Science

Biology Review

Key Definitions

  • Abiotic: Non-living components of an ecosystem, such as water, sunlight, soil, and minerals, which play a crucial role in supporting life.

  • Biotic: Living components of an ecosystem, including plants, animals, fungi, and microorganisms, which interact with each other and the abiotic components.

  • Population: A group of organisms of the same species living in a particular area, representing the smallest unit of biological organization that can reproduce.

  • Community: An assemblage of multiple populations of different species that interact with one another in a defined area, forming relationships that can be competitive, predatory, or symbiotic.

  • Ecosystem: The complex interactions between both biotic and abiotic factors in a particular environment, wherein energy and nutrients circulate through food webs.

  • Producer: Organisms, primarily plants and certain microorganisms, that create their own food through photosynthesis or chemosynthesis, forming the base of the food web.

  • Consumer: Organisms that depend on consuming other organisms for energy, including herbivores, carnivores, and omnivores.

  • Decomposer: Organisms, such as bacteria and fungi, that break down dead organic material and waste products, returning essential nutrients to the soil.

  • Food Web: A complex network of interlinked food chains that illustrates how energy flows through an ecosystem, highlighting the interdependence of organisms.

  • Biodiversity: The variety of life forms within an ecosystem, including the diversity of species, genetic variability, and the variety of ecosystems present, crucial for ecosystem resilience and stability.

Producers, Consumers, and Decomposers

  • Grass: A primary producer (P) that captures solar energy through photosynthesis and forms the base of the food chain.

  • Cows: Secondary consumers (C) that are primarily herbivores consuming grasses and shrubs.

  • Bacteria: Decomposers (D) that play an integral role in nutrient cycling by breaking down dead organic material.

  • Fish: Consumers (C) that can be primary consumers (eating producers) or secondary consumers (eating other consumers).

  • Spider Plant: A producer (P) that produces oxygen and food via photosynthesis, contributing to the habitat.

Herbivores, Carnivores, and Omnivores

  • Humans: Omnivores (O) that consume a varied diet consisting of both plant and animal sources, playing a unique ecological role.

  • Frogs: Carnivores (C) that primarily eat insects and other small organisms, contributing to pest control.

  • Deer: Herbivores (H) that primarily consume leaves, fruits, and grass, impacting vegetation growth.

  • Sharks: Carnivores (C) at the top of the food chain, helping regulate fish populations to maintain balance in marine ecosystems.

  • Tadpoles: Herbivores (H) that graze on algae and plant matter, playing a role in aquatic ecosystems.

Food Web

  • Producers: Grass, Shrubs.

  • Primary Consumers: Deer, Rabbits, Mice.

  • Secondary Consumers: Snakes, Frogs, Owls.

  • Tertiary Consumers: Hawks, Mountain Lions.

  • Decomposer: Vultures (feeds on dead animals).

  • Arrows indicate the flow of energy from producers, through primary and secondary consumers, to decomposers, illustrating ecosystem interdependencies.

Impact of Removing Mice

  • The removal of mice would lead to larger declines in populations of secondary consumers like snakes, owls, and hawks, who rely on them for food.

  • Overgrazing by deer and insufficient seed dispersal could lead to an overgrowth of grass and shrubs, disrupting the ecological balance.

Earth Spheres

  • Atmosphere: Composed of gases including oxygen and nitrogen, crucial for life and climate regulation.

  • Lithosphere: The solid, rocky outer layer of the Earth, including soil and minerals, which supports terrestrial life.

  • Hydrosphere: Encompasses all water found on Earth's surface, vital for all forms of life, affecting weather and climate.

  • Biosphere: The global sum of all ecosystems, where life exists, incorporating the other spheres.

Carbon and Nitrogen Cycles

  • Carbon Cycle: Involves the absorption of carbon dioxide by plants during photosynthesis, converting it into oxygen and glucose; animals respire, releasing CO₂ back into the atmosphere, maintaining balance in the ecosystem.

  • Nitrogen Cycle: Nitrogen from the atmosphere is converted into nitrates by nitrogen-fixing bacteria in the soil; plants absorb these nitrates, and when they decompose, nitrogen returns to the soil, completing the cycle.

Photosynthesis and Cellular Respiration

  • Photosynthesis: The process by which plants convert sunlight into chemical energy stored in glucose, using water and carbon dioxide, producing oxygen as a byproduct.

  • Cellular Respiration: The metabolic process in which organisms break down glucose in the presence of oxygen to release energy, carbon dioxide, and water, essential for sustaining life.

Greenhouse Effect and Climate Change

  • Greenhouse Effect: The natural process in which certain gases, including carbon dioxide and methane, trap heat in the atmosphere, keeping the Earth warm enough to sustain life.

  • Climate Change: Refers to long-term alterations in temperature and typical weather patterns, largely driven by human activities that increase greenhouse gas emissions. This leads to severe consequences like habitat loss, species extinction, and rising sea levels.

Chemistry Review

Physical and Chemical Properties

  • Lustre: A physical property describing how shiny or reflective a substance is.

  • Hardness: Indicates a material's resistance to scratching; measured by various scales including Mohs hardness scale.

  • Combustibility: A chemical property indicating the ability of a substance to ignite or burn when exposed to heat or flame.

  • Viscosity: A physical property reflecting a fluid's resistance to flow; important in determining how substances interact in different states (liquid vs. gas).

Classification of Matter

  • Substance Type: Classifies how a material is structured.

  • Sodium chloride: A compound where sodium and chlorine atoms are chemically bonded to form a stable compound.

  • Sugar in water: A homogeneous mixture where the sugar is evenly distributed, resulting in a uniform composition throughout.

  • Mixed vegetables: A heterogeneous mixture where the individual components are distinct and not uniformly mixed.

Changes in Matter

  • Physical Change: Alterations where no new substances are formed; examples include phase changes like ice melting or boiling water.

  • Chemical Change: Occurs when substances react to form new materials; examples include burning paper or rusting iron.

Atomic Structure

  • Particle: Refers to basic units of matter.

    • Proton: Located in the nucleus; has a mass of 1 amu and a positive charge.

    • Neutron: Also in the nucleus; has a mass of 1 amu but is neutral (no charge).

    • Electron: Found outside the nucleus in electron shells; nearly massless (~0 amu) and carries a negative charge.

Physics Review

Key Formulas

  • Ohm’s Law: V = I * R, where V is voltage, I is current, and R is resistance.

  • Power: P = V * I, defines the rate at which electrical energy is transferred.

  • Efficiency: Efficiency = (Useful Energy Output / Energy Input) * 100.

Static Electricity

  • Opposite charges attract, while like charges repel. This fundamental principle explains various electrical phenomena from everyday static shocks to the behavior of charged particles in electric fields.

Series vs. Parallel Circuits

  • Characteristic: Compares series and parallel circuits.

    • Series: One path for current flow; if one component fails, the entire circuit is interrupted.

    • Parallel: Multiple paths for current flow; if one component fails, others can still function, allowing continuous operation.

Astronomy Review

Solar System

  • Inner Planets: Mercury, Venus, Earth, and Mars; these are rocky planets with solid surfaces.

  • Outer Planets: Jupiter, Saturn, Uranus, and Neptune; known as gas giants, they have thick atmospheres and do not have a solid surface.

Key Facts

  • Largest planet: Jupiter, known for its massive size and great red spot.

  • Closest to the Sun: Mercury, which has extreme temperature variations due to its thin atmosphere.

  • Earth’s rotation: Takes approximately 24 hours, resulting in day and night cycles.

  • Earth’s revolution: Completes one orbit around the sun in about 365.25 days, leading to the concept of a year.