Semester 1 Exam 2025 - Homeostasis + Waves vocabulary

Homeostasis, nervous system, endocrine system, lenses, brain, eyes, light, sound, colour, types of waves, electromagnetic spectrum, reflection and refraction,

transverse wave

the medium vibrates perpendicular to the direction of movement

longitudinal wave

the particles in the medium vibrate horizontally. the wave moves parallel to the particles

medium

a substance or material which a pulse moves. carries the pulse, does not create the pulse.

crest

peak of a wave

trough

lowest point of a wave

wavelength

distance between crest to a crest, or a trough to a trough; length of a complete wave cycle, often linked with frequency

sound: longer = lower pitch, vv

light: longer = lower energy/brightness, vv

amplitude

height of the wave

sound: higher = louder, vv

light: higher = brighter, vv

frequency

the rate at which the wave moves; number of wave cycles per second, often linked with wavelength

sound: higher = higher pitch, vv

light: higher = higher energy/brightness, vv

compression

sections where particles are closest together in a particle model

rarefaction

sections where particles are furthest apart in a particle model

reflection: law of reflection

when something bounces back off a surface. the law of reflection suggests that the angle of reflection is always equal to the angle of incidence.

refraction

bending of light or sound as it passes through something (e.g. glass or water). The bending is caused due to the change in density or speed.

lower to higher density = bends towards the normal line

higher to lower density = bends away from the normal line

transmission

the transfer of energy between or through materials

how is sound transmitted to another medium?

sound particles in the air vibrate, which cause the next particle to vibrate, until it eventually reaches the target medium. (e.g. eardrum, then you can hear the sound)

lens

a piece of glass that is curved on at least 1 side used to refract light for different purposes

e.g. magnify objects, correct vision problems, etc.

convex lens

make light rays converge, thicker in the middle
can make the image larger or smaller.

larger images are formed when the object is located between the lens and focal point

smaller images are formed when the object is >2 focal lengths from the lens

concave lens

make light rays diverge, thinner in the middle
always make images seem smaller than reality.

label the eye

(sclera, cornea, iris, pupil, lens, vitreous humour, retina, optic nerve)

a) retina: thin layer of nerve tissue that detects light and converts into electrical signals

b) optic nerve: a nerve extending out of the eyeball that transmits information from the retina to the brain to be processed

c) lens: a flexible and transparent structure that focuses light onto the retina for clearer vision

d) vitreous humour: a gel-like substance that fills the inside of the eye and transmits light onto the retina

e) cornea: transparent and dome-shaped that refracts and focuses light entering the eye - acts as a protective barrier

f) pupil: opening in iris that regulates the amount of light entering the eye by contracting and expanding

g) iris: coloured part of the eye that controls the size of the pupil by adjusting to different lighting conditions

h) sclera: a tough, white outer layer that provides protection and structure to the eye

explain the double-slit light experiment

When two waves overlap, they interact. If their crests meet, their amplitudes add together, resulting in a brighter light (constructive interference). If a crest meets with a trough, their amplitudes cancel out, resulting in a dimmer light (destructive interference).

what happens to white light when it is refracted? why does this happen?

White light is composed of all colours of the rainbow. When refracted, each colour is refracted a different amount because of their difference in wavelengths and frequencies. Red has the lowest frequency, therefore refracts less, while violet has the highest frequency, therefore refracts more.

absorption

The transfer of light energy into an object which is then transformed into heat energy.

radio waves

• do not harm living things or the environment

• can pass through dense materials (i.e. concrete, buildings)

• have a low frequency, long wavelength

stimulus

a change in the internal or external environment that causes a response

receptor

a type of sense organs that detect stimuli

mechanical: related to senses touch and hearing
chemical: related to senses smell and taste - sensitive to chemicals in mouth and nose
electromagnetic: related to light (photoreceptor) and temperature (thermoreceptor)

effector

a part of the body that receives responses. becomes active in response to a stimulus.

response

the action taken as a result of a stimulus

negative feedback

counteracts the stimulus (stimulus ‘disappears’)
e.g. sweating in response to the rise in temperature

positive feedback

increases the stimulus (stimulus worsens)
e.g. contractions in childbirth cause worse contractions

central nervous system

brain and spinal cord. registers messages it receives from sense organs and coordinates responses to send to the muscles and glands

peripheral nervous system

nerves send messages between sense organs, CNS, the muscles and glands. spread entirely through the body.

somatic and autonomic nervous system

both found in the PNS

somatic: controls voluntary movements

autonomic: controls involuntary movements

sympathetic and parasympathetic divisions

both part of the autonomic nervous system

sympathetic division: fight or flight, prepares body for action

parasympathetic divions: rest and digest, calms body after action

motor neuron

sends response information away from the CNS to the muscles (efferent neuron)

sensory neuron

sends sensory information towards CNS (afferent neuron)

interneuron

sends messages between motor and sensory neurons. only found in the CNS (lacks the myelin sheath, axons are shorter)

synapse

gap between neurons that transfers neurotransmitters (chemical signals) from one neuron to another

left side of brain

analysis and logic, maths and language, reasoning

right side of brain

creativity, intuition, feelings and sight, arts, music and emotions

frontal lobe

decision-making, problem-solving and reasoning, planning, voluntary movement, personality, emotional regulation

parietal lobe

sensory perception (touch, temp., pain), spatial awareness, attention

occipital lobe

visual processing (the visual cortex), object recognition, colour perception, spatial vision (comprehending size, shape, etc)

temporal lobe

sound processing, memory formation and retrieval, language comprehension

cerebellum

coordination of movement, balance, muscle tone, motor learning

brain stem

receives sensory information from the peripheral nervous system and sends motor commands to the body

hypothalamus

maintains internal homeostasis. an endocrine gland that releases hormones that regulate the pituitary gland.

and:

• regulates the autonomic NS

• regulates the circadian rhythm (sleep-wake cycles)

• controls emotions

• regulates sexual behaviour and reproduction

diencephalon

controls sensations, weight regulation, energy and instinctual behaviours

endocrine system

produces and releases hormones to maintain homeostasis. regulates mood, growth, development, metabolism, reproduction, etc.

hormone receptors

target cells have specific receptors that recognise and bind into the hormone to be detected