study-notes

Science 8

So what’s the “space” between particles anyway?

---

Mix and Flow of Matter

• A fluid is a substance that has the ability to flow (liquid or gas). A non-fluid can behave like one when melted or dissolved into a fluid. They take up all available space in their container. (water, honey, air)
• There are three main types of matter, in order of density:
  1. Solids have particles tightly packed together and only vibrating in place. (tape dispenser, stapler, box)
  2. Liquids have particles with enough energy to slide past each other (fluid), yet still vibrate close to others. (water, honey, syrup)
  3. Gases have particles so far away from each other that they seem invisible due to the space between them. They move easily in all available directions. (oxygen, hydrogen, nitrogen)
• The Particle Model of Matter (PMOM) is always followed by all particles:
  1. All substances are made of tiny particles.
  2. All particles in a pure substance are the same.
  3. The particles have spaces between them.
  4. Particles are always in motion. The speed of the particles increases as temperature increases.
  5. Particles in a substance are attracted to each other. The strength of the attractive forces depends on the type of particle.
• Matter can also change form:
  • Solids melt or fuse into liquids, and sublimate into gases.
  • Liquids freeze or solidify into solids, and vaporize into gases.
  • Gases deposit into solids, and condensate into liquids.
  • Evaporation is a slower form of vaporization that allows for a wider range of temperature.
  • Water freezes at 0 degrees Celsius, and ice melts at 100 degrees Celsius.
• All matter can be classified as either a pure substance or mixture of substances.
  • Pure substances contain only one type of atom (element substance) or molecule (compound substance).
  • Mixtures have two or more solutions mixed together.
    • A homogeneous mixture has solutions evenly distributed and seems like one substance.
    • A heterogeneous mixture has solutions clearly separated.
      • When a heterogeneous mixture looks homogeneous, but settles over time, then it’s called suspension. (salad dressing, clay mixed in water)
      • The different parts/layers of a heterogeneous mixture are called phases.
      • Heterogeneous mixtures that don’t settle are called colloids.
        • Emulsions are colloids that require an emulsifying agent to stay combined. (mayonnaise)
      • A heterogeneous mixture that’s obviously visibly separated is called a mechanical mixture. (oil and water)
• A solute dissolves into a solvent to form a solution. (salt or sugar (solute) in water (solvent))
• Diffusion happens when a solute’s particles are more attracted to the solvent’s particles than itself, and particles always move.
  • The rate at which something dissolves can be increased through agitation (stirring/shaking), as it allows for the particles to be in contact with each other.
• Water is known as the universal solvent because it can dissolve many materials.
• To be soluble means to be able to dissolve in a particular solvent.
• When something is insoluble, it isn’t able to dissolve in a specific solvent.
• Solubility refers to the amount of solute that can be dissolved in a given solvent; this is usually measured in grams dissolved per 100 grams of water.
  • A saturated solution is a solution that can’t have any more solute dissolved in it.
  • An unsaturated solution is one that could have more solute dissolved.
  • Supersaturated solutions are solutions saturated past the limit. This is done through the use of cooling and crystals.
• WHMIS (Workplace Hazardous Materials Information System) safety symbols are used to convey the possible dangers associated with a product. (bleach, ammonia, strong acids)
• Sometimes fluids are used to help solids flow by mixing or dissolving them together, but the solid must then be retrieved later on.
• A method of separating some solid from a fluid could be dehydration, which is usually done via evaporation. (desalinating water, dehydrated foods)
• The act of taking the fluid from the mixture is called distillation. (getting pure water from saltwater)
• This can also be done for solids. (ore extraction)
• A liquid’s flow rate is how fast a fluid “runs”, or it’s resistance to flow. (juice flows faster than honey)
  • Temperature affects rate of flow because temperature is how active (moving) particles are. (hot is fast, cold is slow)
  • The flow rate of a gas acts in the opposite way; the hotter gas is, the more it collides with each other, and the slower it flows.
• Viscosity refers to the thickness or thinness of a fluid: the more viscous something is, the slower it flows. (syrup is viscous, water is less viscous)
  • Viscosity is important in many industries like paint, beauty, and food. (lipstick, nail polish, paint, mascara, dressing, and syrup)
  • The reason different fluids have different viscosities is because of internal friction (friction between particles inside the fluid itself).
• Mass is the amount of matter in a substance (grams), weight is the force of gravity exerted on an object (newtons (named after a smart guy (yay (nested parentheses)))), and volume is the amount of space occupied by something (liters or meters cubed).
  • On Earth, the force of gravity pulls down an object with 10 newtons for every kilogram. (10 KG is 100 N on Earth)
• Density is how “crowded” particles are in a solid, liquid, or gas.
  • Solids are generally denser than liquids, which are generally denser than gases.
  • The particle model of matter can tell us that the higher the density of something is, the smaller the space it takes up. (water compared to vapor)
  • Density can be calculated by looking at the mass-to-volume ratio of things (D = M/V). (the higher the mass or lower the volume, the higher the density)
  • A hydrometer measures liquid density by extending in different ways depending on how dense the liquid is.
• Buoyancy is the tendency for materials to rise or float in a fluid, while buoyant force is the upward force exerted on objects submerged in fluids.
  • An object is floating when it’s neither sinking nor floating and is in the same position.
  • Average density is the total mass of an object divided by the total volume. To be buoyant, the average density of the object must be lower than that of the fluid.
  • Most fish have what’s called a swim bladder. The amount of air in it changes to change the average density of the fish and its depth underwater.
  • Airships and hot air balloons float in the air because their average density is less than that of the surrounding air (hot air and helium is lighter than normal air).
  • The Greek scientist Archimedes made a discovery after being tasked by the ruler of Syracuse to find out if a crown he has is made of pure gold. He famously made the discovery after seeing water spill while in a public bath.
    • The Archimedes’s principle states that the buoyant force exerted upon an object is equal to the weight of the fluid displaced when the object is submerged.
• Pressure is a specific amount of force covered over a specific area. It’s measured in pascals (named after a smart guy).
• One pascal is equal to one newton per square meter, and therefore pressure can be calculated with the formula P = F/A.
  • Gases are said to be compressible, because their particles can be pushed somewhat closer together while remaining a gas.
  • Solids and liquids are said to be incompressible, because their particles can’t be pushed closer together while remaining a solid or liquid.
  • Compression is commonly used in some areas due to its useful property of being able to exert a force back. (car airbags, some running shoes, tires, grass in a field)
  • The Earth’s atmosphere exerts pressure too; it’s just that we’re really used to it. That’s why if you go really high up in a mountain or plane, you feel more sensitive to pressure change.
  • Pressure is commonly measured with a barometer, and they used to be made of mercury. A barometer uses gravity’s pressure over an area to push some mercury up a tube.
  • When air pressure is unequal inside and outside an enclosed space, the walls of that space may cave in or expand to compensate. (sucking on an empty juice box)
  • Particles flow from areas of high pressure to low pressure. (aerosol sprays)
  • Hydraulics is the study of pressure in liquids, and devices that utilize liquids to move something else using pressure are called hydraulic systems. They commonly use a series of tubes, hoses and pipes. (faucets, bike/car brakes, dentist equipment)
  • Pneumatic systems are similar, but use gases instead of liquids. They use gases instead mostly because gases are compressible, so they require compressors (devices that… compress air).

---

Light and Optics

• Light is a form of energy that you can see, and it radiates (spreads out) in all directions. This form of energy transfer involving radiant energy doesn’t require matter and is known as radiation. There are two main types of light:
  • A natural light source is from nature and isn’t made by humans. (stars, fires, fireflies)
  • An artificial light source isn’t from nature and is made by humans. (light bulbs)
• When light is absorbed by a surface, it can be transformed into several different forms of energy: thermal energy, electrical energy, or chemical energy. (solar cells, photosynthesis, sweater)
• There are also different sources of light:
  • Incandescent light sources heat an object to such a high temperature that it emits visible light. The emission of visible light by a hot object is called incandescence. (incandescent light bulb filament, candle flames)
  • Fluorescent light sources absorb emit visible light after absorbing high-energy, invisible ultraviolet light. In fluorescent tubs, mercury particles absorb electrical energy to emit ultraviolet light; they’re more expensive and toxic than incandescent light bulbs, but are more efficient because they don’t emit as much heat.
  • Phosphorescent light sources are similar to fluorescent light sources, but they are different in that they hold absorbed light for longer. (glow in the dark stuff)
  • Chemiluminescent light sources emit light following a chemical reaction producing energetic particles. (glow sticks)
  • Bioluminescent light sources are produced inside of living organisms. (fungi, fireflies, angler fish)
• Luminous objects, such as the Sun, emit light, while non-luminous objects, such as the Moon, reflect light but don’t emit any light of their own.
• The cost of lighting can be calculated by considering how many watts are required per hour. (a sixty watt bulb turned on for ten hours if it requires eight cents per kilowatt-hour requires 4.8 cents)
• The ray model of light tells us why things like shadows exist: light travels in rays, or straight lines, so shadows form where a ray of light’s path is obstructed by an object.
  • The closer an object is to a light source and further away from a surface, the larger its shadow is, and the further away an object is to a light source and closer to a surface, the smaller its shadow is.
• Different surfaces also react differently depending on their properties:
  • Transparent surfaces are see-through and allow for light to pass through. (glass, plastic water bottle)
  • Translucent surfaces allow some bent light through. (frosted glass, blinds, thin paper)
  • Opaque surfaces allow no light through and cast shadows. (concrete, a book, the stupid little laptop I’m using to write this stuff)
• Reflection is the process in which light strikes and bounces off of a surface. The smoothness of the surface also determines how clearly light is reflected.
  • The incident ray comes from a light source and hits the surface. The ray that bounces off of the surface from the incident ray is called the reflected ray.
  • The normal line is the line perpendicular to the point of reflection. The angle of reflection and angle of incidence both measure the angles of the incident and reflected rays.
  • The law of reflection states that the angle of reflection is equal to the angle of incidence. (45-degree angle of incidence will result in a 45-degree angle of reflection)
• There are three main types of mirrors that can reflect light:
  • A plane mirror is a flat surface and gives uniform results. (bathroom mirrors)
  • A concave mirror caves in and makes close objects large and farther objects upside-down. (makeup mirrors)
  • A convex mirror bulges outwards and reflects smaller images but has a wider field of view. (car mirrors on the sides)
• Refraction is the bending and slow-down of light as its rays travel to mediums of different densities. It can cause images to appear in a different position from where it really is.
  • When light travels into a denser medium, it will bend toward the normal, but will bend away when entering a less dense medium. The resulting angle is called the angle of refraction.
  • A mirage is the result of hot air near the ground refracting sunlight, making what appears to be a disappearing pool of water.
• A lens is a curved piece of transparent material, such as glass or plastic, that causes light to refract and bend.
  • A double concave lens is thinner and flatter in the middle than around the edges. Light that passes through will diverge and spread outwards.
  • A double convex lens is thicker in the middle than around the edges. Light that passes through will converge and come together. Sometimes, convex lenses form an upside down image.
  • The lens in the human eye is a convex lens, so that it can take in light rays, refract them, and focus them at the back of the eye.
    • Near-sightedness requires concave lens glasses to bring the image further away and to the back.
    • Far-sightedness requires convex lens glasses to bring the image closer away and to the back.
• The camera and the human eye are very similar in their workings (note that digital cameras are quite different from film cameras).
  • The lens of a camera moves around to keep the image in focus. The human eye’s ciliary muscles change the shape of the lens (protected by the cornea) to focus. This process is called accommodation. The ability to focus worsens as people get older.
    • The near point is the shortest distance at which an object is in focus (about 25 cm for the average adult), and the far point is the longest distance (technically infinity).
  • A camera’s diaphragm adjusts the aperture (opening) and allows variable amounts of light in, and the shutter limits the passage of light for different times. An eye’s iris changes the size of the pupil (opening) to allow for varying amounts of light in. This is called the iris reflex. (dark place, big pupil; bright place, small pupil)
  • At the back of the camera, light rays are focused onto a light-sensitive film; it uses chemical changes to record the image. Upon receiving light, the retina in the human eye produces electrical impulses that travel to the brain via the optic nerve.
    • The blind spot is the area in the retina that can’t detect light as that is where the optic nerve connects.
  • The parts of a camera are contained in a rigid, lightproof box. In the eyes, fluids called humors: the vitreous humor is between the retina and lens, while the aqueous humor is between the cornea and lens.
• Telescopes help us see distant objects more clearly. A refracting telescope has an objective lens to focus and collect light and an eyepiece lens to enlarge the image. A reflecting telescope uses a concave mirror to collect light rays, while the primary or objective mirror forms a real image that is then magnified by the eyepiece lens.
• Telescopes are actually just two reflecting telescopes mounted side by side. They use prisms to server as plane mirrors and reflect light back and forth.
• English scientist Sir Isaac Newton conducted an experiment where he placed a prism so that a thin beam of white light could pass through it. He then saw bands of color emerge refracted at different angles. It produced a rainbow effect.
  • He then placed another prism so that the rainbow of light went through it, and white light emerged.
• White light is commonly a spectrum of red, orange, yellow, green, blue, indigo, and violet, like the rainbow.
  • For example, when white light passes through a blue bottle, the glass absorbs all the colors except for blue, leaving blue light to be reflected.
  • The three colors red, green, and blue are called the primary additive colors because mixing them in proper amounts results in white light. The three colors yellow, cyan, and magenta are called secondary colors as they are the result of mixing two primary colors.
    • Pixels on a screen are tiny dots of the three primary colors. Therefore, they can create pretty much any visible color by varying the intensities of each color.
• The retina of the human eye contains two types of cells that respond to light: rods, which detect light, and cones, which detect color.
  • Some people have color blindness because the cones in their eyes are unable to detect certain colors.
• The distance from crest to crest in a wave is called wavelength, while amplitude is the distance between a wave’s rest position and the height of its crest.
  • The frequency is the number of cycles completed by a vibrating object in a unit of time, usually measured in hertz (cycles per second). (twenty hertz is twenty times per second)
• Scientists have developed the wave model of light, which pictures light travelling as a wave; it doesn’t explain everything about light, but it explains some unpredictable behavior, like light curving around an opening.
  • It can for example explain sunsets: longer wavelengths like red and orange tend to pass around particles like dust and grit, while shorter wavelengths like blue and violet reflect and scatter off of them. At sunset, sunlight has to pass through more atmosphere and therefore has plenty of opportunity for blue and violet waves to be reflected away, compared to red and orange.
• Laser light (Light Amplification by the Stimulated Emission of Radiation) is different from other types of lights in that its wavelengths are coherent (of the same type), compared to something like an incandescent light bulb (different wavelengths, so incoherent). (CD readers, supermarket scanners, surgery scalpels, eye correction)
• Visible light is of the electromagnetic spectrum, but other types of waves are invisible. Wavelengths are usually measured in nanometers, which are 0.000,000,001 of a meter.
  • Microwave ovens use a specific frequency of microwave (a type of radio wave with a long wavelength and low frequency) to be absorbed by water particles in food to vibrate and heat it up. They are also used for telecommunications and radar.
    • Other types of radio waves are used for things like broadcast radio and television programs.
  • Infrared radiation is invisible, but you can sense it, as it’s heat radiation. (motion sensors, burglar alarms, heat lamps)
  • Ultraviolet radiation can damage the skin and cornea, so that’s why we wear sunscreen and sunglasses. The decreasing ozone layer absorbs lots of the sun’s UV radiation.
  • X-rays can penetrate through things like skin and muscle, but not through bone.
  • Gamma rays have a short wavelength and high frequency. They result from nuclear reactions and can kill cells, so doctors can destroy cancerous tumors in patients’ bodies using radiation therapy.

---

Mechanical Systems

• When force is exerted on a screwdriver or seesaw, they would exert a force on something else; both are examples of a lever. A lever consists of a fulcrum and two sides with two parts: the effort force and arm (where effort is applied) and the load and its arm (the mass of an object that’s moved or lifted by the lever’s force). There are three types of a lever:
  1. Class one levers have the fulcrum between the effort and load. They are used for either power or precision. (scissors, seesaws, rowboat oars, bending neck)
  2. A class two lever has the load between the effort and fulcrum. It exerts a greater force on the load than the effort force exerted on it. (wheelbarrows, calves)
  3. In a class three lever, the effort is exerted between the fulcrum and load. A greater force must be exerted to affect the load, but it can be done more quickly. (hockey sticks, biceps)
• An inclined plane is a ramp or slope that reduces the force needed to be exerted to lift something.
• In science, work (joules) is force (newtons) multiplied by distance (meters). (1.2 N of work on a brick for 6 m = 1.2(6) = 7.2 J)
  • The work done on a machine is called input work, and the work the machine does on the load is the output work. A machine’s input work is always larger than its output work, because machines can’t be completely efficient (heat energy as a side effect).
  • Machines make work easier by changing the size or direction of the force exerted on a machine, changing the distance as well.
• The mechanical advantage of a machine is the comparison of the force applied on a machine to the force produced by a machine, so the smaller the effort force compared to the load, the greater the mechanical advantage. It is calculated by dividing the load force by the effort force. (a lever requiring an effort of 500 N that outputs 2500 N has a mechanical advantage of five)
  • A machine can also have a mechanical advantage less than one. (exerting a force of 736 N onto it as it outputs 81 N has a mechanical advantage of 0.11)
  • Mechanical advantage can also be calculated by dividing the length of the effort arm by the length of the load arm.
  • Class three levers have a mechanical advantage lower than one but instead offers a speed advantage.
• Ergonomics is the science of designing machines to suit people efficiently, comfortably, and safely. Factors such as weight, height, size, age, and sometimes gender have to be taken into consideration.
• A wheel and axle is a combination of two turning objects attached to each other at their centers.
  • For example, a winch consists of a small cylinder with a crank or handle. The axle of the winch acts like a fulcrum.
  • A gear is a rotating wheel-like object with teeth around its rim. A group of two or more gears is called a gear train. The driving gear turns the follower gear in the opposite direction.
    • A gear can turn another without contact by using a chain called a sprocket. The gears will then turn in the same direction.
    • The speed ratio of a pair of gears is the number of relationship of the number of gears of both gears. (a ten tooth gear moving at one rotation per second would turn a five tooth gear at two rotations per second)
• A pulley is a grooved wheel with a rope or chain running along the groove; the axle of the pulley acts like a fulcrum. A fixed pulley is attached to something and doesn’t work, while a movable pulley is attached to something else, often by a rope that goes around the pulley itself. The load may be attached to the center of the pulley.
  • A black and tackle is a complex combination of fixed and movable pulleys.
• Work is the transfer of energy, and the energy simple machines use is called kinetic energy, while potential energy is energy stored for later.
• The efficiency of a machine dictates how much of the energy given will be transferred to the load. It can be calculated by dividing the work done on the load by the work done by the effort, optionally converted into a percentage. Efficiency can be increased by removing friction (a lubricant like oil or grease).
  • However, sometimes friction is useful: tires need to stick to roads, shoes should stick to grass, and the hands of gymnasts should stick to bars.
• Pascal’s law states that pressure (pascals) exerted on a contained fluid is transmitted undiminished in all directions throughout the fluid and perpendicular to the walls of the container. (a water balloon being squished)
  • Many mechanical systems use this law; a hydraulic lift is a mechanical system that raises heavy objects using a fluid under pressure in a closed system. (the human body’s circulatory system, a service station lift for vehicles, a powerlift, bulldozer, tractor)
    • A hydraulic lift consists of a small cylinder and a large cylinder, and both of them are connected by a pipe and filled with oil. Water isn’t used because it’s a bad lubricant and can rust systems. There are pistons resting on the surfaces of the oil in the cylinders.
    • Because of Pascal’s law, force exerted on a small hydraulic piston will be multiplied onto its larger piston.
  • Pneumatic systems, on the other hand, use air or another gas and are open systems. (jackhammer, nail/staple gun, sandblaster, limb cast, hovercraft, the human body’s respiratory system)
  • Valves and pumps can be used to restrict or allow the flow of a fluid.
• Most modern, “complex” machines are actually just combinations of many simple machines, called subsystems. (car brakes, stuff in car hood, backhoe/excavator)
  • Rube Goldberg machines were humorous combinations of many machines together to accomplish a small, simple goal.
• In a steam engine, fuel such as coal or wood is burned to heat water in a boiler outside the engine. The water changes to steam and drives the engine. This invention led to many changes in transportation technology and also in the way that we manufacture goods.
  • A piston is attached to a steam engine to allow for rotation and movement, and an exhaust valve allows for old, cooled steam to escape.e
  • Steam engines were used (but not much anymore) in a variety of use cases: from locomotives to steamships.
• The internal combustion engine had the burning of fuel occur inside the engine itself, without an external furnace or boiler. Multiple cylinders and pistons moved either up and down or back and forth; a crankshaft changed this rotary moment.
  • The internal combustion engine was a much better candidate for aircraft than a steam engine, as it was lighter and smaller.
• The primary way of acquiring water changed a lot over time: water screws, wells, pumps, and then finally faucets.
• Over time, machines changed for the betterment (or deterioration) of human life. Machines became more efficient, safe, affordable, and comfortable. For example, all vehicles use lead-free gasoline to protect the environment.
  • During the industrial revolution, many new machines were made and improved upon; they paved the path for future mass production.
  • Back then, it was thought that fuel was unlimited and that the atmosphere could absorb all its pollutants, but when scientists disproved this, cars became more aerodynamic and efficient.
  • In the future, there will be many more new methods of doing things too.
• Scientists also have to make decisions that will impact society, like whether nuclear power plants should be made and used (they’re clean and efficient, but accidents could be devastating). Trade-offs and compromises have to considered.
  • Systems also have to be tested for factors such as comfort, safety, production, and efficiency. (crash-test dummies)

---

Cells and Systems

• Living organisms have signs of life: the requirement of energy, stimuli, reproduction, growth, and waste production.
• There are different levels of the organization of life. From smallest to biggest:
  1. Cells: all life is made of this.
  2. Tissue: different types make up different organs.
  3. Organs: serve different purposes
  4. Organ systems: multiple organs that perform a related task together.
  5. Organisms: multiple organ systems working in conjunction.
• Microscopes are required to observe things too small for the naked eye to see.
  • The Dutch merchant Anton van Leeuwenhoek and the English scientist Robert Hooke both experimented with early models of the microscope that used lenses.
  • Leeuwenhoek called cells animalcules, while Hooke called them cellulae (small rooms in Latin).
  • German botanist Matthias Schleiden, zoologist Theodore Schwa nu, and German scientist Rudolf Virchow said that all living things are made of one or more cells, and cells are the basic units of structure and function in all organisms.
  • Today, microscopes have improved significantly. Electron microscopes bounce electrons off of surfaces to magnify images much more than light microscopes (2,000,000 times more for example).
  • Compound light microscopes use multiple lenses to magnify much more. They consist of a tube, a stage, an arm, a diaphragm, a light source, a coarse-adjustment knob, a fine-adjustment knob, a revolving nosepiece, an eyepiece (or ocular lens), a condenser lens, and objective lenses.
    • The magnification of a microscope is controlled by the selected objective lens. The total magnification is measured by multiplying all the lenses magnifications.
  • The field of view of a microscope is how wide the view is. (smaller FOV means higher magnification)
• Unicellular organisms are made up of one cell, while multicellular organisms are made of many.
• Different organelles make up a cell, which are like organs, but small enough for cells.
  • The cell membrane surrounds and protects the contents of the cell and controls what goes in and out.
  • The cytoplasm is like a jelly that holds all the organelles inside the cell.
  • The nucleus controls the activities of the cell. It also contains the genetic material of the cell.
  • The vacuole is a space for extra food, waste, and other substances that can’t be immediately used.
  • The cell wall surrounds the cell membrane and protects the cell with its tough, rigid surface.
  • The chloroplast is where the process of photosynthesis occurs. Energy from the Sun is used to create carbohydrates.
  • The mitochondrion produces energy for the cell using tiny food particles.
  • The ribosome make proteins.
  • The rough endoplasmic reticulum serves as a base for ribosomes.
  • The smooth endoplasmic reticulum produces fats.
  • The Golgi apparatus processes proteins.
  • There are two types of cells: animal cells and plant cells. They both have different organelles.
    • Animal cells have all the organelles except for the chloroplast and cell wall, and they have multiple small vacuoles.
    • Plant cells have all the organelles, and they have one big vacuole.
• Cells are very small[citation needed]; they usually have a diameter that measures from ten to fifty micrometers.
• Permeability is the property or condition of being able to allow a fluid through a material.
  • If something is permeable, it allows particles through. (a shirt is permeable to water)
  • If something is semi-permeable (or selectively permeable), it allows some particles through. (a cell membrane)
  • If something is impermeable, it allows no particles through. (plastic is impermeable to water)
• Diffusion is when solute spreads from high to low concentrations in a solvent, until equilibrium is reached. (a fart spreading throughout a class)
• Osmosis is diffusion but across a membrane. This time, the amount of solvent that moved to the other side is measured. (plant roots absorbing water)
• These two processes are done in cells with foreign particles outside of it.
• There are also terms for the balance of solute and solvent between a permeable membrane:
  • An isotonic solution has an equal balance of solute between a membrane in a solvent.
  • A hypotonic solution has a greater balance of solute between a membrane in a solvent.
  • A hypertonic solution has a lesser balance of solute between a membrane in a solvent.
• Plants have vascular tissues to connect the roots and leaves. These are needed for creating sugars from water through photosynthesis.
  • The xylem brings water and nutrients from the roots to the leaves.
  • The phloem brings sugars (food) to the rest of the plant
• The roots of a plant are covered in small, thin hairs called root hairs. They increase the surface area of the roots to allow for more water and nutrient absorption.
• There are also stomata on the undersides of leaves. They allow for air to enter the leaves, and allow for water to leave the plant through transpiration.
  • Trans-pirate Transpiration is the loss of water in a plant through evaporation.
• All cells are specialized and have their own purpose and task to do. This also results in different shapes. (heart cell, nerve cell, blood cell, skin cell)
• Multicellular organisms have several advantages over unicellular organisms: they can grow larger, live in a variety of environments, obtain energy from a variety of sources, and have cell organization.
• Tissues are groups of similar cells to serve a special purpose. (muscle tissue, nerve tissue, epithelial (skin) tissue, connective (bone) tissue)
• Organs are distinct structures of the body that perform particular functions. They’re made of several types of tissues working together. (eyes, brain, stomach, heart, lungs, intestines, skin)
• Organ systems are groups of organs that perform activities to help the organism as a whole. (plants root system, plant shoot system, human digestive system, human circulatory system)
• The human body has three types of blood vessels, from first to last:
  1. Arteries leave the heart and carry blood with them. They have thick, muscular walls
  2. Capillaries allow for the exchange of oxygen with blood. They’re very thin (about a cell thick).
  3. Veins carry blood back to the heart and have valves to prevent backflow. They have thin walls.
• There are also different parts of blood: plasma is the liquid part, red blood cells carry oxygen, white blood cells defend against diseases, and platelets help stop bleeding.
• The circulatory system consists of the heart (which consists of four “chambers”) and all the blood vessels associated with it.
• Here’s the process of some air going through the human respiratory system, in order:
  1. The diaphragm moves the lungs to inhale.
  2. The air comes in through the nose or mouth.
  3. It goes down the trachea and enters the lungs.
  4. It then divides into the left and right bronchi.
  5. Each bronchus then splits into thousands of bronchioles.
  6. These in turn separate into millions of air sacs called alveoli.
  7. The capillaries inside the alveoli take the oxygen from the air and infuse it with the body’s blood.
  8. The diaphragm moves the lungs to exhale.
• Here’s the process of some food going through the human digestive system, in order:
  1. The food enters through the mouth and gets chewed on to increase surface area.
  2. Saliva assists with a form of chemical digestion.
  3. The food goes down the esophagus through the process of peristalsis (contracting muscles).
  4. The food enters the stomach and is digested through chemical (acid) and mechanical (churning) digestion.
  5. In the small intestine, the nutrients of the food are absorbed. The small intestine is also lined with villi.
  6. There are many villi to increase surface area, and they contain a network of capillaries for bringing food particles/nutrients into the bloodstream.
  7. The large intestine’s purpose is to re-absorb the food’s water and move waste out of the system.
  8. The food comes out of the system as poop feces.
• The nervous system consists of the brain, spinal cord, and branches of nerves and neurons covering the whole body.
• The excretory system eliminates waste products from the blood using the kidney by producing pee urine.
• There are also organs called the accessory organs (even though they’re very important):
  • The liver regulates many chemical levels in the blood and excretes a product called bile that carries away waste.
  • The gallbladder holds bile before it’s released into the small intestine.
  • The pancreas contains glands that create substances that help with digestion and control blood sugar (insulin).
• Circulatory system disorders are the leading cause of death, and one of the most common is high blood pressure (hypertension). It can lead to heart attacks and strokes.
• Smoking causes many problems: nicotine constricts blood vessels, and carbon monoxide competes with oxygen in the lungs.
• High salt diets can raise blood pressure, straining the heart, and high fat diets clog arteries with cholesterol, leading to blood clots.
• Fat is different from carbohydrates in that it can be stored, but excess fat is bad.
• Proteins are essential for the growth and repair of body tissues.
• A low amount of fiber makes the colon spend more time processing waste materials; this can irritate the colon wall and cause colon cancer.
• Peptic ulcers are caused by long-term emotional stress, smoking, alcohol, and excess aspirin. They occur when a wall of the stomach or small intestine is damaged by extra stomach acid.
• The cilia in the respiratory system are hairlike projections that remove airborne particles. Smoke and pollutants irritate this lining, causing mucus. The lining will then be inflamed. This is called bronchitis.
• Smoking is the leading cause of lung cancer: it starts when certain compounds contact lung tissue, and cells grow out of control and kill healthy cells.

---

Fresh and Salt Water Systems

• More organisms inhabit water than other places on earth, and furthermore, all organisms require water to survive.
• 97% of Earth’s water is salt water, and the remaining is fresh water.
• We have many uses for water: survival, hygiene, agriculture, industry, and leisure.
• The water cycle is the constant movement of water throughout the planet:
  1. Water evaporates from bodies of water and into the air; this is driven by the Sun.
  2. The water vapor then condenses into clouds.
  3. The clouds then precipitate in the form of rain, snow, hail, etc.
  4. The water runs off of streams and collects somewhere, while carrying sediments.
• On average, there’s enough water vapor in the atmosphere for only a ten-day supply of precipitation worldwide, and about 78% of Earth’s precipitation falls into the oceans.
• Glaciers and ice sheets make up about 75% of the world’s fresh water, and groundwater makes up about 20% of that. This leaves 0.02% of the world’s water as fresh water available from rivers, lakes, ponds, etc.
• Water quantity refers to the amount of water there is available, and water quality refers to how suitable water is for a purpose.
• Frozen fresh water takes up about 10% of Earth’s surface area. It can exist in many forms:
  • When snow accumulates in great weights, it compresses bottom layers into ice. This also causes some melting. This moving mass of ice and snow is called a glacier.
  • An ice cap is a glacier that forms on an extensive area of relatively level land that flows outwards from the center, whereas an icefield is an upland area of ice that feeds two or more glaciers.
  • Snowflakes gradually become grains when enough pressure (about 30 meters of snow) is applied and water is given.
  • Valley glaciers are glaciers that form in mountain ranges.
  • Very thick glaciers that form near the poles and bury mountain ranges are called continental glaciers.
  • An icefall is the result of a glacier flowing over a steep cliff, and a crevasse is a fissure or crack in the ice of a glacier.
  • If a glacier melts faster than it accumulates ice, then it advances, otherwise it retreats.
  • Pack ice is a sheet of seawater ice under about 5 meters thick that breaks easily.
  • Icebergs are large chunks of ice that split or calve from continental glaciers as the flow down into the ocean.
  • A millwell is a rounded drain in ice chiseled by a stream.
  • Glaciers can be considered to be natural reservoirs; they store vast quantities of fresh water and release it when it’s most needed.
• A glacier can also change the surrounding landscape:
  • Glaciers also pick up and move sediments, as well as erode rocks. Water can seep in through cracks, freeze, and expand to break open rocks.
  • Marks known as striations appear when rock fragments scrape bedrock as they’re moved by glaciers.
  • Valley glaciers can cause erosion and form a bowl-shaped basin called a cirque in mountains.
  • When at least two glaciers erode a summit from multiple directions, a ridge called an arete or a sharpened peak called a horn is formed.
  • A mixture of varied sediments deposited by sediments is called a till, and the material left by a glacier’s meltwater is called outwash.
  • A big ridge of material left by a glacier is called a moraine, and an esker is the winding ridge of sand and gravel left by rivers underneath glaciers.
• Over the last several million years, Earth has had at least seven major periods of cooling called ice ages. The last one began 120,000 years ago and ended about 11,000 years ago.
• The world was very different during an ice age; glaciers covered as much as 28% of the land. North America then was very similar to Greenland today.
• There are multiple hypotheses as to what causes ice ages:
  • There might’ve been occasional reductions in thermal energy given off by the Sun.
  • Increased volcanic activity may add a lot of dust into the atmosphere.
  • Periods of mountain formation might’ve increased the area of high mountain ranges on Earth. The extra snow remaining on these cold peaks through the summer might’ve reflected sunlight to reduce the temperature.
  • The movement of Earth’s tectonic plates might’ve altered the shape of the oceans and the flow of their currents, possibly resulting in imbalance.
  • Changes in the tilt of the Earth’s axis or orbit around the Sun might’ve produced colder climates.
• The greenhouse effect is a natural warming caused by gases (mainly carbon dioxide) in the atmosphere trapping heat.
• In a pond, sunlight reaches all the way to the bottom and allows for plants to grow there, whereas with a lake, sunlight doesn’t reach the bottom and plants can’t grow there.
  • The depth to which sunlight will penetrate depends on water’s clarity: the amount of matter suspended in water.
• Wetlands are low areas in land that are saturated with water all or much of the time. Marshes are shallow (less than one meter) water wetlands.
• Streams and rivers are fast-flowing waterways, and different ones differ greatly in their speed, temperature, nature, oxygen content, and clarity.
• Cold water contains more oxygen than warm water.
• All water is always moving and is part of a watershed. A watershed, or drainage basin, is an area of land that drains into a body of water such as a river, pond, wetland, lake, or ocean.
  • When water comes down, it either filters into groundwater or runs downhill. Watersheds also vary in size and may have some nested inside each other.
  • In North America, a continuous ridge of mountain ranges divides the continent into two main drainage areas. One flows northeast to the Hudson Bay or to the Gulf of Mexico, and the other flows to the Pacific Ocean.
  • The upstream areas of a watershed are called headwaters, and the end point of the water flowing through a watershed is called the outflow (usually a river mouth).
  • People who manage water supply have to pay careful attention to factors such as watersheds, flooding, streams/rivers, soil, run-off, and vegetation.
  • Streamflow is the amount of water discharged by a watershed. It involves measuring the amount of water (volume) that flows past a certain point over a period of time (velocity).
• The amount of water, slope, and surface of the ground affects whether water runs off or soaks into the ground.
• As a stream or river flows downhill, it carries sediments and materials it eroded along with it. It then deposits it at the end and throughout.
• Sediment plays a major role in the transportation of pollutants. Toxic chemicals can attach themselves to sediment particles and will move with the water carrying the sediment.
  • Sediments can be studied by scientists to learn more about where sediment comes from and how it affects the area. (flow, pollutants, agriculture)
  • De-sedimentation can be done to prevent sediments from entering waterways. (dredging in rivers)
  • An eroded river can be restored by planting native vegetation along its banks to stabilize the soil (less erosion and deposition). Reinforced rock baskets called rip-rap and digger logs may be necessary too.
• Water underground trickles through cracks, pores, and crevices before hitting a layer of bedrock.
  • The sort of underground river system formed by permeable and impermeable rocks and holes filled with water is called an aquifer. The water down there moves, albeit very slowly.
    • The top of an aquifer is called a water table, and its location may vary.
  • Groundwater is essential to many things. (agriculture, water level, feeding in water)
    • Wells and depend on holes dug down to a point below the water table (to get water).
    • When groundwater naturally flows out onto the surface, a spring is formed.
  • Conserving aquifers from depletion is important as they’re needed for humans and wildlife.
• Water can be polluted from two sources:
  • Point sources are small, defined areas of pollutants. (gasoline leaks, accidental spills)
  • Non-point sources are wide areas of pollutants. (pesticide and fertilizer run-off)
• When a large amount of water overflows and spills out of a river’s banks, the flooded river valley is called a flood plain.
  • Dams can prevent this and do other things too. (generate electricity, store water, supply water)
• On average, 1000 grams of seawater contains 35 grams of dissolved salt (35 parts per thousand or PPT).
  • Salinity is the measure of the amount of salts dissolved in a liquid.
  • An ocean’s salts mostly came from rocks on lands, as their salts were carried over to the ocean.
  • Seawater salts can also come from volcano eruptions. (sulfur and chlorine)
  • Fresh water also has salts. It’s just that ocean water has 16,000 times as much.
• Light only penetrates through about 100 meters of the ocean, so most marine organisms are found in the top 180 meters.
• The terrain of the sea floor and ocean basin is somewhat similar to the terrain on land.
  • Long undersea mountain chains called ocean ridges run along the centers of the oceans and are formed by hardened volcanic rock.
  • Narrow, steep-sided canyons called trenches form where the edge of an ocean plate pushes against the edge of a continental plate; the ocean plate is then forced to bend steeply down beneath the heavier continental plate.
  • Between all that, the ocean floors are remarkably flat. They’re called the abyssal plains and are formed by thick deposits of sediment moved by landslides.
  • Instead of starting at coastlines, ocean basins are connected to continents by a submerged part called the continental shelf. This is then followed by the continental slope, which drops steeply downwards.
• Ocean waves are primarily caused by winds.
  • Smooth waves are called swells.
  • The tumble of water onshore after a wave collapses due to friction is called a breaker.
  • Waves can erode and shape shorelines through erosion and deposition. A longshore current is a long current… at the shore.
  • Waves control beaches in two ways:
    • Strong winds cause waves to erode the beach.
    • Slow, calm waves deposit sediment onto the beach.
• The daily rises and falls of the oceans caused by the positions of the Sun and Moon are called tides. The upper and lower edges of a beach are determined by the high-tide mark and the low-tide mark.
  • The largest tidal movements (called spring tides) occur when the Earth, Moon, and Sun are in a line. At these times, tides are extra high and extra low.
  • The smallest tidal movements (called neap tides) occur when the Sun and Moon are at a right angle to the Earth. On these days, there’s little difference in depth between high and low tides.
  • The difference in level between a high tide and a low tide is called the tidal range.
  • Tides are controlled by the Earth, Sun, and Moon due to their gravitational pull.
  • The rotation of the Earth shifts where the tides take place throughout the day.
• The broad, continuous movements of ocean water are called currents. They’re driven by winds, flow in one direction, and connect one place with another.
  • Winds travel in a clockwise direction in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. Ocean currents move in the same way.
  • Three things influence the direction of winds and surface currents: the uneven heating of the atmosphere, the rotation of the Earth, and the continents.
    • Winds begin as a result of the uneven heating and pressure of the air.
    • The Earth’s rotation bends the moving currents.
    • The moving currents are forced to turn when they meet the solid surface of the continents.
    • Currents carry warmth and cold around, due to their high heat capacity. For example:
      • The Gulf Stream carries warm water from the Caribbean Sea across the Atlantic Ocean.
      • The Labrador Current carries cold water from the Arctic Ocean down to the east coast of Canada.
• The diversity, or variety, of life varies from habitat to habitat.
• Many different animals have different adaptations to aid with surviving.
  • Some animals have gills to allow for breathing underwater, while others have lungs and come to the surface to breathe.
  • In places where water is constantly moving quickly, some aquatic animals need to avoid being swept away. Clams burrow down into the mud or sand, sea stars have special appendages, and snails have suction-cup-like feet.
  • Fish and whales have a streamlined shape (fins and tails) that allows for easier swimming through water.
  • Water striders can skate and jump on the surface film of water by using its buoyancy.
  • Some animals filter food out of water to eat.
• There are two types of the tiny floating animals known as plankton:
  • Phytoplankton are plant planktons that use photosynthesis.
  • Zooplankton are animal planktons that often have spines or other appendages to help with floating in water.
• Attached plants are plants attached to the bottom of a body of water. Seaweed for example has a structure called a holdfast.
  • Underwater plants also have stomata on the top of leaves and are generally more flexible than land plants.
• Nutrients such as nitrates and phosphates are required by plants to survive. They mostly come form land or detritus (decaying bodies of plants and animals).
  • Sometimes nutrients are very abundant (spring), and at other times, nutrients are scarce (late summer).
  • Nutrient pollution is the result of too many nutrients that usually originate from fertilizers or animal wastes. They can cause an increased growth of algae or another aquatic plant, called an algal bloom.
• Food chains are sequences of feeding relationships between organisms. They form the basis of food webs (overlapping food chains). (phytoplankton -> zooplankton -> herring -> seal -> toothed whale)
  • Some animals are important links, like small fish, as they and their eggs are important to many animals.
  • Fisheries can significantly affect the populations of fish, because they tend to target larger fish with higher market prices. This leaves a boost in the population of smaller fish.
  • Pollution also affects animals. When the concentration of a toxin is magnified through a food chain (phytoplankton absorbs toxin, zooplankton eats thousands of phytoplankton, fish eats hundreds of zooplankton, bird eats many fish), it’s called biomagnification. So animals high up in the food chain are most severely affected.
• Some plants and animals don’t use the Sun’s energy, but rather sea-floor vents at the bottom for energy. The process of using its chemicals for food is called chemosynthesis.
• In order for water to be safe to drink (potable), it has to cleaned and tested. Dissolved solids, salts, and organisms have to be removed.
  • Hard water contains lots of dissolved calcium and magnesium, while soft water has less.
• Acid precipitation is caused by dissolved sulfur dioxide and nitrogen oxide in the atmosphere. These are waste gases released by coal-burning industries, metal smelters, and automobiles.
  • They combine with water vapor in the atmosphere to form sulfuric and nitric acids. The then return in precipitation that can be more acidic than vinegar.
    • This acid rain can damage and kill off plants and animals, and it can dissolve heavy metals into the soil.
• The pH scale is used to determine whether a substance is a base or acid. It measures from 1 (very acidic) to 14 (very basic), with 7 being normal.
• A bioindicator species is a species of organism that reacts in a very sensitive way to changes in their environment. They’re studied by scientists to know when things change. (stonefly larvae, mayfly larvae, caddisfly larvae, snails, leeches, crayfish, segmented worms, midgefly larvae)
• Water management involves carefully balancing an area’s available water for people, industries, wildlife, and the environment. Pollution must also be taken into consideration.
• For water to be potable (safe to drink), it must be purified, so many communities clean water through the process of water treatment:
  1. Water from a source moves through an intake pipe. A screen keeps out debris and fish.
  2. Pumps move water to the treatment plant.
  3. Chemicals are added, and they stick to suspended materials and most bacteria.
  4. The suspended solids settle to the bottom of a huge tank.
  5. The water is pumped through filter beds of sand and gravel. These trap smaller particles of suspended materials, leaving clear and drinkable water.
  6. Chlorine or ozone may be added to kill remaining germs. Fluoride is added in many places for tooth protection.
  7. The clean, safe drinking water is delivered through underground pipes to homes and businesses.
• The solid and liquid waste from homes, businesses, and industries is called sewage. In urban areas, it goes to sewage treatment plants, while in rural areas, it goes to septic tanks that are regularly cleaned out.
  • Treated wastewater, called effluent, goes back into rivers, lakes, groundwater, and the sea. It can also be used to irrigate crops.
• In some places were shortages of fresh water are common, costly desalination plants are required to desalinate water.
  • While distillation can also be used, reverse osmosis is when pressure is exerted to force osmosis.

This site is open source. Improve this page.