Sci Quiz Bee Rev Lmao Lmao Grade 7 Science PDF

Science Review woah Grade 7 Science 1.​ Life Processes in Living Organisms ○​ Nutrition: ​ Autotrophs (e.g., plants) produce their own food via photosynthesis (light energy converts into chemical energy). Heterotrophs (e.g., animals) rely...

Science Review woah Grade 7 Science 1.​ Life Processes in Living Organisms ○​ Nutrition: ​ Autotrophs (e.g., plants) produce their own food via photosynthesis (light energy converts into chemical energy). Heterotrophs (e.g., animals) rely on consuming other organisms for food. ​ In humans, digestion occurs in stages, from ingestion to the mechanical and chemical breakdown of food in the mouth, stomach, and intestines. ​ Photosynthesis is critical for life on Earth as it is the foundation of most food chains. ○​ Respiration: ​ Aerobic Respiration uses oxygen to break down glucose, yielding carbon dioxide, water, and energy (ATP). ​ Anaerobic Respiration occurs without oxygen (e.g., in muscles during intense activity), producing less energy and creating byproducts like lactic acid in animals or ethanol in yeast. ○​ Transport: ​ In animals, the circulatory system, including the heart, blood, and blood vessels, circulates oxygen, nutrients, and waste products. ​ In plants, the transport system consists of xylem (transports water) and phloem (transports food). ○​ Excretion: ​ Kidneys in humans filter blood to remove waste products and excess substances, maintaining homeostasis. ​ Plants expel waste through transpiration (loss of water vapor) and exudates from roots. 2.​ Reproduction in Plants and Animals ○​ Asexual Reproduction: ​ Budding (e.g., in yeast or hydra): A new organism grows from the body of the parent organism. ​ Binary Fission (e.g., bacteria): One cell divides to form two identical cells. ​ Vegetative Propagation (e.g., in plants like strawberries): New plants grow from parts of the parent plant like roots, stems, or leaves. ○​ Sexual Reproduction: ​ In plants, the flower contains male (stamens) and female (pistil) reproductive organs. Pollination leads to fertilization and seed production. ​ In humans, the male and female reproductive systems produce sperm and eggs, respectively. Fertilization occurs when sperm meets egg, forming a zygote that develops into an embryo. 3.​ Diversity in Living Organisms  ○​ Classification: ​ The classification of living organisms helps scientists identify and group species based on shared characteristics. ​ The binomial nomenclature system gives each species a two-part scientific name (e.g., Homo sapiens for humans). ​ The Five Kingdoms: ​ Monera: Single-celled organisms, mostly bacteria. ​ Protista: Unicellular eukaryotes like amoeba, algae. ​ Fungi: Yeast, mold, and mushrooms. ​ Plantae: Multicellular, autotrophic organisms like flowering plants. ​ Animalia: Multicellular, heterotrophic organisms, such as humans, birds, and insects. ○​ Importance: Helps understand evolutionary relationships and ecological roles. 4.​ Weather and Climate ○​ Weather: ​ Weather is short-term atmospheric conditions (e.g., rainfall, temperature, wind speed). ​ Tools like thermometers (for temperature), barometers (for air pressure), and anemometers (for wind speed) help measure and predict weather conditions. ○​ Climate: ​ Climate is the long-term pattern of weather in a region. Factors that affect climate include latitude, altitude, ocean currents, and wind patterns. ​ Tropical, temperate, and polar are examples of climate zones that determine what plants and animals can thrive in those regions. 5.​ Matter and its Properties ○​ States of Matter: ​ Solid: Has a fixed shape and volume with particles tightly packed in a regular pattern. ​ Liquid: Has a fixed volume but takes the shape of its container; particles are close but can move past each other. ​ Gas: Has neither fixed shape nor volume; particles are far apart and move freely. ​ Plasma: A state found in stars, where atoms are ionized, and electrons are free. ○​ Matter Changes: ​ Physical Changes: Do not result in new substances (e.g., melting, boiling). ​ Chemical Changes: Result in the formation of new substances (e.g., burning, rusting). Grade 8 Science Cell Structure and Functions ○​ Cell Organelles: ​ Nucleus: Contains the cell's genetic material (DNA) and controls cell activities. ​ Mitochondria: Energy production via cellular respiration, converting glucose into ATP. ​ Endoplasmic Reticulum (ER): Smooth ER synthesizes lipids; rough ER has ribosomes for protein synthesis. ​ Golgi Apparatus: Packages proteins for transport within or outside the cell. ​ Chloroplasts (in plants): Contain chlorophyll, which helps plants perform photosynthesis. ○​ Cell Division: ​ Mitosis: Cell division that results in two genetically identical daughter cells. Occurs for growth, repair, and asexual reproduction. -Mitosis is the process by which a eukaryotic cell divides to produce two genetically identical daughter cells. It is essential for growth, repair, and asexual reproduction. The steps in mitosis are: 1.​ Interphase: The cell is in its resting phase, preparing for division. DNA is replicated. 2.​ Prophase: Chromosomes condense and become visible. The nuclear membrane begins to break down, and the spindle fibers begin to form. 3.​ Metaphase: Chromosomes align along the center of the cell, known as the metaphase plate. 4.​ Anaphase: The centromeres split, and sister chromatids (the halves of each chromosome) are pulled to opposite sides of the cell. 5.​ Telophase: Chromatids reach opposite poles, and a new nuclear membrane forms around each set of chromosomes, leading to the formation of two nuclei. 6.​ Cytokinesis: The cytoplasm divides, resulting in two distinct daughter cells. ​ Meiosis: Reduces the chromosome number by half, producing gametes (sperm and egg) for sexual reproduction. -Meiosis occurs in sex cells (gametes) and reduces the chromosome number by half, creating four genetically unique daughter cells. It includes two rounds of division: 1.​ Interphase: Similar to mitosis, DNA is replicated.  2.​ Prophase I: Chromosomes condense and homologous chromosomes pair up. Crossing-over (exchange of genetic material) occurs. 3.​ Metaphase I: Homologous chromosome pairs line up in the middle. 4.​ Anaphase I: Homologous chromosomes are pulled apart to opposite poles. 5.​ Telophase I: Chromosomes arrive at the poles and the cell divides (cytokinesis). 6.​ Prophase II: Chromosomes condense again. 7.​ Metaphase II: Chromosomes align at the center. 8.​ Anaphase II: Sister chromatids are pulled apart. 9.​ Telophase II: New nuclear membranes form around each set of chromosomes, and cytokinesis results in four non-identical daughter cells (gametes). Motion and Force ○​ Force and Types: ​ Contact Forces: Friction, tension, and normal force. ​ Non-contact Forces: Gravity, electromagnetic force, and nuclear force. ​ Gravity: The force that attracts objects toward the center of the Earth (or any other celestial body). ​ Friction: A force that opposes motion between two surfaces. ○​ Newton’s Laws: ​ 1st Law (Inertia): An object will not change its state of motion unless acted upon by an external force. ​ 2nd Law (F=ma): The force applied on an object is equal to its mass times its acceleration. ​ 3rd Law (Action = Reaction): For every action, there is an equal and opposite reaction. ○​ Speed and Acceleration: ​ Speed = Distance/Time. ​ Acceleration = Change in velocity/time taken. Energy and its Forms ○​ Energy Types: ​ Kinetic Energy: Energy of motion (e.g., a moving car). ​ Potential Energy: Stored energy (e.g., a book on a shelf has potential energy due to gravity). ​ Thermal Energy: Energy related to the temperature of a substance (heat). ○​ Energy Transfer and Conservation: ​ Energy can be transformed from one form to another (e.g., chemical to kinetic in a car engine).  ​ The Law of Conservation of Energy states that energy cannot be created or destroyed, only converted. Electricity and Magnetism ○​ Electric Circuits: ​ Series Circuit: Components connected end-to-end; if one component fails, the whole circuit is broken. ​ Parallel Circuit: Components connected in multiple branches; if one fails, the rest continue to function. ○​ Ohm’s Law: ​ V = IR, where V is voltage, I is current, and R is resistance. Ohm's Law: States that the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance. Formula: ○​ V=I×RV = I \times RV=I×R ○​ Where: ​ VVV = Voltage (Volts) ​ III = Current (Amperes) ​ RRR = Resistance (Ohms) Explanation: If the voltage increases, the current increases if the resistance remains constant. If the resistance increases, the current decreases if the voltage remains constant. Ohm’s Law is fundamental in understanding electrical circuits, ensuring they are properly designed to function efficiently without overloads. Magnetic Fields: ​ Created by moving electric charges, such as electrons in atoms. ​ Magnets have north and south poles, and like poles repel while opposite poles attract. Grade 9 Science 1.​ Atoms and Molecules  ○​ Atomic Structure: ​ Protons (positive charge) and Neutrons (neutral charge) make up the nucleus. ​ Electrons (negative charge) orbit the nucleus in energy levels. ○​ Chemical Bonding: ​ Ionic Bonding: Occurs between metals and non-metals, where electrons are transferred (e.g., sodium chloride). ​ Covalent Bonding: Occurs between non-metals, where electrons are shared (e.g., water). 2.​ Chemical Reactions ○​ Types of Reactions: ​ Synthesis Reaction: Two or more reactants combine to form one product (e.g., A + B → AB). ​ Decomposition Reaction: A compound breaks down into simpler substances (e.g., AB → A + B). ​ Exothermic Reactions: Release energy (e.g., combustion). ​ Endothermic Reactions: Absorb energy (e.g., photosynthesis). 3.​ The Human Body and Health ○​ Systems: ​ Circulatory System: The heart pumps blood, which carries oxygen and nutrients to cells, while removing waste products. ​ Digestive System: Breaks down food into nutrients for absorption into the bloodstream. ​ Respiratory System: Exchanges gases (oxygen in, carbon dioxide out) via the lungs. Nose: ​ Air enters the body through the nose, where it is filtered by cilia and mucus. It is then warmed and moistened before entering the lungs. Trachea (Windpipe): ​ A tube that carries air from the nose/mouth to the bronchi. It is lined with cilia and mucus to trap dust and particles. Bronchi: ​ The two main branches of the trachea that lead to each lung. They further divide into smaller bronchioles inside the lungs. Lungs: ​ Organs where gas exchange (oxygen and carbon dioxide) occurs. The right lung has three lobes, and the left lung has two.  Alveoli: ​ Tiny air sacs in the lungs where oxygen is exchanged with carbon dioxide in the blood. The walls are thin to allow easy diffusion. Diaphragm: 4.​ A muscle below the lungs that contracts and relaxes to help in breathing. When it contracts, it creates a vacuum that draws air into the lungs. ○​ Diseases: ​ Infectious Diseases: Caused by pathogens (bacteria, viruses, fungi). ​ Non-communicable Diseases: Chronic conditions not caused by infections (e.g., diabetes, heart disease) 5.​ Force and Pressure ○​ Pressure: ​ Pressure = Force/Area. Pressure increases when force is applied over a smaller area. ​ Atmospheric pressure and water pressure increase with depth. Types of Forces Contact Forces: Forces that occur when objects are in physical contact with each other. ○​ Friction: The resistance to motion that occurs when two surfaces slide against each other. It can be useful (e.g., walking, braking) or detrimental (e.g., wear and tear of machines). ○​ Tension: The force transmitted through a string, rope, or cable when it is pulled tight. It is the force exerted in opposite directions at the ends of the rope. ○​ Normal Force: The force exerted by a surface perpendicular to the object resting on it. It prevents objects from falling through surfaces. ○​ Elastic Force: The force exerted by a material when it is stretched or compressed (e.g., springs). Non-contact Forces: Forces that act over a distance without physical contact. ○​ Gravitational Force: The attractive force between two objects due to their mass. This is the force that keeps us grounded on Earth and governs the motion of celestial bodies. ○​ Magnetic Force: The force exerted by magnets on certain materials. It can either attract or repel depending on the poles. ○​ Electrostatic Force: The force between charged particles. Opposite charges attract, while like charges repel.  ○​ Nuclear Force: The force that holds protons and neutrons together in the nucleus of an atom. 6.​ Earth and Universe ○​ Earth’s Layers: ​ The Earth’s crust is made of tectonic plates that shift and cause geological events like earthquakes. Crust: ○​ The outermost layer of the Earth. It is solid and thin compared to the other layers. The crust includes the land (continental crust) and the ocean floors (oceanic crust). Mantle: ○​ Located beneath the crust, it is composed of semi-solid rock. It is divided into the upper mantle and the lower mantle. Convection currents in the mantle drive tectonic plate movements. Outer Core: ○​ A liquid layer made mostly of iron and nickel. The movement of molten metals in the outer core generates the Earth's magnetic field. Inner Core: ○​ The innermost layer of the Earth, composed mostly of solid iron and nickel. Despite the high temperatures, the pressure keeps it in a solid state. ○​ The Solar System: ​ The Sun is the center of the solar system. Planets orbit it due to its gravitational pull. The solar system also includes moons, asteroids, and comets. The Sun: ​ The central star of the solar system that provides energy to sustain life on Earth. It consists mainly of hydrogen and helium and produces energy through nuclear fusion. Planets: ​ The solar system contains eight planets:  ○​ Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Each planet has unique characteristics such as size, composition, and number of moons. Dwarf Planets: ​ Smaller bodies like Pluto and Eris, which are considered part of the solar system but do not dominate their orbit. Moons: ​ Natural satellites that orbit planets. Earth has one moon, while Jupiter has 79, including the largest moon in the solar system, Ganymede. Asteroids and Comets: ​ Asteroids are rocky bodies mainly found in the asteroid belt between Mars and Jupiter, while comets are icy bodies that develop a tail when they approach the Sun. Grade 10 Science 1.​ Acids, Bases, and Salts ○​ Acid-Base Reactions: ​ Neutralization: Acid reacts with a base to form water and a salt (e.g., HCl + NaOH → NaCl + H₂O). ○​ Salts: ​ Formed when an acid reacts with a base (e.g., sodium chloride from hydrochloric acid and sodium hydroxide). 2.​ Metals and Non-Metals ○​ Properties: ​ Metals: Good conductors of heat and electricity, malleable, ductile, and typically shiny (e.g., iron, copper). ​ Non-metals: Poor conductors, often brittle, and have lower melting and boiling points (e.g., sulfur, oxygen). 3.​ Carbon and its Compounds ○​ Organic Chemistry: ​ Study of carbon compounds, including hydrocarbons (alkanes, alkenes, alkynes) and functional groups (alcohols, acids). ○​ Carbon Cycle: ​ Describes how carbon is exchanged between the atmosphere, oceans, soil, and living organisms. 4.​ Periodic Table and Periodicity ○​ Trends in the Periodic Table: ​ Elements are arranged by increasing atomic number, showing trends in atomic size, reactivity, and electron configuration.  ○​ Group and Period Trends: ​ Group: Elements in the same vertical column share similar properties (e.g., alkali metals). ​ Period: Elements in the same horizontal row show gradual changes in properties. 5.​ Environmental Science ○​ Sustainability: ​ Practices like recycling, conservation of resources, and renewable energy sources help reduce human impact on the environment. ○​ Pollution: ​ Air Pollution: Caused by industrial emissions, vehicle exhaust, and deforestation. ​ Water Pollution: Contaminants from industrial, agricultural, and domestic waste. 6.​ Human Reproductive System: ○​ Male: Includes the testes (produce sperm), epididymis (stores sperm), vas deferens, and penis. Sperm is produced in the testes and delivered via the urethra. ○​ Female: Includes the ovaries (produce eggs), fallopian tubes (where fertilization occurs), uterus (where the embryo develops), and vagina (birth canal). 7.​ Volcanoes: ○​ Volcanoes are openings in the Earth's crust through which molten rock (lava), gas, and ash erupt. They form when magma from the mantle rises through weak spots in the crust. Types of volcanoes include shield volcanoes, composite volcanoes, and cinder cone volcanoes. 8.​ Tectonic Plates: ○​ The Earth’s lithosphere is divided into large, rigid plates known as tectonic plates. These plates float on the semi-fluid asthenosphere beneath them. Movement of these plates leads to geological phenomena like earthquakes and mountain building. 9.​ Plate Movements: ○​ Divergent Boundaries: Plates move apart (e.g., mid-ocean ridges). ○​ Convergent Boundaries: Plates collide (e.g., subduction zones). ○​ Transform Boundaries: Plates slide past each other (e.g., San Andreas Fault). 10.​Human Respiratory System (Diseases): ○​ Common respiratory diseases include asthma (airway constriction), pneumonia (lung infection), tuberculosis (bacterial infection), and chronic obstructive pulmonary disease (COPD), typically caused by smoking. 11.​Hormonal Regulation: ○​ Hormones are chemical messengers that regulate bodily functions. The endocrine system produces hormones that control growth, metabolism, and sexual function. The pituitary gland controls other glands, and the thyroid regulates metabolism. 12.​Central Dogma of Molecular Biology:  ○​ Describes the flow of genetic information: DNA → RNA → Protein. DNA is transcribed into mRNA, which is then translated into protein, the functional units of cells. 13.​Evolution: ○​ The process by which organisms change over time through variations in traits, natural selection, and genetic mutations. Over generations, these changes lead to the adaptation of species to their environment. 14.​Electromagnetic Radiation: ○​ Refers to the energy transmitted through space via electromagnetic waves. This includes visible light, radio waves, microwaves, X-rays, and gamma rays. These waves differ in frequency and wavelength. 15.​Light: ​ Light is electromagnetic radiation visible to the human eye. It behaves both as a particle (photon) and a wave. The spectrum includes all wavelengths from violet (short) to red (long), with white light being a mixture of all colors.