cylce test 2 yr 9 Flashcards
electricity, radioactivity, homeostasis and body systems
isotopes are:
atoms that have the same number of protons but different numbers of neutrons
atoms become radioactive when
they have unstable nuclei, either a nucleus is too big or has to many neutrons
what r the 3 types of radiation
alpha, beta, gamma
half life is:
the time taken for half a sample of radioactive substance to decay of for the activity in a substance to decrease by half
atoms with an unstable nuclei and are decaying are called
radioisotopes
alpha radiation has how many protons and neutron particles
2 protons and 2 neutrons (like helium -4)
radiation can be either:
particles or electromagnetic radiation (waves)
alpha particles have a charge of:
2+ (mass number 4)
are alpha particles, weakly ionising strongly ionising, or in the middle?
strongly ionising particles (can knock electrons out of orbit)
beta particles are made of
electrons (and hence have no mass)
beta particles are formed when
when the ratio of neutrons to protons is too high (excess neutrons are transformed into a proton and an electron) the protons stays and the electron is ejected as beta radiation)
gamma radiation is made of
electromagnetic rays (or waves)
beta radiation has a charge of
-1
gamma radiations charge is
none and theres no change in the nucleus taht released it either (apparently)
ionising means the
ability to knock electrons out of orbit or atoms
gamma radiation is how penetrating
the most, is only stopped by thick lead
alpha particles are the most ionising because:
they are the largest radioactive particles (2 protons and 2 neutrons
why aren’t alpha particles very penetrating
because the are very large (they are stopped by paper)
beta radiation is how penetration and ionising
medium for both, however it can pass through the human body and is still very ionising so it is the most dangerous
rocks can be dated by measuring
the ratio of uranium to lead atoms, this is because as the rock ages the uranium inside decays and transforms into lead.
radioactive decay is measured in:
decays per second measured in Becquerels (BQ) and can be measured with a geiger counter
activity is:
the overall rate of decays of all the isotopes in a sample
prac question, the half life of a radioactive source is 40 hours, there are originally 3000000 radioactive nuclei in the sample. how may nuclei will remain after 5 days?
(skip this if your reading it mum)
24 hours times 5 days = 120 hours
120 divided by 40 = 3 half lives
300000 divided by 2 = 1500000
1500000 divided by 2 = 750000
750000 divided by 2 =
375000 answer
we measure radioactivity with half lives because
the activity never reaches 0, so we can only measure it how much it decreases
what is the amygdala?
the part of the brain that’s most closely associated emotions and decision making
what are the 2 different types of circuits?
series and parralel
what is the law of conservation of energy?
energy cannot be destroyed or created only transferred or transformed
the formula for energy efficiency is:
useful output/total input x100
what is electricity?
the movement of electrons between atoms
electricity conductors do what to conduct electricity
they loosen the force of attraction between electrons and the nucleus
what is the symbol for current?
I
current is measured in:
Amperes (a)
what measures the current in a circuit?
ammeter (the symbol is a circle with an a in the middle)
electricity in a circuit comes from:
a battery and go to other components that transform it
voltage is measured using:
a voltmeter
voltmeter are measuring:
the potential difference btw two points
voltmeters compare the difference between points by:
by comparing the energy electrons have before and after going through a component (voltmeter resistance is negligible so the current passes straight through them)
the more resistance…
the less current can flow (form the same amount of voltage push) or a measure of the amount of energy supplied to the charges or used up by the component the current passes through
what is voltage?
the amount of ‘push’ that the cell or battery can give the electrons
resistance is measured in:
ohms Ω
the formula for ohm law is:
R=v/i or v=i times R where current is i
mrs gren stands for:
movement, respiration, sensitivity, growth, reproduction, excretion, nutrition
aerobic respiration word equation is
oxygen+glucose=carbon dioxide+water (energy)
anaerobic respiration word equation is
glucose= lactic acid (energy) + carbon dioxide
respiration occurs in:
the mitochondria
the endocrine system is made up of
chemical messages (hormones) through blood, which is: slower, longer, and more generalised
the nervous system is made of
electrochemical messages (neurons) (electrical impulses) which are very fast and precise
what is the definition of homeostasis
the maintenance of a constant internal environment
what are the processes that homeostasis controls?
removal of co2, removal of urea, ion content, h2o content, sugar content, temp, ph
receptor cells do what?
detect stimuli
what are stimulus?
any change which brings about a response in the body
what is a control center?
organ that receives signals and makes a decision about what to do next
what is the effector?
an organ which receives signals from the control centra and carries out the instructions
what are responses?
actions carried out by the effector
chemo-receptors respond to:
and are found in:
chemicals (eg smell and taste)
nose, tongue
photoreceptors react to the:
and are found in the:
light
eyes, retina
mechanoreceptor react to the:
and are found in the:
pressure or distortion
skin, ears
thermoreceptors react to the:
and are found in the:
temp
skin
what is another word for nerve cells?
neurons
what is the cns?
central nervous system, brain and spine
what is the pns?
peripheral nervous system, connects to nerve cells outside of the cns
negative feedback does what?
counteracts change with an opposite reaction, eg body heat (homeostasis)
positive feedback does what?
amplifies a stimuli, eg blood clotting
what will happen if your temp is heightened?
enzymes will denature, meaning the active site changes shape
what happens when enzymes denature
their active site changes shape and the reaction can no longer happen at a speed that maintains life
what are the mechanisms that cool us down
blood vessels expand (vasodilate) erector muscles relax (hair), sweat is produced
mechanisms to heat us up
constrict blood vessels (vasoconstriction), contract erector vessels (hair stands on end and traps insulating air) muscles move (shivering) generates energy from respiration (creates heat energy as waste)
why does vasodilation cool us down
the blood vessels near the skin widen which increases blood flow near skin so increases heat loss (more surface area and blood flow)
how does vasoconstriction heat us
blood vessels near skin narrow, decreased blood flow to skin, decreased heat loss through blood + skin
when you use anaerobic respiration what happens
lactic acid builds up in muscles, oxygen dept occurs, it is also less efficient then aerobic (but still better option)but sometimes necessary
how is co2 levels detected by the body
receptors in your brain detect ph levels that fluctuate with co2 levels
the somatic system is
voluntary responses part of the nervous system (pns) eg, moving/ walking
what is the autonomic system
involuntary response (part of the nervous system) eg responding to a flash of light
the sympathetic nervous system is
fight or flight responses
parasympathetic
calming responses (rest and digest)
the spinal cord is
part on the cns, it is a bundle of nerves that extend form the base of the brain to the spinal column, main pathway for transmitting signals between brain and body, coordinates reflexes, protected by vertebra
what is the cerebrum
main part of brain (cerebral hemispheres) controls thoughts and action
what is a myelin sheath and what does it do
a fatty layer that coats the neurons near axons it insulates the electricity so sinals are maintained
what happens in synapses
in the joins of neurons (synapses, empty space) the electrical signals are converted to chemical and transferred to the next neuron
what does a relay neuron do
connects sensory neuron to motor neuron
what do dendrites do
receive incoming signals from other neuron or sensory receptors and transmit these signals to the cell body
axons are
elongated projections that transmit nerve impulses away from the cell body of a neuron
what are the 3 types of neurons
motor neuron, relay neuron, sensory neuron
what do motor neurons do
carries messages from the cns to the effectors, eg muscles and glands
what do relay neurons do
transfers messages from sensory neurons to other interconnecting neurons or motor neurons
what do sensory neurons do
detect stimuli
what is the order of operations from when your body detects stimulus to the response
stimulus, receptors, sensory neurons,relay neurons, motor neurons, effectors, response
what is a hormone
a hormone is a chemical produced by an endocrine gland that travels in the blood to activate target cells
what are target cells (endocrine)
cells that have receptor for specific hormones in order to enact he messages sent by the hormones
what are the organs that excrete hormones
pituitary, thyroid, pancreas, ovaries, testes, adrenal glands (kidneys
why is the pituitary gland called the master gland
because it produces several important hormones and controls the other glands
occipital lobes is responsible for?
visual perceptions eg. colour,
cerebellum controls:
movement and balance
what do axons do
what do dendrites do
send
recieve
difference between series and parallel:
parallel is same voltage, but ampage/current is shared
