Science Midterm Review PDF

SCIENCE MIDTERM REVIEW Space Exploration Geocentric model: -In this model the earth is the centre of the universe -This was made by philosopher Aristotle -remember: geo= geographic which is the earth Heliocentric Model: -In this model, the sun is the centre of the universe -Polish astronomer Nic...

SCIENCE MIDTERM REVIEW Space Exploration Geocentric model: -In this model the earth is the centre of the universe -This was made by philosopher Aristotle -remember: geo= geographic which is the earth Heliocentric Model: -In this model, the sun is the centre of the universe -Polish astronomer Nicholas Copernicus made this -Remember Helio=helium, which is an element of the sun Life Of A Star: 1. Nebula – A cloud of gas and dust where stars form. 2. Main Sequence – The longest, most stable phase where nuclear fusion occurs (like our Sun). 3. Red Giant / Supergiant – The star expands as it runs out of fuel. 4. End of Life (Depends on Mass): Low-Mass Stars → Planetary nebula → White dwarf → Black dwarf (eventually). High-Mass Stars → Supernova → Neutron star or Black hole. Other bodies in the Solar System 1. Asteroids – Small, rocky objects mainly found in the Asteroid Belt between Mars and Jupiter. 2. Comets – Made of ice, dust, and gas; have a glowing tail when near the Sun (e.g., Halley’s Comet). 3. Meteoroids, Meteors, and Meteorites: Meteoroids – Small space rocks. Meteors – Burn up in Earth’s atmosphere (shooting stars). Meteorites – Survive the atmosphere and hit Earth. 4. Dwarf Planets – Small planets that don’t clear their orbit (e.g., Pluto, Ceres, Eris). 5. Moons – Natural satellites orbiting planets (e.g., Earth’s Moon, Jupiter’s Europa). Tracking Objects in the Night Sky 1. Early Observations – Ancient civilizations used stars to track time and seasons. 2. Geocentric vs. Heliocentric Models: Geocentric Model – Earth at the center (Ptolemy). Heliocentric Model – Sun at the center (Copernicus, later supported by Galileo). 3. Telescopes – Helped improve observations (Galileo’s discoveries of Jupiter’s moons). 4. Planets’ Motion – Retrograde motion is when planets appear backward due to Earth’s movement. 5. Modern Tracking – Today, we use telescopes, satellites, and computers to study celestial bodies. Triangulation Rocketry and Physics 1. Newton’s Third Law of Motion: States that for every action, there is an equal and opposite reaction. This principle explains how rockets propel themselves by expelling gas downwards to move upwards. 2. Rocket Components: Payload: The cargo the rocket carries, such as satellites or scientific instruments. Propulsion System: Generates thrust; can use solid or liquid fuel. Structure: The body of the rocket, designed to withstand launch forces. 3. Forces on a Rocket: Thrust: The force pushing the rocket upwards. Weight: The force of gravity pulling it down. Drag: Air resistance opposing the rocket’s motion. 4. Rocket Flight Stages: Launch: Rocket ignites, overcoming weight and drag. Ascent: Travels upward through the atmosphere.  Stage Separation: Discarding empty fuel stages to reduce weight. Orbit: Achieving orbit or traveling to a destination. 5. Applications of Rocketry: Used in space exploration, satellite deployment, scientific research, and military technology. 6. Technological Advancements: Improved materials and fuel management enhance safety and efficiency. Hazards of Living in Space 1. Microgravity Effects: Causes muscle loss, bone density reduction, and fluid redistribution in the body. 2. Radiation Exposure: Increased cancer risk from cosmic radiation; spacecraft provide some shielding. 3. Psychological Challenges: Isolation and confinement can lead to stress; support systems help manage mental health. 4. Environmental Hazards: Extreme temperatures require insulated suits; risks from micro-meteoroids and debris. 5. Life Support Systems: Oxygen and water supply is crucial, using recycling; effective waste management is necessary. 6. Training: Astronauts undergo training to adapt to space conditions. Types of Telescopes 1. Optical Telescopes: Use visible light. Refracting: Use lenses; good for planets and stars. Reflecting: Use mirrors; ideal for deep-sky observations. 2. Radio Telescopes: Detect radio waves; use large dish antennas for studying objects like pulsars. 3. Infrared Telescopes:  Observe infrared radiation; useful for studying cool objects and dust clouds. 4. Ultraviolet Telescopes: Detect ultraviolet light; ideal for studying hot stars and galaxies. 5. X-ray and Gamma-ray Telescopes: Observe high-energy radiation; often placed in space due to atmospheric absorption. Doppler Effect 1. Definition: Change in frequency or wavelength of a wave due to the relative motion between the source and the observer. 2. Types: Redshift: Wavelengths stretch when an object moves away, indicating it’s receding (e.g., galaxies moving away). Blueshift: Wavelengths compress when an object moves closer, indicating it’s approaching. 3. Applications: Used in astronomy to study the motion of celestial objects and in technologies like radar and Doppler ultrasound. Space Travel Pros and Cons Pros: 1. Scientific Discovery: Expands knowledge of the universe. 2. Technology Development: Leads to innovations that benefit Earth. 3. International Collaboration: Fosters cooperation among nations. 4. Inspiration: Motivates future generations in STEM. Cons: 1. High Cost: Significant financial investment required. 2. Health Risks: Physical and psychological challenges for astronauts. 3. Environmental Impact: Pollution from rocket launches. 4. Risk of Accidents: Dangers include potential mission failures. Biological Diversity Symbiotic Relationships Definition: Symbiotic relationships are interactions between two different species that live together in close physical proximity, often to the benefit of at least one of the species. Types of Symbiotic Relationships: 1. Mutualism: Both species benefit from the interaction. Example: Bees pollinating flowers while obtaining nectar. 2. Commensalism: One species benefits, and the other is neither helped nor harmed. Example: Barnacles attaching to a whale; the barnacles gain mobility and access to food while the whale is unaffected. 3. Parasitism: One species benefits at the expense of the other. Example: Ticks feeding on the blood of mammals, harming the host in the process. Importance: Symbiotic relationships play a crucial role in ecosystems, affecting population dynamics, resource distribution, and community structure. Heritable vs Non-Heritable Heritable Traits:  Definition: Traits that can be passed from parents to offspring through genetic information. Examples: Eye colour, height, and blood type. Mechanism: Governed by genes and influenced by alleles, which are different gene versions. Non-Heritable Traits: Definition: Traits that cannot be passed from parents to offspring are acquired during an individual’s lifetime. Examples: Skills (like playing an instrument), scars, and learned behaviours. Mechanism: Influenced by environmental factors, experiences, and lifestyle choices rather than genetics. Importance: Understanding the difference between heritable and non-heritable traits helps in fields like genetics, evolutionary biology, and medicine. Variation Between/Within Species ​ Variation Between Species: Definition: Differences in traits or characteristics that distinguish one species from another. Examples: Differences in size, shape, color, and behavior among species, such as between dogs and cats. Importance: Highlights biodiversity and the adaptation of species to different environments. Variation Within Species: Definition: Differences among individuals of the same species. Examples: Variation in traits like coat color in dogs, height in plants, or resistance to diseases in crops.  Causes: Resulting from genetic differences (mutations, alleles) and environmental factors (nutrition, habitat). Discrete vs Countinius Variations Discrete Variation: Definition: Traits that can be categorized into distinct groups or categories with no intermediate values. Examples: Blood type (A, B, AB, O) Flower color (red, white, blue) Characteristics: Typically influenced by single genes and show clear-cut differences. Continuous Variation: Definition: Traits that show a range of values and can take on any value within a given range. Examples: Height in humans Skin color Weight Characteristics: Usually influenced by multiple genes (polygenic inheritance) and environmental factors, resulting in a gradient of traits. Asexual Reproduction ​ Types: 1. Binary Fission: Parent cell divides into two (e.g., bacteria). 2. Budding: A new organism develops from a bud (e.g., yeast, hydra). 3. Fragmentation: Organism splits into fragments, each becoming new individuals (e.g., starfish). 4. Vegetative Propagation: New plants grow from parts of the parent (e.g., runners in strawberries). 5. Spore Formation: Spores develop into new individuals (e.g., fungi). Advantages: Rapid reproduction and energy-efficient. Disadvantages: Lack of genetic diversity makes populations vulnerable. Sexual Reproduction Key Components: 1. Gametes: Male gamete: Sperm Female gamete: Egg (ova) 2. Fertilization: The process where sperm and egg combine to form a zygote. Can be external (e.g., in fish and amphibians) or internal (e.g., in mammals). 3. Zygote Development: The zygote undergoes cell division and develops into an embryo. Advantages: Genetic Diversity: Offspring have a mix of traits from both parents, enhancing adaptability to changing environments. Disadvantages: Energy-Intensive: Requires more time and energy for finding mates and producing gametes. Slower Population Growth: Compared to asexual reproduction, sexual reproduction usually results in fewer offspring at a time. DNA, Genes, and Chromosomes DNA (Deoxyribonucleic Acid): Structure: Double helix made of nucleotides (phosphate, sugar, nitrogenous base). Function: Carries genetic information. Genes: Definition: Segments of DNA that encode instructions for proteins. Role: Located on chromosomes; can have different forms called alleles. Chromosomes: Structure: Coiled DNA and proteins; humans have 46 chromosomes (23 pairs). Types: Autosomes: 22 pairs of non-sex chromosomes. Sex Chromosomes: Determine sex (X and Y in humans). Cell Division Definition: Cell division is the process through which a parent cell divides to produce daughter cells, facilitating growth, tissue repair, and reproduction. Types of Cell Division: 1. Mitosis: Purpose: To produce two genetically identical daughter cells for growth and tissue repair. Process: Involves one division cycle with several stages:  Prophase: Chromosomes condense and become visible; the nuclear membrane begins to break down. Metaphase: Chromosomes align at the cell’s equator. Anaphase: Sister chromatids are pulled apart to opposite poles of the cell. Telophase: Nuclear membranes reform around each set of chromosomes, and the cell prepares to split. Outcome: Two diploid daughter cells, each with the same chromosome number as the parent cell. 2. Meiosis: Purpose: To produce gametes (sperm and egg) for sexual reproduction, leading to genetic diversity. Process: Involves two successive division cycles (Meiosis I and II) with unique stages: Meiosis I: Homologous chromosomes are separated, reducing the chromosome number by half. Meiosis II: Similar to mitosis, where sister chromatids are separated. Outcome: Four haploid daughter cells, each with half the chromosome number of the original cell, introducing genetic variation through independent assortment and crossing over. Importance: Mitosis: Vital for growth, development, and the maintenance of tissues. Meiosis: Essential for sexual reproduction, contributing to genetic diversity in populations, which is important for adaptation and evolution. Patterns of Inheritance Key Patterns: 1. Mendelian Inheritance: Traits can be dominant (expressed with one allele) or recessive (expressed only with two alleles). 2. Incomplete Dominance: Neither allele is completely dominant; traits blend.  Example: Red and white snapdragons produce pink flowers. 3. Codominance: Both alleles are expressed. Example: Type AB blood shows both A and B antigens. 4. Polygenic Inheritance: Traits are controlled by multiple genes, resulting in a range of phenotypes (e.g., height, skin color). 5. Sex-Linked Inheritance: Traits linked to sex chromosomes, often more common in one sex (e.g., color blindness). Extintion vs Extirpation Extinction is when an organism does not exist anywhere in the universe. Extirpation is when an organism does not exist in a local area but continues to exist in a some other area. Biotechnology Definition: Biotechnology uses living organisms or their products to develop technologies for various applications. Key Applications: Medical: Development of vaccines, antibiotics, and gene therapies through recombinant DNA technology. Agricultural: Creation of genetically modified organisms (GMOs) for traits like pest resistance and increased yield; use of biopesticides and biofertilizers. Environmental: Bioremediation using microorganisms to clean up contaminants; biological waste treatment. Techniques: Recombinant DNA Technology: Combining DNA from different organisms. CRISPR-Cas9: A precise gene-editing tool. Matter and Chemical Change WHMIS Symbols Organizing Matter evaporation:To change from a liquid state to a gaseous state. solidification: The transition from a liquid state to a solid state. sublimation: To change from a solid state directly to the gaseous state without going through a liquid phase. melting: The change of state from a solid to a liquid. Pure Substances and Mixtures Pure Substances:  Consist of only one type of particle and have uniform properties throughout. Elements: Cannot be broken down into simpler substances (e.g., oxygen, gold). Compounds: Formed when two or more elements chemically combine in fixed proportions (e.g., water, carbon dioxide). Mixtures: Combinations of two or more substances that retain their individual properties. Homogeneous Mixtures: Have a uniform composition and appearance (e.g., saltwater, air). Heterogeneous Mixtures: Contain visibly different substances or phases (e.g., salad, oil and water). Distinguishing Features: Pure substances have consistent properties and compositions, while mixtures can vary in composition and do not have uniform properties. Physical and Chemical Properties Physical Properties: Characteristics of a substance that can be observed or measured without changing its identity. Examples include: Color: The visual appearance of the substance. Odor: The scent of the substance. Boiling Point: The temperature at which a substance changes from a liquid to a gas. Melting Point: The temperature at which a substance changes from a solid to a liquid. Density: The mass per unit volume of a substance. Chemical Properties: Characteristics that describe a substance’s ability to undergo chemical changes or reactions. Examples include: Reactivity: How readily a substance reacts with other substances (e.g., acids, bases). Flammability: The ability of a substance to burn in the presence of oxygen.  pH: The acidity or basicity of a substance. Distinction: Physical properties can be observed without altering the substance’s chemical composition, while chemical properties can only be observed during a chemical reaction that changes the substance. Physical and Chemical Changes Physical Changes: Changes that affect a substance’s physical properties without altering its chemical composition. Examples include: State changes (melting, freezing). Changes in shape or size (cutting, dissolving). Mixture formation (mixing substances). Chemical Changes: Changes that result in the formation of new substances with different properties. Indicators include: Color change (e.g., rust). Gas production (e.g., bubbling). Temperature change (e.g., combustion). Precipitate formation (e.g., solid from a solution). Distinction: Physical changes can often be reversed, while chemical changes usually produce new substances that cannot easily revert to their original forms. Bohr’s Diagram Organizing the Elements The organization of elements is represented in the Periodic Table, structured by atomic number and chemical properties. Periods: Horizontal rows indicate energy levels; moving left to right, elements transition from metallic to nonmetallic. Groups: Vertical columns contain elements with similar properties due to the same number of valence electrons. For example: Group 1: Alkali metals, highly reactive with one valence electron. Group 17: Halogens, very reactive nonmetals with seven valence electrons. Group 18: Noble gases, inert with full valence shells. Types of Elements: Metals are conductive and malleable, nonmetals are insulative and brittle, and metalloids have mixed properties. Understanding the Periodic Table The Periodic Table organizes elements based on their atomic structure and properties, providing valuable information for understanding chemical behavior. Atomic Number: Each element is identified by its atomic number, which indicates the number of protons in the nucleus. Element Symbols: Each element has a unique one- or two-letter symbol (e.g., H for hydrogen, O for oxygen) that represents its name. Groups and Periods: Groups: Vertical columns that categorize elements with similar chemical properties and the same number of valence electrons (e.g., alkali metals in Group 1). Periods: Horizontal rows that show elements with increasing atomic number and varying properties. Metal, Nonmetal, and Metalloid Regions: The table visually separates metals, nonmetals, and metalloids, helping to identify their characteristics: Metals: Conductive and malleable. Nonmetals: Insulative and brittle. Metalloids: Exhibit properties of both metals and nonmetals. Trends in the Periodic Table: Reactivity: Varies among groups; for instance, alkali metals are highly reactive. Atomic Size: Generally increases down a group and decreases across a period. Electronegativity: Tends to increase across a period and decrease down a group. Atomic Mass and Atomic Number Atomic Number: The number of protons in an atom’s nucleus, defining the element and found in the top left corner of its box (e.g., hydrogen: 1, carbon: 6).  Atomic Mass: The average mass of an element’s isotopes, measured in atomic mass units (amu), located in the bottom left corner of its box (e.g., carbon: approximately 12 amu). Key Points: The atomic mass is usually higher than the atomic number, and isotopes have the same atomic number but different atomic masses due to varying neutrons. Protons, Neutrons, and Electrons Protons: Positively charged particles in the nucleus; the number of protons determines the atomic number and identifies the element (e.g., hydrogen has 1 proton). Neutrons: Neutral particles in the nucleus that contribute to atomic mass; the number of neutrons can vary in isotopes (e.g., carbon-12 has 6 neutrons, carbon-14 has 8). Electrons: Negatively charged particles that orbit the nucleus; usually equal to the number of protons in a neutral atom (e.g., carbon has 6 electrons). Manipulated vs Responding variables The three types of variables are manipulated, control, and responding. A manipulated variable is changed by the scientist because it is what is being tested. Control variables remain the same throughout an experiment. Responding variables change as a result of the manipulated variable.