Matter, Forces, and Motion

• Substances are made from different types of atoms that form molecules
• Each pure substance possess physical/chemical properties that help distinguish it

States of Matter

• Gases and liquids consist of molecules or inert atoms in constant motion
• Liquid molecules are in continuous contact
• Gas molecules are widely spaced except during collisions
• Solid molecules are closely spaced, vibrating in fixed positions
• Solids can be made of molecules or crystals
• Changes of state happen when temperature or pressure changes
• Heat is thermal energy, while cold refers to the absence of heat

Forces and Motion

• For interacting objects, the force exerted by the first on the second is equal in strength and opposite in direction to the force exerted by the second on the first, according to Newton's 3rd Law
• An object's motion is determined by the sum of the forces acting on it
• Motion changes if the total force on an object is not zero
• The greater the mass of an object, the greater the force needed to change its motion
• For a given object, a larger force results in a larger change in motion
• Motion energy is kinetic energy, proportional to the mass of a moving object and increasing with speed
• Potential energy is stored energy

Temperature and Energy Transfer

• Temperature measures the average kinetic energy of particles in matter
• The relationship between temperature and total energy depends on the type, state, and amount of matter
• Changes in an object's motion energy must be accompanied by another energy change
• Potential energy can convert to kinetic energy
• The amount of energy needed to change the temperature of matter depends on factors like size and environment
• Energy transfers from hotter to colder regions or objects
• Interacting objects exert forces on each other, causing energy transfer

Waves

• A simple wave has a repeating pattern characterized by wavelength, frequency, and amplitude
• Wavelength is the distance between waves
• Frequency measures how often a repeated pattern occurs
• Amplitude measures change in a period
• Sound waves require a medium for transmission
• Light is reflected, absorbed, or transmitted when it shines on an object, depending on the object's material and the light's frequency (color)
• Light travels in straight lines, bending at surfaces between different transparent materials
• A wave model of light explains brightness, color, and frequency-dependent bending
• Light can travel through space, so it cannot be a matter wave like sound or water
• Digitized signals sent as wave pulses offer a reliable way to encode and transmit information

Cells

• All living things are made of cells, the smallest unit of life
• Organisms can be unicellular or multicellular
• Cells contain special structures responsible for their functions
• Cell membrane controls what enters and leaves the cell
• In multicellular organisms, the body is a system of interacting subsystems
• Tissues and organs are groups of cells working together for specialized body functions
• Sense receptors respond to different inputs, transmitting signals to the brain via nerve cells
• The brain processes these signals, resulting in behaviors and memories

Photosynthesis and Energy

• Plants, algae, and some microorganisms use light energy to make sugar (food) from carbon dioxide and water through photosynthesis, releasing oxygen
• Sugars are either used immediately or stored for growth and later use
• Food undergoes chemical reactions to break down and rearrange into new molecules in order to support growth or to release energy

Ecosystems

• Organisms and populations depend on environmental interactions
• Organisms or populations with similar needs may compete for resources
• Growth of population are limited by the access to resources
• Food webs model matter and energy transfers between producers, consumers, and decomposers
• Matter transfers into and out of the physical environment at all levels
• Decomposers recycle nutrients from dead organisms back to the soil or water
• Atoms within organisms are repeatedly cycled between living and nonliving components
• Ecosystems are dynamic, with characteristics changing over time, with disruptions to physical/biological components leading to shifts in population numbers
• Cellular respiration uses oxygen to release stored energy in plants and animals
• Predatory interactions reduce populations
• Mutually beneficial interactions can lead to organisms needing each other for survival
• Biodiversity is the variety of species in Earth's ecosystems
• An ecosystem's health is measured by the completeness/integrity of its biodiversity
• Changes in biodiversity affect human resources

Reproduction and Genetics

• Organisms reproduce sexually or asexually, transferring genetic information to offspring
• Animals exhibit characteristic behaviors to increase the odds of reproduction
• Plants reproduce in various ways, sometimes relying on animal behavior or specialized features
• Both genetic factors and local conditions affect plant growth
• Genes reside in the chromosomes of cells
• Chromosome pairs contain two variants of each distinct gene
• Each gene controls the production of proteins, influencing an individual's traits
• Mutations in genes can alter proteins, affecting an organism's structure, function, and traits
• Variations in inherited traits between parent and child arise from genetic differences from a subset of inherited chromosomes (genes)
• Each parent contributes half of the genes acquired randomly by offspring in sexually reproducing organisms
• Individuals have two alleles (matching genes), one from each parent
• Alleles can be identical or differ from each other
• Mutations can be beneficial, harmful, or neutral
• Artificial selection involves humans influencing traits through selective breeding

Fossils

• The fossil record documents life's existence, diversity, extinction, and change over Earth's history
• Anatomical similarities and differences among organisms and fossils help reconstruct evolutionary history
• Embryological development comparisons reveal relationships not evident in fully-formed anatomy

Natural Selection

• Natural selection favors certain traits and suppresses others
• Adaptation through natural selection is when species change over time in response to environmental changes
• Traits that support survival/reproduction in a new environment become more common and others less common
• Distribution of traits in a population changes

The Solar System

• Patterns in the motion of the sun, moon, and stars can be observed, predicted, and explained using models
• Earth and its solar system are part of the Milky Way galaxy
• The solar system consists of the sun, planets/moons, and asteroids held in orbit by the sun's gravity, including comets and meteors
• The solar system model explains eclipses of the sun and moon
• A solar eclipse happens when the moon passes between the Earth and sun
• A lunar eclipse happens when the moon is directly behind the Earth
• Earth's spin axis is fixed in direction but tilted relative to its orbit around the sun
• Seasons are caused by this tilt and the differential intensity of sunlight on different areas of Earth
• The solar system formed from a disk of dust and gas drawn together by gravity

Earth Processes

• The geologic time scale organizes Earth's history from rock strata
• Rock and fossil records provide relative dates
• Tectonic processes create new sea floor at ridges and destroy old sea floor at trenches
• Earth's systems interact on scales from microscopic to global, shaping Earth's history and future
• Maps of ancient land and water patterns show how Earth's plates have moved, collided, and spread apart (divergent, convergent, transform plate boundaries)
• Water's movements cause weathering and erosion, changing land features and creating underground formations
• Earth processes result from energy flow and matter cycling
• Energy is derived from the sun and Earth's hot interior

Earth's Structure

• Layers of the Earth: Crust, Mantle, Lithosphere, Astenosphere, Core

Earth's Systems

• Energy flow and matter cycling produce chemical and physical changes in Earth's materials and living organisms
• Water cycles among land, ocean, and atmosphere via transpiration, evaporation, condensation, crystallization, and precipitation, propelled by the sun/gravity
• Humans depend on Earth's land, ocean, atmosphere, and biosphere for resources
• Minerals and fresh water are limited and unevenly distributed
• Local weather patterns are determined by complex water changes in the atmosphere
• Global ocean currents driven by temperature and salinity variations
• Weather and climate are influenced by interactions with the sun, ocean, atmosphere, ice, landforms, and living things, which vary with latitude, altitude, and local geography
• Weather can only be predicted
• The ocean influences weather and climate by absorbing and redistributing solar energy
• Human activities, such as greenhouse gas release, are a major factor in current global warming