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sci exam 1 > cylce test 2 yr 9 > Flashcards

cylce test 2 yr 9 Flashcards

electricity, radioactivity, homeostasis and body systems

1
Q

isotopes are:

A

atoms that have the same number of protons but different numbers of neutrons

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2
Q

atoms become radioactive when

A

they have unstable nuclei, either a nucleus is too big or has to many neutrons

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3
Q

what r the 3 types of radiation

A

alpha, beta, gamma

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4
Q

half life is:

A

the time taken for half a sample of radioactive substance to decay of for the activity in a substance to decrease by half

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5
Q

atoms with an unstable nuclei and are decaying are called

A

radioisotopes

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6
Q

alpha radiation has how many protons and neutron particles

A

2 protons and 2 neutrons (like helium -4)

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7
Q

radiation can be either:

A

particles or electromagnetic radiation (waves)

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8
Q

alpha particles have a charge of:

A

2+ (mass number 4)

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9
Q

are alpha particles, weakly ionising strongly ionising, or in the middle?

A

strongly ionising particles (can knock electrons out of orbit)

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10
Q

beta particles are made of

A

electrons (and hence have no mass)

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11
Q

beta particles are formed when

A

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)

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12
Q

gamma radiation is made of

A

electromagnetic rays (or waves)

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13
Q

beta radiation has a charge of

A

-1

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14
Q

gamma radiations charge is

A

none and theres no change in the nucleus taht released it either (apparently)

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15
Q

ionising means the

A

ability to knock electrons out of orbit or atoms

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16
Q

gamma radiation is how penetrating

A

the most, is only stopped by thick lead

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17
Q

alpha particles are the most ionising because:

A

they are the largest radioactive particles (2 protons and 2 neutrons

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18
Q

why aren’t alpha particles very penetrating

A

because the are very large (they are stopped by paper)

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19
Q

beta radiation is how penetration and ionising

A

medium for both, however it can pass through the human body and is still very ionising so it is the most dangerous

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20
Q

rocks can be dated by measuring

A

the ratio of uranium to lead atoms, this is because as the rock ages the uranium inside decays and transforms into lead.

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21
Q

radioactive decay is measured in:

A

decays per second measured in Becquerels (BQ) and can be measured with a geiger counter

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22
Q

activity is:

A

the overall rate of decays of all the isotopes in a sample

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23
Q

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)

A

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

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24
Q

we measure radioactivity with half lives because

A

the activity never reaches 0, so we can only measure it how much it decreases

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25
what is the amygdala?
the part of the brain that's most closely associated emotions and decision making
26
what are the 2 different types of circuits?
series and parralel
27
what is the law of conservation of energy?
energy cannot be destroyed or created only transferred or transformed
28
the formula for energy efficiency is:
useful output/total input x100
29
what is electricity?
the movement of electrons between atoms
30
electricity conductors do what to conduct electricity
they loosen the force of attraction between electrons and the nucleus
31
what is the symbol for current?
I
32
current is measured in:
Amperes (a)
33
what measures the current in a circuit?
ammeter (the symbol is a circle with an a in the middle)
34
electricity in a circuit comes from:
a battery and go to other components that transform it
35
voltage is measured using:
a voltmeter
36
voltmeter are measuring:
the potential difference btw two points
37
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)
38
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
39
what is voltage?
the amount of 'push' that the cell or battery can give the electrons
40
resistance is measured in:
ohms Ω
41
the formula for ohm law is:
R=v/i or v=i times R where current is i
42
mrs gren stands for:
movement, respiration, sensitivity, growth, reproduction, excretion, nutrition
43
aerobic respiration word equation is
oxygen+glucose=carbon dioxide+water (energy)
44
anaerobic respiration word equation is
glucose= lactic acid (energy) + carbon dioxide
45
respiration occurs in:
the mitochondria
46
the endocrine system is made up of
chemical messages (hormones) through blood, which is: slower, longer, and more generalised
47
the nervous system is made of
electrochemical messages (neurons) (electrical impulses) which are very fast and precise
48
what is the definition of homeostasis
the maintenance of a constant internal environment
49
what are the processes that homeostasis controls?
removal of co2, removal of urea, ion content, h2o content, sugar content, temp, ph
50
receptor cells do what?
detect stimuli
51
what are stimulus?
any change which brings about a response in the body
52
what is a control center?
organ that receives signals and makes a decision about what to do next
53
what is the effector?
an organ which receives signals from the control centra and carries out the instructions
54
what are responses?
actions carried out by the effector
55
chemo-receptors respond to: and are found in:
chemicals (eg smell and taste) nose, tongue
56
photoreceptors react to the: and are found in the:
light eyes, retina
57
mechanoreceptor react to the: and are found in the:
pressure or distortion skin, ears
58
thermoreceptors react to the: and are found in the:
temp skin
59
what is another word for nerve cells?
neurons
60
what is the cns?
central nervous system, brain and spine
61
what is the pns?
peripheral nervous system, connects to nerve cells outside of the cns
62
negative feedback does what?
counteracts change with an opposite reaction, eg body heat (homeostasis)
63
positive feedback does what?
amplifies a stimuli, eg blood clotting
64
what will happen if your temp is heightened?
enzymes will denature, meaning the active site changes shape
65
what happens when enzymes denature
their active site changes shape and the reaction can no longer happen at a speed that maintains life
66
what are the mechanisms that cool us down
blood vessels expand (vasodilate) erector muscles relax (hair), sweat is produced
67
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)
68
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)
69
how does vasoconstriction heat us
blood vessels near skin narrow, decreased blood flow to skin, decreased heat loss through blood + skin
70
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
71
how is co2 levels detected by the body
receptors in your brain detect ph levels that fluctuate with co2 levels
72
the somatic system is
voluntary responses part of the nervous system (pns) eg, moving/ walking
73
what is the autonomic system
involuntary response (part of the nervous system) eg responding to a flash of light
74
the sympathetic nervous system is
fight or flight responses
75
parasympathetic
calming responses (rest and digest)
76
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
77
what is the cerebrum
main part of brain (cerebral hemispheres) controls thoughts and action
78
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
79
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
80
what does a relay neuron do
connects sensory neuron to motor neuron
81
what do dendrites do
receive incoming signals from other neuron or sensory receptors and transmit these signals to the cell body
82
axons are
elongated projections that transmit nerve impulses away from the cell body of a neuron
83
what are the 3 types of neurons
motor neuron, relay neuron, sensory neuron
84
what do motor neurons do
carries messages from the cns to the effectors, eg muscles and glands
85
what do relay neurons do
transfers messages from sensory neurons to other interconnecting neurons or motor neurons
86
what do sensory neurons do
detect stimuli
87
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
88
what is a hormone
a hormone is a chemical produced by an endocrine gland that travels in the blood to activate target cells
89
what are target cells (endocrine)
cells that have receptor for specific hormones in order to enact he messages sent by the hormones
90
what are the organs that excrete hormones
pituitary, thyroid, pancreas, ovaries, testes, adrenal glands (kidneys
91
why is the pituitary gland called the master gland
because it produces several important hormones and controls the other glands
92
occipital lobes is responsible for?
visual perceptions eg. colour,
93
cerebellum controls:
movement and balance
94
what do axons do what do dendrites do
send recieve
95
difference between series and parallel:
parallel is same voltage, but ampage/current is shared

sci exam 1 (6 decks)

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