Experimental Variables & Scientific Method

• Identifying experimental variables is a relevant science skill.
• Experiments include identifying independent, dependent, and controlled (constant) variables.
• The independent variable is the one deliberately changed by the experimenter.
• Independent variables are conventionally on a results table's left-hand side and the horizontal (x) axis.
• The dependent variable changes due to the independent variable.
• Dependent variables are measured and conventionally put on a results table's right-hand side and the vertical (y) axis.
• Controlled or constant variables can change but are deliberately kept the same for a fair experiment.
• The experimental control is the sample to which all other samples are compared when there is a change in the independent variable.
• Writing an aim, hypothesis, and conclusion is an important science skill.
• An aim states what the experiment is meant to achieve and uses phrases like "To investigate..."
• A hypothesis indicates what you expect to happen in the experiment and why.
• Validity refers to the soundness and legitimacy of an investigation
• Key questions during a first-hand investigation include:
  • Did the experiment achieve its aim?
  • Were all relevant variables kept constant?
  • Was appropriate equipment used to reduce experimental error?
  • Was there a suitable range to observe a trend?
• Reliability is ensured with repetition and replication using a large sample size under identical conditions.
• Accuracy is ensured by using measuring devices had sufficient graduations and using recently calibrated equipment.
• Constructing tables to summarize data and calculate averages is a relevant science skill.
• Interpreting column graphs, histograms, bar graphs, line graphs, and pie graphs is a relevant science skill.
• Hand drawing graphs is a relevant science skill.

Heat Transfer

• Heat transfers through solids, liquids, and gases via:
  • Conduction (through solids): Particles pass energy by bumping.
  • Convection (through liquids and gases): Warm areas rise, cool areas sink, creating a current.
  • Radiation (through empty space): Via infrared waves, no particles needed.
• Conduction involves tightly packed particles in solids vibrating more when heated, transferring energy through collisions.
• Convection in liquids and gases involves heated particles moving faster, becoming less dense, and rising.
• A convection current is formed, transferring heat through the fluid.
• Touching a metal spoon in hot tea transfers heat because metal is a good conductor with tightly packed particles.

Waves

• A wave transfers energy but not matter and is a disturbance in space.
• Wavelength is the distance between two matching points on a wave.
• Frequency is the number of waves passing a point per second, measured in Hertz (Hz).
• Speed is how fast the wave travels, measured in meters per second (m/s).
• Amplitude measures the height of the wave from the middle line to the crest or trough, indicating the wave's energy.
• Perform simple calculations using the equation v = fλ.
• Transverse waves feature particles moving perpendicular to the wave direction.
• Compression/longitudinal waves feature particles moving parallel to the wave direction.
• Transverse waves look like up and down ripples, while compression/longitudinal waves look like areas of compression and rarefaction.

Slinky Spring Waves

• A transverse wave is modeled by laying a slinky flat and moving one end side to side.
• A compression/longitudinal wave is modeled by pushing and pulling one end of the slinky back and forth.
• Sound is a compression (longitudinal) wave that travels through air by compressing and stretching particles.
• Compressions and rarefactions are created, making sound not visible but audible or felt.
• Pitch depends on the frequency which is how many waves pass a point per second (measured in Hertz, Hz).
  • High frequency means a short wavelength and high-pitched sound, like a piccolo.
  • Low frequency means a long wavelength and low-pitched sound, like a bass guitar.
• Loudness depends on the amplitude which is how big the wave is from the rest position to the crest/trough.
  • Big amplitude means more energy and a louder sound.
  • Small amplitude means less energy and a softer sound.

Musical Instruments

• A short string vibrates faster, creating a higher frequency, shorter wavelength, and higher pitch.
• Amplitude: blowing harder or striking harder makes a louder sound.
• Shorter air column means the air vibrates faster and the product is a higher frequency producing a higher-pitched sound.
• Longer air column vibrates slower, creating a lower frequency and pitch.
• Sound travels fastest in solids, then liquids, then gases due to particle arrangement.
• Solids have particles very close together, liquids are close but not tightly packed, and gases are spread out and move freely.

Light

• The electromagnetic (EM) spectrum is a range of waves.
• The range of waves includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays which do not require medium.
• All EM waves travel at 300,000,000 m/s (3 × 108 m/s) in a vacuum.
• EM waves are transverse waves with vibrations at right angles (90°) to the direction of wave movement.
• EM waves have electric and magnetic fields at right angles to each other and the wave's direction.
• Radio waves have the longest wavelength, lowest frequency, and least energy.
• Gamma rays have the shortest wavelength, highest frequency, and most energy.
• Shorter wavelength will produce higher frequency meaning more energy and longer wavelength will produce lower frequency meaning less energy.

Reflection

• The angle of incidence equals the angle of reflection on smooth surfaces leading to even reflection.
• A plane mirror reflects light and creates an upright, same-size image.
• A concave mirror converges light rays, and can make real or virtual images and magnifies upright
• A convex mirror always make virtual, upright, smaller images.
• A lens refracts light and focuses it to form images in the eye and in devices.

Refraction

• If light enters a denser medium, it slows down and bends towards the normal.
• If light enters a less dense medium, it speeds up and bends away from the normal.
• The refractive index measures how easily light travels through a substance.
• Smaller refractive index results in faster light travel.
• Reflection is when light bounces off a surface.
• Refraction is when light bends (refracts) as it moves through different materials.
• Absorption occurs when light or energy is taken in by a material and not reflected or transmitted.
• Dark colors feel hotter as they absorb more light energy.
• Total internal reflection happens when light travels from a more dense to a less dense material and the angle of incidence is greater than the critical angle.

Total Internal Reflection

• Total internal reflection includes optical fibres, prisms in binoculars, and diamond sparkles.
• Optical fibres: Light signals bounce along the inside of the fibre without escaping.
• Prisms in binoculars: Reflect light inside to keep the image bright.
• Diamond sparkle: Light gets trapped and bounces inside the diamond, making it shine brightly.

Multicellular Coordination

• Unicellular organisms are composed of one cell and do all cell jobs while multicellular organisms have many cells that are more specialized.

Body Systems Working Together

• Digestion breaks down food into nutrients.
• Respiration brings in oxygen for cells and removes carbon dioxide.
• Circulation transports oxygen and nutrients to cells and carries aways carbon dioxide and the waste.
• Skeletal system protects organs (e.g. lungs, heart) and makes red blood cells that carry oxygen
• Muscular system the heart muscle pumps blood and digestive muscles move food for.
• Nervous controls and coordinates all nervous system which tells the body when to eat, breathe, pump faster, etc.

Body Systems Overview

• The digestive system breaks down food, allowing glucose and nutrients to enter the blood.
• The respiratory system brings oxygen into the body.
• The circulatory system delivers glucose and oxygen to cells.
• Cells use glucose and oxygen to make energy, generating waste (CO2, and urea).
• The circulatory system transports CO2 to the lungs and waste to the kidneys.
• The respiratory system then removes CO2 when you breathe out.
• The nervous system controls the speed of these processes.
• The muscular and skeletal systems support movement and protection of vital organs.

Nervous vs Endocrine System

• Both coordinate body systems and maintain homeostasis.
• Both can shut off when no longer needed using feedback mechanisms.
• Electrical is a nerve impulse and chemical while Endocrine System produces hormones in the blood.
• Very fast signal for Nervous System but more slower for Endocrine System.
• Rapid decline for Nervous System vs months for endocrine.
• Highly specific where as Endocrine system is way less specific.
• Cells are specialized, performing specific functions. Cell gets a special shape and job to do something important for cell specialization.

Neuron Structure and Function

• Dendrites receive signals from other neurons or sensory cells.
• Nucleus contains DNA and acts as the control center.
• Soma (cell body) is responsible for general functions and processes information.
• Axon transmits electrical impulses away from the cell body.
• Myelin sheath insulates the axon and speeds up transmission.
• Schwann cells produce the myelin sheath in the PNS and help repair neurons.
• Oligodendrocytes produce the myelin sheath in the CNS.
• Nodes of Ranvier allow electrical impulses to jump, speeding up transmission.
• Axon terminals release neurotransmitters into the synapse.
• Homeostasis maintains a constant internal environment despite external changes.
• pH Levels stay within a certain range (around 7.35 to 7.45) to maintain proper function of cells
• Blood Sugar Levels are stable to allow providing energy during your cell functions.

Body Temperature

• Normal human body temperature should be about (98.6°F)
• If you're too hot, you sweat to cool down.
• If you're too cold, you shiver to warm up.
• Homeostasis detects change and releases a response to return the body back to its normal levels.

Receptors

• Mechanoreceptors detect touch, pressure, and vibration.
• Thermoreceptors detect temperature changes.
• Photoreceptors detect light.
• Chemoreceptors detect chemicals (taste, smell).
• Nociceptors detect pain.
• Proprioceptors detect body position and movement.
• Stimuli is a change in the body (e.g., body temperature increases). Specialized receptors (like thermoreceptors) sense the change.
• Receptors are sensory receptors detect the stimulus and generate an electrical signal.

Signal Transmissions

• Signal reaches the spinal cord, where it synapses (connects) with an interneuron which neurons that processes information.
• After processing the signal in the spinal cord, the signal is sent to a motor (efferent) neuron.
• The motor neuron activates an effector, typically a muscle causing the muscle to contract providing leading to a response such as removing the hand away.
• Example of a Reflex Arc (Withdrawal Reflex): You touch a hot object, causing pain and pain receptors occur.
• The sensory neuron carries the signal to the spinal cord.
• Examples include a monosynaptic reflex requiring only one synapse, and a polysynaptic reflex requiring one or more.

Eye Structure and Function

• The puncta drains excess tears.
• The iris controls pupil size, regulating light entering.
• The pupil is the opening for light and its functions are listed in detail above.
• The cornea bends light to help focus it onto the retina.
• The lens changes shape to focus light clearly (accommodation).
• The retina contains photoreceptors (rods, cones) and converts light into electrical signals.
• The optic nerve transmits visual signals from the retina to the brain.
• The ciliary body adjusts the lens with also produces aqueous humor.

Hearing

• Sound waves enter the pinna and move through the ear canal.
• Hit the eardrum, vibrated the ear drum.
• Vibrations pass through the smaller ossicles, which amplify them from anvil stirrup.
• The stirrup taps on the oval window, sending vibrations into the cochlea for final signal to enter the brain.
• The waves travel to brain which recognizes the information as a sound which comes from electrical signals that send it through the nervous system.
• If broken sound can be lost which would cause permeant hearing loss also known as can occur from over exposure to loud noises.

Ear

• Outer pinna collects a funnel to capture sound waves and give directional hearing.
• Ear Middle eardrum vibrate when vibrations get pushed too to hear sound.
• Middle ossicles are vibration that push for a hearing sound: Hammer and Anvil
• Amplify the vibrations (makes them stronger) before passing then sound reaches inner ear for oval vibrations;
• Inner ear Cochlea, sends three to the center so sound is in order to hear it well.

Brain

• Brain recivers electical through the nervous system to here the sounds loud a semi circular functions to create movement to have the proper directions to ensure the sound functions.
• Summary Table (Structure & Function):
• Pinna
• Collects sound and directs it into the ear canal.
• Ear Canal Chanels through and protects the inner structures.
• and it
• Eardrum vibrates with waves where begins.
• Ossicles are and and transform .
• Oval Windows into Cocthea.
• Cholea to reforms and to change systems.

Endocrine System & Gonads

• Endocrine system is communication from Glands that secrete hormones into blood These hormones help regulate all tissues aids
• Overtimes like is a change and the use is not like that so some of is that you need them
• Gland produces which make change .