patterns. 2.​ Experimenting: Testing hypotheses in labs or natural environments. 3.​ Modeling: Creating models to study complex ecological phenomena, e.g., global warming. Definition and Key Concepts: ​ Ecology: The scientific study of interactions between living things and their environments. ​ Biosphere: The combined portions of Earth where life exists, including land, water, and atmosphere. It constantly changes and demonstrates interdependence among organisms and their surroundings. Ecological Levels of Organization: 1.​ Organism: An individual living entity. 2.​ Population: A group of the same species living in one area. 3.​ Community: Different species living together in an area. 4.​ Ecosystem: Living organisms (biotic) and nonliving components (abiotic) like climate, soil, and water interacting in a specific area. 5.​ Biome: A major regional or global community defined by climate and dominant plant communities.  6.​ Biosphere: The highest level, encompassing all ecosystems on Earth. Ecological Research Methods: 1.​ Observation: The foundational step in ecological studies. 2.​ Experimentation: Hypothesis testing in controlled or natural environments. 3.​ Modeling: Creating representations of systems to study complex phenomena, such as global warming. Earth's Four Interconnected Systems: 1.​ Hydrosphere: Water on Earth, including ice and vapor. 2.​ Atmosphere: The layer of air surrounding the planet. 3.​ Geosphere: Earth's solid surface, including rocks and the sea floor. 4.​ Biosphere: All regions supporting life. Components of Ecosystems: ​ Biotic Factors: Living or once-living organisms (e.g., plants, animals, fungi). ​ Abiotic Factors: Non Living elements (e.g., sunlight, temperature, soil, rocks). Summary: ​ Ecology focuses on interactions between organisms and their environment. ​ Life is organized into hierarchical levels. ​ Biotic factors represent organic components, while abiotic factors are inorganic. 1. Energy Sources ​ The primary energy source for ecosystems is the sun. ​ Photosynthesis: Plants convert sunlight, water (H₂O), and carbon dioxide (CO₂) into glucose (C₆H₁₂O₆) and oxygen (O₂). ○​ Energy is stored in glucose and later in starch. 2. Roles in Ecosystems ​ Producers (Autotrophs): ○​ Photosynthetic organisms: Use sunlight to produce energy. ○​ Chemosynthetic organisms: Utilize chemical compounds for energy. ​ Consumers (Heterotrophs): ○​ Herbivores: Consume plants and fungi. ○​ Omnivores: Eat both plants/fungi and animals. ○​ Carnivores: Eat animals exclusively. ○​ Detritivores: Consume dead organic matter. ○​ Decomposers: Break down organic matter into simpler compounds. 3. Energy Movement ​ Energy moves through ecosystems via trophic structures (levels of the food chain). ○​ Producers → Primary Consumers (Herbivores) → Secondary Consumers (Carnivores/Omnivores) → Tertiary Consumers → Decomposers/Detritivores. ​ Energy is lost as heat at each transfer, with only 10% efficiency between levels. 4. Food Chains and Webs ​ Food Chain: Linear sequence of energy flow. ​ Food Web: Complex and interconnected paths of energy flow with multiple food sources. 5. Energy and Biomass Pyramids ​ Energy Pyramid: Shows energy decrease at higher trophic levels (10% Rule). ​ Pyramid of Numbers: Fewer species at higher trophic levels. ​ Biomass Pyramid: Displays total mass at each trophic level, usually decreasing upward but can be inverted in aquatic ecosystems. 6. Energy Efficiency and Pyramid Shape ​ Energy transfer is highly inefficient, with significant loss as heat.  ​ The pyramid shape illustrates the necessity for a large base of producers to support the ecosystem. Summary of "What Shapes an Ecosystem" Notes Key Concepts 1.​ Climate's Role: Determines long-term conditions that shape ecosystems. 2.​ Biotic and Abiotic Factors: Both living (biotic) and non-living (abiotic) factors influence ecosystem dynamics. 3.​ Community Interactions: Relationships between species, such as competition, predation, and symbiosis, affect ecosystem structure. Key Vocabulary: Biotic/Abiotic Factors, Habitat, Niche, Predation, Symbiosis (Mutualism, Commensalism, Parasitism), Climate, Weather, Greenhouse Effect, and Climate Zones. 1. Climate and Weather ​ Weather: Day-to-day atmospheric conditions. ​ Climate: Long-term averages of temperature and precipitation. ​ Influenced by: ○​ Heat trapped by the atmosphere (e.g., greenhouse gases like CO₂ and methane). ○​ Latitude, wind and ocean currents, precipitation, and landmasses. ​ Greenhouse Effect: Natural retention of heat in the atmosphere by gases that trap solar energy. 2. Latitude and Climate Zones ​ Polar Zones: Cold regions near the poles (66.5°-90° N/S). ​ Temperate Zones: Varying climate based on seasons (23.5°-66.5° N/S). ​ Tropical Zone: Warm, near the equator (0°-23.5° N/S). 3. Heat Transport ​ Unequal heating drives wind and ocean currents, redistributing heat across the biosphere. ​ Landmasses (e.g., mountains) affect wind patterns and local climates. 4. Biotic and Abiotic Factors ​ Biotic Factors: Living components (e.g., trees, animals, bacteria). ​ Abiotic Factors: Non-living elements (e.g., temperature, humidity, soil, sunlight). ​ Habitat: Area where organisms live, shaped by biotic and abiotic elements. 5. Niches and Community Interactions ​ Niche: An organism's role in its environment, including diet, habitat, and ecological relationships. ​ No two species can share the exact same niche. ​ Community Interactions: ○​ Competition: Organisms compete for limited resources. ○​ Predation: One organism hunts another. ○​ Symbiosis: Close relationships between species, with three types: 1.​ Mutualism: Both benefit (e.g., bees and flowers). 2.​ Commensalism: One benefits; the other is unaffected (e.g., barnacles on whales). 3.​ Parasitism: One benefits at the expense of the other (e.g., ticks on hosts). Summary of "World Biomes" Notes Definition of Biomes ​ Biomes are regions with similar physical environments, typically named for their dominant vegetation. ​ Influenced by climate factors: rainfall, temperature, altitude, and latitude. ​ Biome boundaries are often indistinct. Six Major Biomes and Their Characteristics 1.​ Tropical Rain Forests ○​ Equatorial regions with constant temperatures and year-round rainfall. ○​ Dominated by arboreal animals and sparse terrestrial life. 2.​ Tropical Grasslands (Savannas)  ○​ Warm temperatures all year. ○​ Distinct wet and dry seasons, high grasses, and scattered trees/shrubs. ○​ Home to large herbivores. 3.​ Temperate Grasslands ○​ Hot, humid summers and cold winters. ○​ Precipitation as winter snow and heavy spring/summer rain. ○​ Features short/tall grasses and diverse animal life, including burrowing animals. 4.​ Deserts ○​ Defined by low precipitation; can be hot or cold (e.g., Antarctica as a cold desert). ○​ Hot deserts have nocturnal animals and drought-adapted plants. 5.​ Temperate Deciduous Forests ○​ Found in mid-latitude regions with cold winters, hot summers, and significant rainfall/snow. ○​ Features a wide variety of plant and animal life. 6.​ Temperate Rain Forests ○​ Cold winters, hot summers, and abundant rainfall. ○​ Coniferous trees retain needles, which conserve water and shed snow. ○​ Diverse animal life. Other Notable Biomes ​ Taiga (Boreal Forest) ○​ Coniferous forests in high elevations or northern latitudes. ○​ Long, cold winters with snow; animals are cold-adapted. ​ Tundra ○​ Permafrost (permanently frozen ground) limits plant growth. ○​ Near polar regions with small plants and animals adapted to extreme cold. ○​ Birds often migrate from tundra regions during cold seasons. Limiting Factors in Water Biomes: ​ Salinity, dissolved oxygen, sunlight, and temperature. Types of Water Biomes: ​ Freshwater: Includes rivers, streams, lakes, and ponds with low salinity. ​ Saltwater: Includes oceans, estuaries, and seashores, with high salinity. Freshwater Features: ​ Rivers and streams (flowing water) and lakes and ponds (still water). ​ Wetlands (bogs, marshes, and swamps) serve as breeding grounds and support diverse ecosystems. Saltwater Features: ​ Estuaries (mix of salt and freshwater): Fertile areas with high nutrient levels that serve as breeding and nesting grounds. ​ Ocean zones: ○​ Photic Zone: Sunlit, supports abundant plant and animal life. ○​ Aphotic Zone: Dark, specialized animal life, no plants. ○​ Zones by depth include pelagic (open water), benthic (ocean floor), and others like intertidal and neritic zones. Plankton and Phytoplankton: ​ Essential producers in aquatic ecosystems, foundational to food chains. Ecological Succession ​ Gradual changes in species composition over time, categorized into: ○​ Primary Succession: Starts without soil (e.g., after volcanic eruptions or on bare rock). ○​ Secondary Succession: Occurs in areas with existing soil (e.g., after forest fires). ​ Climax Community: Stable ecosystem achieved after succession, varying by biome (e.g., grasses in prairies, cacti in deserts). 2. Limits to Population Growth ​ Limiting Factors: ○​ Density-Dependent: Competition, predation, parasitism, and disease; these intensify with population size. ○​ Density-Independent: Weather, natural disasters, and human activities affect populations irrespective of size. ​ Competition drives resource usage and evolutionary changes, while predation and parasitism regulate populations. 3. Biodiversity ​ Includes ecosystem, species, and genetic diversity. ​ Value: Essential for medicine, agriculture, and ecosystem services. ​ Threats: ○​ Habitat fragmentation, hunting, invasive species, pollution, and climate change. ​ Conservation: Focus on species, habitats, and ecosystem preservation. 4. Global Climate Change ​ Evidence: Rising global temperatures and increased greenhouse gases (e.g., CO2 from fossil fuels). ​ Effects: Rising sea levels, ecosystem changes, extreme weather, and species extinction. 5. Ozone Depletion ​ Caused by substances like CFCs, leading to a “hole” in the ozone layer. ​ Impacts: ○​ DNA damage and impaired photosynthesis in organisms. ○​ Human health risks like skin cancer, cataracts, and immune suppression. 6. Amphibian Decline ​ Linked to habitat destruction, disease, exotic species, contaminants, and UV-B radiation. ​ Impacts all life stages and increases vulnerability to environmental changes.