Human Body Systems

• Science is a systematic study of the natural world through observation and experimentation, leading to testable explanations and predictions.
• Biology is the study of living organisms, including their structure, function, growth, origin, evolution, and distribution.
• Chemistry is the study of matter and its properties as well as how matter changes.
• Earth Science is the study of Earth's structure, properties, processes, and four and a half billion year history. It includes the study of the planet's solid earth, oceans, atmosphere, and its environment.
• Physics is the study of matter, energy, and the fundamental forces that govern the universe.

Human Systems

• Human systems encompass various organ systems working together to maintain life.
• The skeletal system provides structure and support.
• The muscular system enables movement.
• The nervous system facilitates communication and control.
• The circulatory system transports blood, oxygen, and nutrients.
• The respiratory system enables gas exchange (oxygen and carbon dioxide).
• The digestive system breaks down food for energy and nutrients.
• The excretory system removes waste.
• The endocrine system regulates hormones.
• The immune system defends against disease.

Mixtures

• A mixture is a combination of two or more substances that are physically combined but not chemically bonded.
• Each substance in a mixture retains its individual properties.
• Mixtures can be separated by physical means.

Solutions

• A solution is a homogeneous mixture where one substance (solute) is dissolved evenly into another (solvent).
• Solutions are transparent and do not scatter light.
• The solute particles are very small, typically at the molecular or ionic level.
• Examples include saltwater (salt dissolved in water) and sugar dissolved in water.

Suspensions

• A suspension is a heterogeneous mixture in which solid particles are dispersed in a liquid but are large enough to settle out over time.
• Suspensions are cloudy or opaque and scatter light.
• The particles are larger than those in a solution and are visible to the naked eye or under a microscope.
• Examples include muddy water and dust in air.

Colloids

• A colloid is a mixture with properties between those of a solution and a suspension.
• Colloid particles are larger than those in a solution but smaller than those in a suspension.
• Colloids exhibit the Tyndall effect, scattering light and appearing translucent or opaque.
• Particles do not settle out due to Brownian motion.
• Examples include milk, fog, and gelatin.

Properties of Materials

• Physical properties are characteristics that can be observed or measured without changing the substance's chemical identity.
• Physical properties include color, density, hardness, melting point, boiling point, and conductivity.
• Chemical properties describe how a substance interacts with other substances or changes into new substances.
• Chemical properties include flammability, reactivity, and oxidation.
• Density is mass per unit volume (ρ = m/V).
• Hardness is resistance to scratching or indentation.
• Conductivity is the ability to conduct electricity or heat.
• Malleability is the ability to be hammered into thin sheets.
• Ductility is the ability to be drawn into wires.

Light

• Light is a form of electromagnetic radiation that is visible to the human eye.
• Light exhibits properties of both waves and particles (wave-particle duality).
• The electromagnetic spectrum includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
• Visible light spans wavelengths from approximately 400 nm (violet) to 700 nm (red).
• Light travels in straight lines and can be reflected, refracted, and absorbed.
• Reflection is the bouncing of light off a surface.
• Refraction is the bending of light as it passes from one medium to another.
• Absorption is the process by which light energy is taken up by a substance.
• Lenses use refraction to focus or disperse light.
• Prisms use refraction to separate white light into its component colors (spectrum).

Sound

• Sound is a mechanical wave that travels through a medium (solid, liquid, or gas).
• Sound is produced by vibrations.
• Sound waves are longitudinal waves, meaning the particles of the medium vibrate parallel to the direction of wave propagation.
• Speed of sound depends on the medium's properties (temperature, density).
• Sound travels faster in solids than in liquids or gases.
• Frequency is the number of wave cycles per second, measured in Hertz (Hz), and determines pitch.
• Amplitude is the maximum displacement of particles in a wave and determines loudness.
• The human ear detects sound waves, converting them into electrical signals that the brain interprets.
• Sound can be reflected (echoes), refracted, and absorbed.
• Sound can experience constructive and destructive interference.

Environment

• The environment includes all living and non-living things that surround and affect an organism.
• Ecosystems are communities of interacting organisms and their physical environment.
• Biomes are large geographic areas characterized by specific climate conditions, animal populations, and plant species.
• Key environmental factors include temperature, precipitation, sunlight, and nutrient availability.
• Pollution is the contamination of the environment with harmful substances.
• Air pollution includes smog, acid rain, and greenhouse gases.
• Water pollution includes sewage, industrial waste, and agricultural runoff.
• Soil pollution includes pesticides, heavy metals, and plastic waste.
• Conservation is the protection, preservation, and management of natural resources.
• Sustainability is meeting the needs of the present without compromising the ability of future generations to meet their own needs.

Soil

• Soil is the outermost layer of the Earth's crust, composed of mineral particles, organic matter, water, and air.
• Soil formation is influenced by parent material, climate, topography, organisms, and time.
• Parent material is the underlying rock from which soil is derived.
• Climate affects the rate of weathering and decomposition.
• Topography influences drainage and erosion.
• Organisms contribute to the breakdown and mixing of organic matter.
• Time allows for the accumulation of soil horizons (layers).
• Soil horizons include:
  • O horizon (organic matter)
  • A horizon (topsoil, rich in humus)
  • B horizon (subsoil, accumulation of minerals)
  • C horizon (weathered parent material)
  • R horizon (bedrock)
• Soil properties include texture, structure, porosity, and pH.
• Soil texture refers to the proportion of sand, silt, and clay particles.
• Soil structure is the arrangement of soil particles into aggregates.
• Soil porosity is the amount of pore space in the soil.
• Soil pH measures the acidity or alkalinity of the soil.
• Soil is essential for plant growth, providing support, water, nutrients, and air.
• Soil erosion is the removal of topsoil by wind or water.
• Soil conservation practices include terracing, contour plowing, and crop rotation.