Science Flashcards
(394 cards)
1
Q
Define cell
A
The basic unit of living things
2
Q
Name five organelles in animal and plant cells
A
Nucleus, cytoplasm, cell membrane, ribosome, mitochondria
3
Q
Name three organelles only in plant cells
A
Cell wall, chloroplasts, vacuole
4
Q
Define eukaryotic cell
A
A cell with a true nucleus
5
Q
Define prokaryotic cell
A
A cell without a true nucleus
6
Q
Give the function of the nucleus
A
Controls all activities of the cell
7
Q
Give the function of the ribosomes
A
Protein synthesis
8
Q
Give the function of the mitochondria
A
Does aerobic respiration which produces energy
9
Q
Give the function of the cytoplasm
A
Chemical reactions
10
Q
Give the function of the cell membrane
A
Controls the movement of substances in and out of the cell
11
Q
Give the function of the cell wall
A
Provides structure and support
12
Q
Name the chemical that makes the cell wall
A
Cellulose
13
Q
Give the function of the chloroplasts
A
Photosynthesis
14
Q
What is active transport
A
Movement of a substance from a dilute to more concentrated solution against a a concentration gradient. Requires energy
15
Q
3 stages of the cell cycle
A
Replication, mitosis, division
16
Q
What happens during replication
A
DNA is copied
17
Q
What happens during mitosis
A
Contents of cell are rearranged and nucleus divides
18
Q
What happens during cell division
A
Two identical daughter cells are produced
19
Q
Define stem cell
A
Unspecialised cell
20
Q
Define differentiation
A
Process by which a cell becomes specialised
21
Q
Three types of stem cell
A
Embryonic, adult and plant
22
Q
Advantages of embryonic stem cells
A
Can differentiate into most types of cells
23
Q
Where are adult stem cells found
A
Bone marrow
24
Q
Where are plant stem cells found
A
Meristem tissue
25
Define cell
Basic unit of living things
26
Define tissue
Groups of similar cells performing the same function
27
Define organ
Groups of tissues doing the same function
28
Define organ system
Groups of organs performing the same function
29
List 3 types of tissue
Muscular, glandular and epithelial
30
What does bile do
Neutralises stomach acid and breaks down fats
31
Name the organ where bile is produced
Liver
32
Name the organs involved in digestion
Mouth
Oesophagus
Stomach
Liver
Small intestine
Large intestine
Anus
33
Give the function of the small intestine
Reabsorbs glucose from digested food
34
Adaptations of small intestine
Lots of microvilli, good blood supply, thin walls, lots of mitochondria
35
Name the substance the stomach contains
Hydrochloric acid (pH 3)
36
Part of the digestive system responsable for reabsorbing water
Large intestine
37
Test for starch
Iodine solution
( positive result = turns dark blue/ black)
38
Test for simple sugars ( glucose )
Bendedicts solution - turns brick red when heated
39
Test for protein
Biuret solution - turns purple
40
Test for lipids
Ethanol - milky emulsion is formed
41
What are proteins broken down into
Amino acids
42
What are carbohydrates broken down into
Glucose
43
What are lipids broken down into
Glycerol and fatty acids
44
Define enzyme
Biological catalyst
45
Name the 3 types of digestive enzyme
Amylase
Proteases
Lipases
46
Where is amylase produced
Mouth
Pancreas
Small intestine
47
Where is protease produced
Stomach
Pancreas
Small intestine
48
Where is lipase produced
Pancreas
Small intestine
49
What happens to an enzyme when the temperature is too hot
Denatures
50
4 components of blood
Red blood cells
White blood cells
Platelets
Plasma
51
Function of red blood cells
Carry oxygen
52
3 functions of white blood cells
Engulf pathogens
Make antitoxins
Make antibodies
53
Function of platelets
Clot the blood
54
Function of plasma
Transports substances around the body
55
3 types of blood vessel
Artery
Vein
Capillary
56
Structure of artery
Thick walls
Small lumen
57
Function of artery
Carries oxygenated blood ant high pressure away from the heart
58
Structure of a vein
Thin walls
Large lumen
Valves to prevent backflow
59
Function of a vein
Carries deoxygenated blood at low pressure toward the heart
60
Structure of capillary
Small lumen
Walls one cell thick
61
Function of capillary
Links arteries and veins
To help with diffusion
62
4 chambers in the heart
Right atrium
Right ventricle
Left atrium
Left ventricle
63
Where are the 2 atria found
Top of the heart
64
Where are the 2 ventricles found
Bottom of the heart
65
Which side of the heart pumps oxygenated blood
Left
66
Which side of the heart pumps deoxygenated blood
Right
67
Function of valves in the heart
Stop blood flowing backwards
68
Blood vessel that take deoxygenated blood to the lungs
Pulmonary artery
69
Blood vessel through which oxygenated blood is pumped to the body
Aorta
70
3 methods of treating cardiovascular disease
Drugs
Mechanical devices (stents/ pacemakers)
Transplants
71
Define coronary heart disease
The narrowing of coronary arteries due to a buildup of fat. This reduces the amount of oxygen reaching the heart and can cause heart attacks.
72
4 plant organs
Roots
Stem
Leaves
Flowers
73
3 tissues in a leaf
Upper/ lower epidermis
Palisade mesophyll
Spongy mesophyll
74
Function of the xylem
Transport water and minerals ions from roots to leaves
75
Function of the phloem
Transports dissolved sugars from the leaves using translocation
76
Define stomata
Pores on the underside of a leaf
Controlled by guard cells
77
Define transpiration
Evaporation of water via the stomata
78
Four factors that affect the rate of transpiration
Light, temperature, wind, humidity
79
Describe communicable disease
Contagious. Caused by pathogens.
80
Describe noncommunicable disease
Non-contagious. Not caused by pathogens.
81
Define pathogen
Microorganisms that cause disease
82
Four types of pathogen
Bacteria, virus, fungi, protist
83
Explain how bacteria cause diseases
Produce toxins
84
Explain how viruses cause diseases
Take over and destroy cells
85
Describe how pathogens are spread
Air, water, direct contact
86
Ways to prevent infection spreading
Hygiene, isolation, destroying vectors, vaccines/antibiotics
87
List three viral diseases
Measles, HIV/AIDS, tobacco mosaic virus (TMV)
88
Describe characteristics of measles
Spread by air. Causes fever and red rash. No treatment, vaccination prevent spread
89
Characteristics of HIV/AIDS
Spread by sexual contact/exchange of body fluids. Causes flu like illness and attacks immune system.
90
Describe characteristics of TMV
Spread by direct contact, and insect vectors. Reduces photosynthesis and growth because leaves lack chlorophyll.
91
List two bacterial diseases
Salmonella, gonorrhoea
92
Describe characteristics of salmonella
Spread by unhygienic food. Causes, stomach, cramps, diarrhoea, and vomiting
93
Describe characteristics of gonorrhoea
Caused by sexual contact. Causes thick, yellow/green discharge and pain on urination. treated with antibiotics.
94
Describe rose black spot
Fungal disease. Causes black spots on leaves. Reduces photosynthesis and growth. Spread in the air and rain.
Treated by fungicides removing/burning infected leaves.
95
Describe malaria
Protist disease. Spread by mosquitoes, infects, red blood cells, and liver.
Causes, fever, shaking, and weakness.
96
How are bacterial infections treated
Antibiotics
97
Describe how viral infections are treated
Vaccinations/antiretroviral drugs
98
Explain why antibiotics cannot be used to treat viral infections
Difficult to develop drugs that kill viruses without damaging bodies tissues
99
Describe what painkillers do
Treat symptoms, but don’t kill pathogens
100
Explain how a vaccine works
Contains dead/inactive pathogens
White blood cells make antibodies that kill the pathogen
White blood cells, remember the antibodies and respond quicker to the future injections
101
Define herd immunity
Reducing the spread of the disease by vaccinating a large proportion of a population. Reduces the spread of the pathogen.
102
Define penicillin
An antibiotic produced from penicillium mould
103
Who discovered penicillin?
Alexander Fleming
104
Define antibiotic resistant bacteria
Strains of bacteria that have evolved resistance to antibiotics
105
Define clinical trials
Research studies involving human patients
106
Define a placebo
A medicine that does not contain the active drug
107
Define a double blind trial
When the doctor and patient don’t know who received the drug. Reduces bias.
108
Define noncommunicable disease
Cannot be spread. Not caused by pathogens e.g. cancer.
109
Define carcinogen
Chemicals that cause cancer, e.g. tar
110
Define mutation
Change in the DNA/genetic material
111
Define tumour
Bundle of abnormal cells, dividing rapidly and out of control
112
Define benign tumour
Contained in one place, usually within a membrane. Doesn’t spread or invade other tissues.
113
Define malignant tumour
Invade other tissues spread to other parts of the body in the blood. Secondary tumours form.
114
Describe how cancer can be treated
Radiotherapy, chemotherapy
115
Describe her radiotherapy works
Using ionising radiation to kill cancer cells
116
Describe how chemotherapy works
Uses chemicals to kill cancer cells
117
Three Harmful substances in cigarette smoke.
Nicotine, tar, carbon monoxide
118
Name the addictive substance in cigarette smoke
Nicotine
119
Name the carcinogenic substance in cigarette smoke
Tar
120
What is the harmful effects of carbon monoxide?
Stops red blood cells carrying oxygen. Can cause dizziness/sickness and death.
121
Why is alcohol harmful?
It’s poisonous and addictive
122
Why should pregnant women avoid alcohol?
Can cause foetal alcohol syndrome
Can cause stillbirths and miscarriages
Low birth weight and premature births
123
Different tissues in a leaf
Wax cuticles, upper/lower epidermis, palisade mesophyll, spongy mesophyll , stomata
124
Give the role of the upper/lower epidermis
Skin like, protective layer
125
Give the role of the palisade mesophyll cells
Photosynthesis.
They are found at the top of the leaf and contain chloroplasts
126
Give the role of the spongy mesophyll cells
Air spaces to allow gases to diffuse
127
What resources are needed for photosynthesis?
Water
Sunlight
Carbon dioxide
128
What are the products of photosynthesis
Oxygen and glucose
129
Give the word equation for photosynthesis
Carbon dioxide + water ——>glucose + oxygen
130
What would a plant use glucose for?
Respiration
Store as starch. As an energy store.
Making proteins, fat and oils for growth and repair
131
Three factors that affect the rate of photosynthesis
Temperature
Light intensity
Carbon dioxide
132
Name the organelle where respiration takes place
Mitochondria
133
What is the difference between breathing and respiration?
Respiration = chemical process in cells
Breathing = physical process in lungs
134
Name the two types of respiration
Aerobic
Anaerobic
135
What does respiration release?
Energy
136
Why is respiration important?
Growth and repair
Muscle contraction
Maintains body temperature
Active transport
137
Word equation for aerobic respiration
Glucose + oxygen —>carbon dioxide + water
138
Word equation for anaerobic respiration
During exercise
Glucose —> lactic acid
After exercise
Lactic acid + oxygen —> carbon dioxide + water
139
What is lactic acid?
Poisonous waste product, causes cramps
140
How would your body get rid of lactic acid?
React with oxygen
141
What is oxygen debt?
Amount of oxygen needed to get rid of lactic acid
142
Define fermentation
Anaerobic respiration in micro organisms
143
Word equation for anaerobic respiration in plants?
Glucose —> ethanol + carbon dioxide
144
Name the 3 subatomic particles
Protons, neutrons, and electrons
145
What are the two subatomic particles in the nucleus?
Protons and neutrons
146
Where are electrons found in the atom?
Orbiting the nucleus in shells
147
What is the charge of a proton?
Positive (+1)
148
What is the charge of a neutron?
Neutral (0)
149
Give the charge of an electron
Negative (-1)
150
Define an atom
Smallest particle that makes up all matter
151
Define an element
Substance is made from only one type of atom
152
Define a compound
Substances made from two or more types of atoms bonded together
153
Define a mixture
Groups of atoms, elements and compounds that are mixed, but not bonded
154
Define an ion
Charged particle formed when an atom has lost or gained electrons
155
Define isotope
Atoms of the same element (same number of protons) with a different number of neutrons
156
Name the process to separate two liquids
Distillation
157
Name the process to separate an insoluble solid from a liquid
Filtration
158
Name the process to separate a soluble solid from a liquid
Crystallisation
159
Name the four scientists involved in the development of the periodic table
Dalton, Newlands, Mendeleev, Moseley
160
Describe the contribution of Dalton to the development of the periodic table
Ordered elements based on their atomic mass
161
Describe the contribution of Newlands to the development of the periodic table
Kept atomic mass, discovered a repeating pattern every eighth element
162
Describe the contribution of Mendeleev to the development of the periodic table
Switched positions of elements that did not fit patterns. left gaps for undiscovered elements
163
Describe the contribution of Moseley to the development of the periodic table
Ordered elements based on the number of protons they had
164
Give the properties of alkali metals
Very reactive
Low MP/BP
React well with water and halogens
165
Give the properties of the halogens
Low MP/BP
Poor conductors of heat/electricity
Toxic
React with alkali metals
166
Give the properties of noble gases
Very unreactive
Stable
Full outer shells
Exist as single atoms
167
What is the pattern of reactivity in group one? (alkali metals)
Alkali metals are more reactive down the periodic table
168
What is the pattern of reactivity in group 7 (halogens)
The halogens become less reactive as you go down the periodic table
169
Word equation for the reaction between an alkali metal and water
Alkali metal + water —> alkali metal hydroxide + hydrogen
170
Define displacement reaction
One more reactive element takes the place of a less reactive element in a compound
171
What are the three types of bonding?
Ionic
Covalent
Metallic
172
What type of bonding occurs between metals?
Metallic
173
What type of bonding occurs between metals and nonmetals?
Ionic
174
What type of bonding occurs between nonmetals?
Covalent
175
What happens in ionic bonding?
Electrons are lost or gained
176
What happens during covalent bonding?
Electrons are shared
177
Properties of ionic compounds
High MP/BP
Conduct electricity when molten/dissolved
Brittle
178
What structure do ionic compounds form?
Giant lattices
179
Why do ionic compounds have high melting/boiling points?
Strong electrostatic forces between oppositely charged ions, lots of energy needed to overcome them.
180
Why do simple covalent molecules have low, melting/boiling points?
Weak intermolecular forces between molecules, these are easily overcome
181
What material are diamond graphene and graphite made from?
Carbon atoms
182
Why is diamond hard and strong?
For covalent bonds per atom maximum number of bonds
lots of energy required to break them
183
Define atomic number
The number of protons in the nucleus of an atom
184
Define mass number
Number of protons, plus the number of neutrons
185
Define relative formula mass
The mass of a molecule
186
How do you calculate % by mass?
(Ar of the element / Mr of the compound) x 100
187
What is the equation for calculating concentration?
Concentration = mass/volume
188
State the units for concentration
g/dm*3
189
What are the metals that can be extracted using carbon?
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum
190
What metals can only be extracted using electrolysis
Potassium
Sodium
Calcium
Magnesium
Aluminium
191
Word equation for the reaction between a metal and oxygen?
Metal + oxygen —> metal oxide
192
Word equation for reaction between metal and acid
Metal + acid —> salt + hydrogen
193
Word equation for the reaction between metal oxide and carbon
Metal oxide + carbon —> metal + carbon dioxide
194
What is the word equation for the reaction between an acid and a base
Acid + base —> salt + water
195
Word equation for the reaction between metal carbonate and acid
Metal carbonate + acid —> salt + water + carbon dioxide
196
Word equation for the reaction between metal and water
Metal + water —> metal hydroxide + hydrogen
197
Define ore
A rock that contains enough metal atoms to make extracting them commercially viable
198
Define oxidation
Loss of oxygen, loss of electrons
199
Define reduction
Addition of oxygen, gain of electrons
200
Which ion makes a substance, acidic
H.+
201
Which ion makes a substance, alkaline
0H -
202
Define base
Chemicals capable of neutralising acids
203
Define alkali
Soluble base
204
Define electrolysis
Splitting a compound, using electricity
205
State the type of compound that can be split by electrolysis
Ionic compounds
206
State the type of element forms cations
Metals
207
State the type of element forms anions
Nonmetals
208
State the name of the positive electrode
Anode
209
State the name of the negative electrode
Cathode
210
What is an exothermic reaction?
A reaction that transfers energy from the react in chemicals to the surrounding area
211
Define endothermic reaction
A reaction that transfers energy from the surrounding area to the reactant chemicals
212
Define activation energy
The minimum energy needed for reaction to take place
213
Define bond, energy
The energy required to break a specific chemical bond
214
Give an example of an exothermic reaction
Fireworks
Combustion
Handwarmers
215
Give an example of an endothermic reaction
Thermal decomposition
Ice packs
216
Is making bonds exothermic or endothermic
Exothermic
217
Is breaking bonds, exothermic or endothermic
Endothermic
218
Define energy
The ability for something to do work
219
Define conservation of energy
Energy can’t be created or destroyed, but it can transfer between stores
220
What is energy measured in?
Joules
221
What are the seven energy stores?
Nuclear
Elastic
Electromagnetic
Kinetic
Gravitational potential
Chemical
Thermal
222
Word equation for calculating weight
Weight = mass x gravity
223
Equation for calculating work done
Work done = force x distance
224
Word equation for calculating kinetic energy
Kinetic energy = 0.5 x mass x speed*2 turn
225
Equation for calculating gravitational, potential energy
GPE = mass x gravity x change in height
226
Equation for calculating efficiency
Efficiency = useful output (energy or power)/total input (energy or power)
227
What are the equation for calculating power?
Power = work done/time
Power = energy transferred/time
228
Define power
The amount of energy transferred by an object each second
229
What is power measured in?
Watts
230
Define thermal conductivity
The ability of a material to transfer energy by heating
231
Define a conductor
A material with a high thermal conductivity
232
Define an insulator
A material with low thermal conductivity
233
Define conduction
The transfer of energy through material by the vibration of an atoms
234
Define convection
The circulation of the fluid caused by increasing its thermal energy
235
Define specific heat capacity
The amount of energy needed to raise the temperature of 1 kg substance by 1•c
236
Define fuels
Substances that release energy when burned
237
Define fossil fuels
Fuels made from dead animals and plants. nonrenewable
238
Define biofuel
Fuels made directly from plant material .renewable
239
Define renewable
It is replaced at the rate it is being used
240
What are the different forms of renewable energy?
Biofuels
Solar
Wind
Wave
Tidal
Hydroelectric
Geothermal
241
Describe how a power station works
Fuels are burnt to release steam
Steam turn the turbine
Generator makes electricity
Transformer sets correct voltage
242
Define electrical current
Flow of charge from positive to negative terminal of a battery
243
Describe what an electrical current is made up of
Moving electrons
244
Give the unit for current
Amps (A)
245
How do you measure current?
With an ammeter, connected in series
246
What is potential difference?
Work done between two points in a circuit
247
What is the unit for potential difference?
Volts (V)
248
How do you measure potential difference?
With a voltmeter, connected in parallel
249
Define resistance
Materials that oppose the flow of current
250
Give the unit for resistance
Ohms
251
What is a series circuit?
When all components are connected in the same loop
Current has one path to flow in
252
What is a parallel circuit?
Components can be set up in different loops. The current has more than one path to flow in.
253
Word equation to calculate potential difference?
Potential difference = current x resistance
V = IR
254
What equation links power current and potential difference?
Power = current x potential difference
255
Define alternating-current
An electric current repeatedly changes direction
256
Define direct current
An electric current that flows in One Direction
257
What is the blue wire in a cable?
Neutral wire
258
What is the brown wire and cable?
Live wire. Carries the 230 V alternating potential difference.
259
What is the green and yellow wire in a cable?
Earth wire. Safety feature that prevents electric shocks
260
three equation for calculating power?
Power = energy /time
Power = current x potential difference
Power = current*2 x resistance
261
Define National Grid
Network of cables and transformers, connecting, electricity producers to users
262
Equation for calculating density
Density = mass/volume
263
3 types of radiation
Alpha
Beta
Gamma
264
Properties of alpha radiation
Helium nucleus
Positively charged
Most ionising
Least penetrating
Most dangerous at short distances
Stopped by paper
265
Properties of beta radiation
High energy electron
Negatively charged
Medium ionisation and penetration
Most dangerous at mid distances
Stopped by aluminium
266
List of properties of gamma radiation
Electromagnetic wave
No charge
Least ionising
Most penetrating
Most dangerous at long distances
Stopped by concrete
267
What is half life?
Time taken for radiation levels to decrease by 50%
268
Where in the heart is the pacemaker found
Right atrium
269
Where in the heart is the pacemaker found
Right atrium
270
How do the tissues in the stomach allow it to function
Muscular tissue
- to churn the contents
Glandular tissue
- to produce digestive juices
Epithelial tissue
- to cover inside/ outside of the stomach
271
What are enzymes made of
Protein
272
First 4 helpful learning thoughts
1- I can do it
2- this will help my future
3- I want to be able to do my work faster
4- I’ll have more time to learn and do other things
273
Second three helpful learning thoughts
5-how can I make this more fun
6- I can use these skills in other areas
7- I can have more spare time
274
Last three helpful learning thoughts
8- this will compound my growth and rewards
9- I’m excited to reach my maximum learning potential
10- I’ll be ahead of other students: people
275
276
What is a solenoid?
Long coils of insulated wire
277
278
What is the aim of the rates of reaction required practical?
To investigate how the concentration of a reactant affects the rate of a chemical reaction.
279
What is a common example reaction for the rates practical?
Reacting sodium thiosulfate with hydrochloric acid and measuring time for the cross to disappear.
280
What is the independent variable in the rates practical?
The concentration of the acid or sodium thiosulfate.
281
What is the dependent variable in the rates practical?
Time taken for the reaction or the rate of reaction.
282
What is the control variable in the rates practical? (Covering the cross)
Temperature
283
What theory does the rates practical demonstrate?
Collision theory and the effect of concentration on rate.
284
What is the aim of the chromatography required practical?
To separate components of a mixture and identify them using paper chromatography.
285
What materials are used in chromatography?
Filter paper
286
What is the Rf value equation?
Rf = distance moved by substance ÷ distance moved by solvent.
287
What must be used to draw the baseline in chromatography?
A pencil
288
What does chromatography help you identify?
The different substances present in a mixture based on solubility.
289
What is the aim of the qualitative analysis required practical?
To identify cations and anions using chemical tests.
290
291
292
What happens when NaOH is added to Al³⁺ and Ca²⁺?
Both form white precipitates
293
What is the test for carbonate ions?
Add dilute acid — if it fizzes
294
How do you test for halide ions?
Add nitric acid then silver nitrate.
295
What are the colours of halide precipitates?
Chloride = white
Bromide = cream
Iodide = yellow
296
What is the test for sulfate ions?
Add hydrochloric acid then barium chloride — a white precipitate forms.
297
Why is hydrochloric or nitric acid added before halide/sulfate tests?
To remove other ions that might interfere with the test.
298
What colour flame does lithium (Li⁺) produce?
Red
299
What colour flame does sodium (Na⁺) produce?
Yellow
300
What colour flame does potassium (K⁺) produce?
Lilac
301
What colour flame does calcium (Ca²⁺) produce?
Orange-red
302
What colour flame does copper (Cu²⁺) produce?
Green
303
What is the difference between scalar and vector quantities?
Scalar has only magnitude; vector has magnitude and direction.
304
What is the equation for weight?
Weight = mass × gravitational field strength
305
What is a resultant force?
The overall force when multiple forces act on an object
306
What happens when work is done on an object?
Energy is transferred
307
What does Hooke’s Law state?
Force = spring constant × extension (F = k × e)
308
What is the limit of proportionality?
The point beyond which extension is no longer proportional to force
309
What is a moment?
The turning effect of a force = force × distance from pivot
310
How can you increase the moment of a force?
Increase the force or distance from the pivot
311
Why does pressure in a fluid increase with depth?
Because there's more weight of fluid above
312
What causes atmospheric pressure to decrease with altitude?
Fewer air molecules higher up
313
What is the difference between distance and displacement?
Distance is scalar; displacement is vector
314
What is the difference between speed and velocity?
Speed is scalar; velocity is vector
315
What does the area under a velocity-time graph represent?
Distance travelled
316
What does the gradient of a velocity-time graph show?
Acceleration
317
State Newton’s First Law.
An object will remain at rest or in constant motion unless acted on by a resultant force
318
State Newton’s Second Law.
Force = mass × acceleration
319
State Newton’s Third Law.
For every action there is an equal and opposite reaction
320
What affects a vehicle’s braking distance?
Speed, road conditions, tyre/brake condition
321
What is momentum?
Momentum = mass × velocity
322
What does conservation of momentum mean?
Total momentum before = total momentum after (in a closed system)
323
How do crumple zones and seatbelts reduce injury?
They increase the time over which momentum changes, reducing force
324
325
What are transverse waves?
Waves with oscillations perpendicular to the direction of energy transfer
326
What are longitudinal waves?
Waves with oscillations parallel to the direction of energy transfer
327
What is the difference between frequency and period?
Frequency = number of waves per second; period = time for one wave
328
What is the relationship between wave speed, frequency and wavelength?
Wave speed = frequency × wavelength
329
What is the law of reflection?
Angle of incidence = angle of reflection
330
What causes refraction?
Wave speed changes when entering a different medium
331
Name the electromagnetic spectrum in order.
Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma
332
Which EM waves are ionising?
Ultraviolet, X-rays, Gamma rays
333
What is infrared radiation used for?
Heating and thermal imaging
334
What is UV radiation used for?
Fluorescent lamps, security marking, sunbeds
335
What is the danger of X-rays and Gamma rays?
Can cause mutations and cancer
336
How do sound waves travel?
As longitudinal waves through solids, liquids, or gases
337
What happens to sound when it enters a denser medium?
It speeds up
338
What does the frequency of a sound wave affect?
The pitch of the sound
339
What is ultrasound used for?
Imaging (e.g. foetal scans) and detecting flaws in materials
340
What are seismic waves?
Waves that travel through the Earth from earthquakes
341
What is the difference between P-waves and S-waves?
P-waves are longitudinal and travel through solids and liquids; S-waves are transverse and only travel through solids
342
343
What do magnetic field lines show?
The direction and strength of a magnetic field
344
What is the difference between permanent and induced magnets?
Permanent magnets always produce a field; induced magnets are temporary
345
What does the motor effect describe?
A force experienced by a current-carrying wire in a magnetic field
346
What factors affect the force in the motor effect?
Strength of magnetic field, current, and length of wire
347
What is an electric motor?
A device that uses the motor effect to produce rotation
348
How can a potential difference be induced?
By moving a conductor in a magnetic field or changing the magnetic field
349
What is the difference between an alternator and a dynamo?
Alternator produces AC; dynamo produces DC
350
How do microphones work?
Sound waves move a diaphragm that induces a current in a coil
351
How do loudspeakers work?
AC current causes coil to move in a magnetic field, producing sound
352
What does a transformer do?
Changes the potential difference of an alternating current
353
What is the role of a step-up transformer?
Increases voltage, decreases current
354
Why is a step-up transformer used in the National Grid?
To reduce energy loss from heating
355
What does a step-down transformer do?
Decreases voltage for safe use in homes
356
Why does the National Grid use high voltage?
To reduce current and energy loss by heating
357
358
What objects make up the solar system?
Sun, planets, dwarf planets, moons, comets, asteroids
359
What force keeps planets in orbit around the Sun?
Gravitational force
360
What is the order of star formation?
Nebula → Protostar → Main sequence → Red giant/supergiant → White dwarf/supernova
361
What is a protostar?
A collapsing cloud of gas and dust where fusion is starting
362
What is a main sequence star?
A stable star where gravity is balanced by fusion pressure
363
What happens to a sun-sized star after red giant stage?
It becomes a white dwarf, then a black dwarf
364
What is a supernova?
A huge explosion from a red supergiant
365
What can a supernova form?
A neutron star or a black hole
366
How are elements heavier than iron formed?
In supernovae
367
What does red-shift tell us?
Distant galaxies are moving away – universe is expanding
368
What does more red-shift mean?
The galaxy is moving away faster
369
What is Cosmic Microwave Background Radiation?
Low energy radiation left over from the Big Bang
370
What does CMBR support?
The Big Bang Theory
371
Why does orbital speed increase in lower orbits?
Stronger gravitational force
372
What type of orbit do communication satellites use?
Geostationary orbit (24-hour period)
373
What type of orbit do imaging satellites use?
Low polar orbit (frequent passes over Earth)
374
What is a black hole?
A very dense object with gravity so strong not even light can escape
375
The basic unit of living things
Define cell
376
What is a genome?
The entire genetic material of an organism
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379
Define current and state an equation that links current, charge and time, with units for each.
Current is the flow of electric charge. Equation: I = Q / t, where I = current (A), Q = charge (C), t = time (s).
380
What is meant by potential difference and resistance in a circuit?
Potential difference is energy transferred per coulomb of charge (V). Resistance is how much a component resists current (Ω).
381
Draw the circuit symbols for: a cell, a filament lamp, a diode, a fuse and an LDR.
[Diagram required – not included here]
382
What is the equation that links potential difference, current and resistance?
V = I × R, where V = potential difference (V), I = current (A), R = resistance (Ω).
383
Explain how you would investigate how the length of a wire affects its resistance.
Set up a circuit with variable wire lengths. Measure voltage and current, then calculate resistance using R = V / I.
384
What is an ohmic conductor?
A component where current is directly proportional to voltage, provided temperature is constant.
385
Draw a circuit that could be used to investigate how the resistance of a filament bulb changes with the current through it.
[Diagram required – not included here]
386
Name one linear component and one non-linear component.
Linear: resistor. Non-linear: filament bulb.
387
Explain how the resistance of an LDR varies with light intensity.
As light intensity increases, LDR resistance decreases.
388
What happens to the resistance of a thermistor as it gets hotter?
As temperature increases, thermistor resistance decreases.
389
True or false? Potential difference is shared between components in a series circuit.
True.
390
How does the current through each component vary in a series circuit?
It stays the same through all components.
391
How does potential difference vary between components connected in parallel?
Each branch gets the full potential difference.
392
Explain why adding resistors in parallel decreases the total resistance of a circuit, but adding them in series increases the total resistance.
Parallel resistors add more paths for current, lowering resistance. Series resistors increase total resistance.
393
Describe an experiment to investigate how adding resistors in series and parallel affects the total resistance of the circuit.
Build series and parallel circuits, measure voltage and current, then calculate resistance using R = V / I.
394
What is dynamic equilibrium?
Forward and reverse reactions at same rate, concentrations constant
