Yr 10 Valid Test

Question 1

Difference between CNS and PNS

Function of nervous system

Answer 1

The central nervous system (CNS) includes the brain and spinal cord, while the peripheral nervous system includes all of the nerves that branch out from the brain and spinal cord and extend to other parts of the body, including muscles and organs.
The nervous system helps all the parts of the body to communicate with each other. It also reacts to changes both outside and inside the body. The nervous system uses both electrical and chemical means to send and receive messages.

Question 2

How does the CNS operate?

Answer 2

receptors receive stimuli e.g., ears hear sounds, eyes see things, nose smells odours, skin feels heat and pain
• the stimuli are changed into electrical impulses and sent along sensory nerves to the brain
• the brain sends electrical stimuli along motor nerves to the muscles
• the muscles produce a response to the original stimulus e.g., the person runs from danger, blocks their ears from a loud sound, covers their eyes from a bright light

Question 3

Describe a disease of the nervous system

Answer 3

It’s considered an autoimmune disease in which the body’s immune system attacks its own tissues. In the case of MS , this immune system malfunction destroys the fatty substance that coats and protects nerve fibers in the brain and spinal cord (myelin).As a result, nerve impulses cannot travel properly between the brain and the rest of the body. These symptoms include sensory loss eg. loss of vision, loss of feeling, and motor loss eg. loss of movement, weakness in muscles.

Question 4

Purpose and process of endocrine system

Answer 4

The endocrine system controls activities in the body using hormones produced in glands. A stimulus is received by a receptor and then the hormones are carried by the blood to target organs where they are used to control growth, sexual development, body heat and levels of chemicals in the body such as glucose, water and salts.

Question 5

Explanation behind flight or fight response

Answer 5

The fight response involves both the nervous system and the endocrine system. This response can be initiated by shock, anger, passion, anxiety or stress. The nervous system detects fright stimuli, which are transmitted to the brain. The brain stimulates the pituitary gland to release hormones into the bloodstream. In particular, the adrenal glands above the kidneys react and release the hormone adrenalin into the blood. As a result, the pupils dilate, the skin becomes pale, the sense organs become highly sensitive, the heart beats faster, glucose is released into the blood, blood pressure increases and the lungs work more effectively. The body is now ready for action, either for fight or for flight.

Question 6

Purpose of immune system

Answer 6

The immune system protects the body against infectious diseases. When microorganisms such as bacteria and viruses invade the body, the immune system recognises them and produces antibodies that attack and destroy them

Question 7

Neutralisation reaction

Answer 7

acid + base → salt + water
hydrochloric acid + sodium hydroxide → sodium chloride + water
Examples
Bee stings contain acid and so they are treated with bicarbonate of soda because it contains a base
that neutralises the acid.
Wasp stings contain a base so they are treated with vinegar because it contains an acid that
neutralises the base.

Question 8

Acid and carbonate reaction

Acid and metal reaction

Answer 8

acid + carbonate → salt + water + carbon dioxide
Hydrochloric acid + sodium carbonate → sodium chloride + water + carbon dioxide
To test for carbon dioxide use Limewater (a solution of calcium hydroxide. So if we bubble carbon dioxide through the solution it reacts with calcium hydroxide solution to produce a white precipitate of calcium carbonate. We will observe that the limewater will turn milky or cloudy white).
acid + metal → salt + hydrogen
hydrochloric acid + magnesium → magnesium chloride + hydrogen
To test for hydrogen use pop test (bring a lit match to the mouth of the test tube containing the metal + acid, and if it makes a pop sound it contains hydrogen)

Question 9

Corrosion reaction
Combination reaction
Decomposition reaction

Answer 9

Acid + metal oxide → salt + water
Sulfuric acid + copper oxide → copper sulfate +water
Combination= x + y → xy
Decomposition= xy → x + y

Question 10

Define products and reactants

Answer 10

Products: A substance present at the end of a chemical reaction
Reactants: A substance that enters into and is altered in the course of a chemical reaction

Question 11

Define corrosion and galvanising

Answer 11

A natural process in which a refined metal is converted to a more chemically stable form, such as oxide, hydroxide, or sulphide.
The process of applying zinc coating to a more noble metal to prevent corrosion

Question 12

When is corrosion known as rusting

Answer 12

Rusting is the corrosion of iron

Question 13

Define electric current
Define conductor
Define insulator
Define resistor

Answer 13

The rate of movement of electric charges in a circuit.
A conductor is a substance that electric current flows through eg. metals, carbon. Conductors are used in electrical wiring to carry electric current to electrical appliances.
An insulator is a substance that electric current does not flow through eg. non-metals. Insulators are used to enclose electrical wiring and some electrical appliances to protect people from electrocution.
A resistor is a substance that electric current can flow through with difficulty and some of its electrical energy is changed into heat and light. They are used in appliances that produce heat and light eg. light globe, toaster, room heater, stove element.

Question 14

Define voltage
Define current
Define resistance

Answer 14

Voltage
Voltage is the difference in electrical potential between 2 points
As electric charges move through resistors they lose some of their electrical energy as it changes into heat and light. In an electric circuit, the voltage across a lamp or other resistor measures that amount of electrical energy that each electric charge loses as heat or light.
Voltage (V) is measured on a meter called a voltmeter in units called volts (V).
CURRENT
The number of electric charges that move in an electric circuit is called the current. When the current is large, eg 10A, more electric charges move around the electric circuit. When the current is small, eg 0.01A, fewer electric charges move around the electric circuit.
Current (I) is measured on a meter called an ammeter in units called amps (A).
RESISTANCE
Resistance is the limiting of electrical flow in a circuit. If the resistance is high, many of the electric charges have difficulty moving and lose some of their electrical energy as it changes to heat and light. If the resistance is low, the electric charges move easily and lose very little of their electrical energy.
Resistance (R) is measured in units called ohms (W).

Question 15

Define Ohms Law

Answer 15

A law stating that electric current is proportional to voltage and inversely proportional to resistance.
V
I R

Question 16

Evidence of evolution

Answer 16

Fossils show that the earliest life forms were simple organisms living in water and that since then organisms have become more complex and have moved onto land. Some fossils show links between groups of organisms. Archaeopteryx is a well known example of a transitional fossil. REPTILE features: long-tail, claws, solid bones, teeth
BIRD features: wish-bone, feathers, attaches for flight muscles on the sternum (breast bone).
The very young embryos of a number of vertebrates such as fish, salamander, turtle, chicken, pig, cow, rabbit and human look very similar and some scientists have concluded that the vertebrates have evolved from a common ancestor
Homologous structures indicate common ancestry, where different environmental pressures have led to different adaptations making them different species. For example, the pentadactyl limb is present in all groups of tetrapods and can be traced back to a pentadactyl ancestor that lived around 340 million years ago. In all tetrapods, the fundamental structures of the limbs are the same, implying a common ancestor, the differences brought upon by different environmental pressures.

Question 17

Define receptor
Define sensory nerve
Define motor nerve

Answer 17

A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific effect in the cell.
a nerve cell that detects and responds to external signals
a neuron that passes from the central nervous system or a ganglion toward a muscle and conducts an impulse that causes movement.

Question 18

Define gland
Define immune system
Define antibody

Answer 18

An organ which produces and releases substances that perform a specific function in the body
A complex network of cells, tissues, organs, and the substances they make that helps the body fight infections and other diseases.
A protein made by plasma cells (a type of white blood cell) in response to an antigen

Question 19

Define indicator
Define acidic
Define base
Define alkaline

Answer 19

A chemical that changes color when exposed to certain conditions and is therefore useful for chemical tests.
A substance which contains hydrogen and dissolves in water to produce one or more hydrogen ions
A substance that has a pH greater than 7 and has hydroxide or carbonate as part of their name.
A base that is soluble in water.

Question 20

Define ammonia
Define pH
Define neutralisation

Answer 20

colourless, pungent gas composed of nitrogen and hydrogen
a measure of how acidic/basic water is
when an acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water.

Question 21

Define circuit
Define series circuit
Define parallel circuit

Answer 21

A closed pathway for electrons to flow through.
A series circuit comprises a path along which the whole current flows through each component.
A parallel circuit comprises branches so that the current divides and only part of it flows through any branch.

Question 22

Define evolution

Define natural selection

Answer 22

Evolution is the permanent gradual change in the genetic composition of a population over long periods of time due to natural selection

The process by which individuals of a species that are better suited to their environment are more likely to survive and reproduce (while those not so well fitted to survive either die or fail to reproduce).

Question 23

Explain Darwin’s theory of evolution

Answer 23

• Far more offspring are produced than survive and reproduce.
• These offspring have a range of characteristics.
• Offspring with particular characteristics are better adapted to their environment and so survive
while other offspring perish. This is called natural selection or survival of the fittest.
• The surviving organisms reproduce and pass on the favourable characteristics to their offspring.
Over time the population changes so that most organisms have the favourable characteristics.

Question 24

Provide an example of evolution

Answer 24

Peppered moths are born either pale coloured or nearly black. In 1850, when scientists first began to study them, there were few factories and very little pollution. The countryside was fresh and clean and the pale coloured moths were well camouflaged when they rested on light coloured tree trunks. The black moths were easily seen and were quickly eaten by birds. The pale coloured moths were much better suited to their environment. They survived and reproduce and so were much more common than the black moths. In the years since 1850, more and more factories were built in northern England and the soot from the factory smokestacks gradually blackened the light coloured tree trunks. The change in the environment meant that the black moths were well camouflaged and birds ate the pale coloured moths instead. Scientists have determined that the body color in the peppered moth is controlled by a single gene. The allele (version of the gene) for dark body color is dominant, which means that a moth possessing at least one such allele will have a dark body. The black moths survived and reproduced and became much more common than the pale coloured moths. Strong anti-pollution laws over the past twenty years have reduced the amount of smoke coming from factories resulting in the tree trunks becoming lighter in colour. The pale coloured moths are once again well camouflaged and more black moths are being eaten by birds.

Question 25

Define fossils | Factors determining whether a fossil is made or not

Answer 25

Fossils are the remains, impressions or traces of living things QUICK BURIAL: The organism, its body parts (bones, shells) or its impression must be buried quickly so that it is not damaged by predators and so that it does not decay quickly. SUITABLE BODY PARTS: Hard body parts such as shells, bones and teeth form fossils but soft parts do not. UNDISTURBED ROCKS: Fossils form in sediments that are not disturbed by earth movements such as earthquakes and volcanoes. The sediments slowly harden into rocks and the fossils are kept intact.

Question 26

What is the law of superposition?

Answer 26

The Law of Superposition states that in a series of rock layers the oldest rocks are at the bottom and the youngest rocks are at the top.

Question 27

Importance of Geological Time scale

Answer 27

The Geological Time Scale shows when different types of plants and animals lived on earth. It divides the earth’s history into a number of periods. The first lifeforms were simple, aquatic organisms. Since then organisms have become larger and more complex and have moved onto land

Question 28

``` Define crest Define trough Define wavelength Define amplitude Define frequency ```

Answer 28

top of a wave bottom of a wave distance between two crests or two troughs distance between the crest and the rest position or the trough and the rest position the number of waves that pass a fixed point in unit time

Question 29

How to calculate wave speed | How are waves represented

Answer 29

Frequency X wavelength | Represented by a sine graph

Question 30

Define electromagnetic waves | What are they made of

Answer 30

waves that are created as a result of vibrations between an electric field and a magnetic field. Electromagnetic waves are composed of electric and magnetic fields and do not need particles to transfer energy, that is, they can travel through a vacuum.

Question 31

Electromagnetic waves purposes

Answer 31

radio waves: transmit radio and TV signals, radar in air traffic control microwaves: cooking, radar speed guns used by police infrared waves: given off by hot objects, used to take temperature pictures and find people in collapsed buildings visible: seeing, light: photosynthesis, photography UV rays: fluorescent lamps, sterilising X rays: radiography, treating cancer, finding faults in metals, examining crystals gamma rays: measure thickness of metals, sterilise medical equipment

Question 32

Absorption and reflection of colours in light

Answer 32

White light is made up of colours. When light hits a coloured object, that colour is reflected and all other colours in the light are absorbed by the object

Question 33

Relationship between wavelength and energy

Answer 33

The amount of energy is inversely proportional to the wavelength

Question 34

What is the Law of Reflection

Answer 34

On reflection from a smooth surface, the angle of the reflected ray is equal to the angle of the incident ray

Question 35

``` Define refraction Refraction instances Refraction in differing refractive indexes Define critical angle Define total internal reflection Define refractive index ```

Answer 35

The bending of a ray when it passes at an angle from one medium into another in which its speed is different Situations involving refraction: Any object in the water Rainbows Viewing something through glasses If light enters a substance with a lower refractive index (compared to previous substance) it will speed up and bend away from normal If light enters a substance with a higher refractive index (compared to previous substance) it will slow down and bend towards the normal When the angle of refraction is 90 degrees When light enters a medium at an angle greater than the critical angle, it is reflected, not refracted. Measure of optical density

Question 36

Difference between concave and convex

Answer 36

Concave: Faces inwards (think the caved in) Convex: Faces outwards

Question 37

Describe TIR in the process in optical fibres

Answer 37

Optical fibres are fibres made of glass through which light travels by a process called total internal reflection. As light travels through the glass fibres, it continually hits the sides which causes it to be reflected back into the glass rather than being refracted out. By repeated reflections, the light travels along the optical fibre

Question 38

Define cosmology | When did it begin?

Answer 38

The study of distant galaxies and the Universe is called cosmology. The invention of the telescope in the 16th century allowed galaxies to be viewed and studied a lot clearer than before, resulting in cosmology becoming another branch of science.

Question 39

Define astronomy | When did it begin?

Answer 39

Astronomy on the other hand is the study of the planets and stars and their movements, which began when ancient man first looked up at the night sky.

Question 40

Alternative explanation of universe creation. | Issue with explanation

Answer 40

Fred Hoyle (1949) hypothesized that the universe is never-ending and the same everywhere and for all time. The Universe, therefore, has no beginning and no end. As the universe expands new matter is created to keep the correct density at all times so that the universe does not change its look over time. Is no longer accepted as a possibility, because it cannot explain the presence of background microwave radiation in space.

Question 41

What is the Big Bang theory?

Answer 41

This theory states that all matter that existed came together in a core or one point, which exploded expanded outwards away from that core in a massive and violent explosion about 15 billion years ago. This ‘explosion’ resulted in dense and less dense areas being formed. The dense areas formed dense gas clouds leading to the formation of stars

Question 42

Evidence of big bang theory

Answer 42

This was actually the first evidence found that suggested the Big Bang might have happened. Edwin Hubble looked at lots of galaxies and discovered (using the Doppler effect / red shift) they were almost ALL moving away from the Milky Way (our galaxy) The only explanation was that they all used to be together once. If the universe was extremely hot at the beginning, there should still be some remnant of that heat today. 2 Scientists, Penzias and Wilson, found this Cosmic Microwave Background Radiation (CMBR) by accident in 1964. The universe has had a lot of time to cool, and if the big bang was 13.8 billion years ago, it should have cooled to around 3 degrees Kelvin (around -270°C). Guess what temperature Penzias and Wilson measured?

Question 43

Fates of the universe

Answer 43

Open Universe: the universe will keep expanding, becoming less and less active as the stars die, eventually dispersing in clouds of dust and gas. Flat Universe: The universe’s expansion will slow down and eventually stop at a maximum limit. Closed Universe: The universe’s expansion will slow, stop then start to contract and will collapse back on itself forming a dense mass, which will explode in a second Big Bang. This is affectionately termed the ‘Big Crunch’.

Question 44

How are stars created?

Answer 44

Stars are formed when nebulae collapse. The particles in these clouds attract each other resulting in an increase in their gravitational pull, therefore pulling in more particles. The temperature of this mass increases until it becomes high enough for nuclear fusion to take place.

Question 45

Relationship between mass and lifespan of a star | How is a red giant formed?

Answer 45

The mass of a star determines how long its life cycle will be. Larger stars will shine hotter and faster for much less than a smaller, cooler star. When a star’s fuel is used up, it starts to collapse. The core cools but the fusion process moves to the outer regions of the resulting in a colour change from white hot to red hot. The star is now a red giant, which is large but relatively cool.

Question 46

Life cycle of a star

Answer 46

Average star: stellar nebula, average star, red giant, planetary nebula, white dwarf Massive star: stellar nebula, massive star, red supergiant, supernova, neutron star or black hole

Question 47

Link between colour and temperature of a star

Answer 47

The colour of a star is linked to its temperature. Blue stars are the hottest with temperatures about 20 5000C, white stars are about 95000C and red stars are the coolest with temperatures less than 30000C. Our sun is a yellow star with a surface temperature of about 55000C.

Question 48

Layered structure of the earth

Answer 48

Crust, mantle, outer core, inner core

Question 49

Name of four spheres

Answer 49

Atmosphere – The envelope of gases surrounding the earth or another planet. Hydrosphere – The hydrosphere is the combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite. Lithosphere – the rigid outer part of the earth, consisting of the crust and upper mantle. Biosphere – The worldwide sum of all ecosystems.

Question 50

Explain the theory of continental drift

Answer 50

In 1915 Alfred Wegener proposed that all of the continents were once joined together into one vast land mass called Pangaea. About 250 million years ago, Pangaea broke into two parts. Laurasia consisted of North America, Europe and Asia. Gondwana (also called Gondwanaland), consisted of South America, Africa, Australia, Antarctica and India. About 200 million years ago, the continents gradually broke apart and separated. Since no explanation existed for its occurrence, it wasn't widely accepted.

Question 51

Evidence of continental drift

Answer 51

The shapes of the continents fit together like the pieces of a jigsaw. Eroded mountain ranges, patterns of scouring by glaciers and deposits of iron ore all match up on different continents Similar limestone deposits are found in Australia, Antarctica and southern Africa. Glossopteris fossils remains in similar rock layers all formed in Antarctica, Australia, South America, Africa and India which lived in wet swampy regions Mesosaurus remains being found in South America and Africa even though freshwater lakes and ponds don't exist in Africa Scratches from glaciers found in central tropical Africa… Fossils of palm trees found in frozen Alaska Fossils younger than 150 million years are different on all continents.

Question 52

Evidence of crust formation

Answer 52

The basalt rock underlying the ocean is youngest at the ridge and gets older the further it is away from the ridge. Mid-ocean sediments are thinnest at the ridge and are thicker further away from the ridge.

Question 53

How is earth's crust created? | Effects from tectonic plate movement

Answer 53

At mid-oceanic ridges, molten rock rises up from the asthenosphere, cools to form solid rock and pushes the plates outwards. This produces new crust. • At other plate boundaries, plates collide and produce earthquakes along with either volcanoes or fold mountains. • At a third type of plate boundary, two plates slide past each other. The grinding action causes earthquakes, eg. movements along the San Andreas fault in California has produced earthquakes in San Francisco.

Question 54

Cause of tectonic plate movement

Answer 54

Convection currents drive the movement of Earth’s rigid tectonic plates in the planet’s fluid molten mantle. In places where convection currents rise up towards the crust’s surface, tectonic plates move away from each other in a process known as seafloor spreading (Fig. 7.21). Hot magma rises to the crust’s surface, cracks develop in the ocean floor, and the magma pushes up and out to form mid-ocean ridges. Mid-ocean ridges or spreading centers are fault lines where two tectonic plates are moving away from each other.

Question 55

``` Define hypocentre (focus of an earthquake) Define epicentre What do the seismic waves carry? ```

Answer 55

The hypocenter is the point within the earth where an earthquake rupture starts. The epicentre is the place on the Earth’s surface that is closest to the focus of the earthquake. Energy is carried out from earthquakes by seismic waves.

Question 56

Define correlation (geology) Define plate tectonics Define convection currents

Answer 56

The technique of piecing together information from widely separated rock outcrops in order to create an accurate chronological profile of an entire geologic time period. Scientific theory explaining how major landforms are created as a result of Earth's subterranean movements. When particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy

Question 57

Difference between Reliability Accuracy Validity

Answer 57

The extent to which the findings of repeated experiments, conducted under identical or similar conditions, agree with each other. The extent to which a measured value agrees with its true value The extent to which an experiment addresses the question under investigation.

Question 58

``` Define hypothesis scientific law scientific theory scientific method ```

Answer 58

A suggested explanation for an observation that is followed with experimentation. A basic fact that describes the behaviour of a natural phenomenon. An explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method The process of objectively establishing facts through testing and experimentation.

Question 59

Can theories be removed? | How are scientific laws formed?

Answer 59

If the results of subsequent experiments disprove a theory, the theory can be replaced by a newer theory. Over a long period of time, a scientific theory may become a scientific law if no experiments have been able to disprove it.

Question 60

Difference between a reliable and valid experiment

Answer 60

A reliable experiment repeats the method numerous times and obtains similar results. A valid experiment is reliable plus tests the independent variable and controls all other variables.

Question 61

How is information regarding the experiment collected? | What type of observations are preferred in experiments?

Answer 61

Scientists collect information from experiments by making observations using their senses and measuring instruments Where possible, scientists make quantitative observations because they are more accurate.

Question 62

Structure of an atom

Answer 62

An atom is the smallest particle of matter. It contains • protons - positive subatomic particles found in nucleus of atom • neutrons - neutral subatomic particles found in nucleus of atom • electrons - negative subatomic particles that orbit the nucleus of an atom

Question 63

No of elements

Answer 63

There are more than 110 known elements

Question 64

Arrangement of periodic table of elements

Answer 64

The elements are arranged in the Periodic Table in order of increasing atomic number. The horizontal rows are called periods. The vertical columns in the Periodic Table are called groups and elements in the same group have similar properties.

Question 65

Groups in periodic table

Answer 65

Group 1 elements (Li, Na, K) are called the alkali metals. They are all metals and solids at room temperature. They all have one electron in the outer electron orbit and form ions with a charge of +1. They react with water. • Group 2 elements (Be, Mg, Ca) are called the alkaline earth metals. They are all metals and are solids at room temperature. They all have two electrons in the outer electron orbit and form ions with a charge of +2. They react with acid. • Group 7 elements (F, Cl, Br, I) are called the halogens. They are all metals and are solids, liquids and gases at room temperature. They form ions with a charge of –1. • Group 8 elements (He, Ne, Ar) are called the inert gases or noble gases. They are all non-metals and are gases at room temperature. They have a full outer electron orbit and so do not react with other elements.

Question 66

Define precipitate reactions

Answer 66

In a precipitation reaction, two solutions are mixed together to produce an insoluble solid called a precipitate copper + sodium →copper + sodium sulfate hydroxide hydroxide. sulfate Copper hydroxide is insoluble in water and so it is the precipitate.

Question 67

Distance speed time triangle

Answer 67

The distance travelled by an object is equal to its average speed multiplied by the time it takes to travel the distance. d v t

Question 68

Purpose of time graphs

Answer 68

time graphs show the distance travelled by a person or object as time passes. The slope of the line in any section of the graph is the speed of the person or object in that period of time.

Question 69

Define velocity Symbol for velocity Si unit for velocity

Answer 69

A measurement of an objects motion and the direction of its motion. v m/s or ms^-1

Question 70

velocity, displacement, time triangle

Answer 70

s | v. t

Question 71

Define acceleration and deceleration Symbol for acceleration Si unit for acceleration Formula

Answer 71

The rate at which velocity changes over time, due to either change in speed or change in direction The rate at which velocity decreases over time. a m/s/s or m/s^2 or ms^-2 Change in velocity/change in time

Question 72

Define inertia

Answer 72

Inertia is the tendency of an object to stay at rest or keep moving at the same speed in the same direction.

Question 73

Newton's first law of motion Newton's second law of motion Newton's third law of motion

Answer 73

An object at rest will remain at rest, unless an unbalanced force acts on it, and an object in motion will remain in motion unless an unbalanced force acts on it. A force applied to an object will accelerate it proportional to the force, and inversely proportional to its mass F=ma For every action (force) there is an equal and opposite reaction (force)

Question 74

Technological advancements in cars relating to newtons laws of motion

Answer 74

Cars have technology to oppose inertia and so protect passengers from injury and death. For example, when a car stops suddenly, the seat belt stops the passenger from moving forwards. In cases where the passenger moves forwards, the air bag stops them from hitting the windscreen or steering wheel. A head restraint works in the opposite way. When a car is hit from behind, the head restraint stops the passenger’s head from moving backwards.

Question 75

Examples of third law of motion

Answer 75

For example, when a gun fires a bullet, it pushes the bullet forwards. The bullet then pushes backwards on the gun with the same force. The burning fuel in a rocket engine pushes hot exhaust gases out of the rocket. As this happens, the gases push on the inside of the rocket forcing it upwards.

Question 76

Define gravity Define mass Define weight

Answer 76

The force of attraction between all masses in the universe The amount of matter in an object The force of gravity pulling down on the object. It is measured in Newtons (N) on a spring balance.

Question 77

Define chromosome

Answer 77

A thread-like structure found in the nucleus of all cells (except red blood cells), where DNA is packaged up in sections to protect it. Human cells contain 46 chromosomes that exist as 23 pairs. The X and Y chromosomes are called the sex chromosomes because they determine the sex of an individual. XX = female and XY = male.Chromosomes are made of DNA (deoxyribonucleic acid) which has a double helix structure, that is, it looks like a twisted ladder.

Question 78

Define gene

Answer 78

The basic unit of heredity passed from parent to child. Genes are located on chromosomes and carry the information that determines an individual’s characteristics. Children inherit 23 chromosomes from each parent which means that they receive half of their genes from each parent and so resemble each of their parents in some ways. Environmental factors also have some effect in determining the characteristics of an individual.

Question 79

Define DNA

Answer 79

Deoxyribonucleic acid; a molecule that contains the biological instructions that make each species unique. DNA contains two strands of sugars and phosphates joined along their length by pairs of bases. The base pairs are adenine-thymine (A-T) and cytosine-guanine (C-G).

Question 80

Purpose of cell replication

Answer 80

Cells divide to produce new cells for growth, repair and reproduction. Before they divide, their DNA must be replicated (copied) exactly so that the new cells receive the correct DNA which means that normal growth, repair and reproduction will occur.

Question 81

Define mutation

Answer 81

A mutation is a change in a gene and it occurs when DNA is not replicated exactly. Some mutations are an advantage eg, a mutation in a wild variety of grape produced the Concord grape which is larger and sweeter than other grapes. Other mutations are a disadvantage eg, the disease cystic fibrosis comes from a gene mutation and it causes abnormal cell function that produces excess mucus in the lungs and digestive tract.

Question 82

Define biotechnology

Answer 82

The use of biology to solve problems and make useful products.Some examples of biotechnology are using yeast to make alcohol, using bacteria to clean up oil spills, using bacteria to produce human insulin, cloning, stem cell therapy, DNA fingerprinting.

Question 83

Define genetic engineering

Answer 83

Genetic engineering is a type of biotechnology that changes genes. It involves inserting genes from one species into the chromosomes of another species. The recipient of the inserted genes is called a transgenic organism.

Question 84

Uses of genetic engineering

Answer 84

One use of genetic engineering in medicine is the production of human insulin by bacteria. The gene for human insulin is inserted into bacteria and then the bacteria make human insulin. The insulin is collected and given to diabetics. The benefits are that it provides an unlimited supply of insulin and many diabetics are not allergic to it. One use of genetic engineering in agriculture is the protection of cotton plants from caterpillars. The Bt bacterium contains a gene that produces a protein that kills caterpillars. This gene is inserted into the cells of cotton plants so that the plants make the protein. When the caterpillar eats the plant, it takes in the protein and dies. Two benefits are that farmers use less pesticide sprays and they get a higher yield of cotton.

Question 85

Define GM crops | Pros and cons of gm crops

Answer 85

Foods derived from organisms whose genetic material (DNA) has been modified in a way that does not occur naturally. GM crops have been inserted with a gene that makes them superior to conventional crops, such as crops that are higher quality, disease resistant, grow in poor soils, have a higher yield, have a shorted growing period. All of these benefits produce a larger, better quality crop harvest which results in a higher profit for farmers. The use of GM crops however is causing concern because of their unknown long term impact on ecosystems. For example, crops with inbuilt pesticides kill insect pests that eat them but they might also kill insects that are not pests. As a result, this would threaten damage to all organisms in the food web.

Question 86

The appearance of an organism is the result of two factors?

Answer 86

the gene being expressed | the environment

Question 87

How are traits inherited

Answer 87

There are 3 different ways in which traits can be inherited • dominant or recessive traits • co-dominant traits • incomplete dominant traits.

Question 88

Define incomplete dominance | Define co-dominance

Answer 88

In some organisms when both alleles are present, the organism will display an intermediate appearance which is often a combination of both parent phenotypes. In some organisms when both alleles are present, the organism will display both the characteristics in separate, distinguishable ways.

Question 89

Comparison between meiosis and mitosis

Answer 89

Similarities: both possess the basic 5 phases, same number of chromosomes as the original cell and cell division can occur Differences (mitosis): divided from somatic cell, 2 daughter cells, all daughter cells have 46 chromosomes and 5 phases occur Differences (meiosis): divided from reproductive cell, 4 daughter cells, all daughter cells have 23 chromosomes and 9 phases occur

Question 90

Importance of: water cycle carbon-oxygen cycle nitrogen cycle

Answer 90

ensures continual supplies of fresh water for plants and animals. ensures continual supplies of carbon dioxide for photosynthesis by plants and oxygen for respiration by plants and animals. ensures continual supplies of nitrogen in the form of nitrates in the soil for use by plants and then animals as they eat plants

Question 91

``` Define environment Define habitat Define biodiversity Define abiotic Define biotic ```

Answer 91

environment – all the things that surround and affect an organism in its life habitat – the place in an environment where a plant or animal lives biodiversity – the variety of organisms in an environment abiotic – physical factors biotic – biological factors

Question 92

Food chain vs food web

Answer 92

While a food chain follows a singular path of energy from a producer to a top predator, food webs illustrate the ways different animals are interconnected and interact in a food chain.

Question 93

Why introduced species are detrimental

Answer 93

The introduction of animals and plants into Australia since European settlement has had devastating impacts on ecosystems. The rabbit was introduced into Victoria in the mid 1800s. The small population reproduced very quickly and spread rapidly into other states. The large numbers of rabbits stripped the land bare of grass and dug burrows over much of the land. As a result, some small native mammals, such as the bilby, were forced to compete with the rabbit for food and space and the consequences were disastrous. The lack of food and space caused large numbers of native animals to perish while surviving animals were pushed into harsher environments. The flourishing rabbit population also led to a rise in the fox and feral cat populations, both of which preyed on numerous native animals. All of these factors resulted in a severe decrease in the reproduction of native animals and survival of their offspring, leading to a rapid decline. Ultimately, numerous native species became endangered or extinct.

Question 94

Define combustion

Answer 94

An exothermic reaction in which a fuel reacts with oxygen to release energy detected as heat and light Combustion(burning) always have oxygen as a reactant and water and carbon dioxide as products. Combustion reactions are exothermic (both heat and light are produced). fuel + oxygen → carbon dioxide + water

Question 95

Define radioisotopes | types of radioactive radiation

Answer 95

An unstable form of a chemical element that releases radiation as it breaks down and becomes more stable. There are three types of radioactive radiation: Gamma rays – high frequency, high energy electromagnetic waves that are the most penetrating and most dangerous type of radiation. This energy is also called nuclear energy as it comes form the nucleus of atoms. Beta particles – fast moving streams of electrons Alpha particles – positively charged helium nuclei that are the least penetrating type of radiation.

Question 96

Define half-life

Answer 96

The half-life of a radioisotope is the time taken for half of the atoms to radioactively decay. Some radioisotopes such as uranium are dangerous because they have a long half-life which means that they emit radiation for a long period of time.

Question 97

dangers of radioisotopes

Answer 97

Exposure to very high levels of radiation, such as being close to an atomic blast, can cause acute health effects such as skin burns and acute radiation syndrome (“radiation sickness"). It can also result in long-term health effects such as cancer and cardiovascular disease.

Question 98

Application of radioisotopes

Answer 98

Medicine: Cobalt 16 is used to kill cancer cells without surgery. Iodine 131 is injected into thyroids to detect malfunction or thyroid glands Agriculture: Metabolism of phosphorus in plants can be studied using phosphorus fertilises containing phosphorus 32 Archaeology: Carbon 14 is used to detect the age of fossils Industries: A particle from polonium 210 is used to neutralise static charge in photographic plates

Question 99

Structure of endocrine system | Function of endocrine system

Answer 99

Many glands make up the endocrine system. The hypothalamus is at the middle of the brain, pituitary gland is at the bottom right of the brain, and pineal gland is at the top left of the brain. The parathyroid is at the top and the thyroid glands is at the bottom of your neck. The thymus is between your lungs, the adrenals are on top of your kidneys, and the pancreas is behind your stomach. The endocrine system, made up of all the body's different hormones, regulates all biological processes in the body from conception through adulthood and into old age, including the development of the brain and nervous system, the growth and function of the reproductive system, as well as the metabolism and blood sugar levels.

Question 100

Non-infectious disease in endocrine system and effects in the body Role of a hormone in the body

Answer 100

Diabetes causes heart and blood vessel disease. Diabetes is associated with an increased risk of heart disease, stroke, high blood pressure and narrowing of blood vessels (atherosclerosis). Adrenaline triggers the body's fight-or-flight response. This reaction causes air passages to dilate to provide the muscles with the oxygen they need to either fight danger or flee. Adrenaline also triggers the blood vessels to contract to re-direct blood toward major muscle groups, including the heart and lungs.

Question 101

Immune system response to diseases

Answer 101

Lymphocytes are a type of white blood cell. There are B and T type lymphocytes. B lymphocytes become cells that produce antibodies. Antibodies attach to a specific antigen and make it easier for the immune cells to destroy the antigen. T lymphocytes attack antigens directly and help control the immune response. As lymphocytes develop, they normally learn to tell the difference between your own body tissues and substances that are not normally found in your body. Once B cells and T cells are formed, a few of those cells will multiply and provide "memory" for your immune system. This allows your immune system to respond faster and more efficiently the next time you are exposed to the same antigen. In many cases, it will prevent you from getting sick. For example, a person who has had chickenpox or has been immunised against chickenpox is immune from getting chickenpox again.

Question 102

Chemical formulas for hydrochloric acid, sulfuric acid, sodium hydroxide, ammonia, sodium chloride

Answer 102

``` HCl, H₂SO₄ NaOH NH3 NaCl ```

Question 103

Why do components in an electric circuit have resistance?

Answer 103

An electric current flows when electrons move through a conductor, such as a metal wire. The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance.

Question 104

Define catalyst | Relationship between surface area and rate of reaction

Answer 104

Catalyst: chemicals which increases the rate of a reaction without being used up itself. Higher surface area increases exposed particle's chance to react consequently increasing frequency of particle collision therefore increasing rate of reaction

Question 105

Concept of collision theory

Answer 105

that reactant particles must collide with each other, that particles must have enough energy for them to react and that they must collide with the correct orientation.

Question 106

Relationship between concentration of reactants and rate of reaction Relationship between temperature and rate of reaction

Answer 106

An increase in the concentration of reactants increases the rate of reaction as they are a greater number of particles to react consequently increasing the frequency of collisions. An increase in temperature increases the kinetic energy of particles consequently increasing the frequency of particle collisions and a greater proportion of collisions will possess the energy to react.

Question 107

Relationship between pressure of reaction in gases and rate of reaction Relationship between catalyst and rate of reaction

Answer 107

Increasing the pressure of a reaction involving gases forces the gas particles closer. This will increase the frequency of particle collisions, and therefore increase the rate of reaction. A catalyst provides an alternative route for the reaction with a lower activation energy. This means that particle collisions need less energy in order for a reaction to occur, increasing the rate of reaction.

Question 108

Define effector Define reflex action Process of reflex action

Answer 108

Parts of the body that produce a response to a detected stimulus. A reflex action is an automatic (involuntary) and rapid response to a stimulus, which minimises any damage to the body from potentially harmful conditions, such as touching something hot.The electrical impulse travels along the sensory nerve and then passes directly to the motor nerve rather than to the brain. It is usually a response to danger eg, when you touch a hot object you pull your hand away very quickly without it.

Question 109

Define carbonate Define anion Define cation Define ganglia

Answer 109

An ion consisting of one carbon and three oxygen atoms or a compound that contains this species as its anion a negatively charged ion a positively charged ion Ganglia are clustered nerve cells located in the PNS

Question 110

Define endocrine Define hormone Define enzyme

Answer 110

The glands and organs that make hormones and release them directly into the blood so they can travel to tissues and organs all over the body. chemical substances that act like messenger molecules in the body. A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction

Question 111

Define exothermic Equation for photosynthesis Equation for respiration

Answer 111

Reactions in which heat energy is released from the reaction to the surroundings Sunlight + carbon dioxide + water → glucose + oxygen Glucose + oxygen → carbon dioxide + water + energy

Question 112

Define respiration

Answer 112

An exothermic reaction which takes place in living cells in which energy is released from a reaction between glucose and oxygen and does not require an external source of heat

Question 113

Define digestion | Types of digestion

Answer 113

The process in which nutrients and energy are extracted from the food we eat so that it can be in a form that can be absorbed by the body’s cells. The two types are: Mechanical digestion which occurs in the mouth when food is physically broken down or mashed into smaller pieces (without enzymes). Chemical digestion, which occurs at various stages along the alimentary canal, when special chemicals called enzymes chemically breakdown food.

Question 114

Where are bile salts made? Where do bile salts works? Substrate (what bile salts acts on) Products

Answer 114

Liver Small intestine Fat Fat products

Question 115

Define spontaneous combustion Define rapid combustion Define explosion

Answer 115

The combustion in which substances starts burning suddenly even without being heated e.g. sodium and phosphorus burn spontaneously in air, even when no external heat is provided to them. The combustion in which substances burn rapidly to produce heat and light is called rapid combustion. In rapid combustion,external heat must be supplied so that the substances can burn. E.g. oil lamp, burns rapidly to produce heat and light when they come in contact with fire. A combustion reaction that occurs suddenly when a material is heated, liberating a large amount of gas and producing heat, light and sound

Question 116

Define surface area Define temperature Define chemical energy

Answer 116

The measure of how much exposed area a solid object has, usually expressed in square units such as metres squared (m2) or square centimetres (cm2). A measurement of the warmth or coldness of an object Energy stored in the chemical bonds between atoms in a molecule. It can be released when chemicals break apart (eg burning) or absorbed when they are joined (eg photosynthesis)

Question 117

Describe the process of an exothermic reaction

Answer 117

Reactions that release energy are called exothermic reactions. In an exothermic reaction, the products have less stored energy than the reactants at the start of the reaction. The thermal energy produced in an exothermic reaction comes from the chemical energy stored in the bonds between the atoms of the reactants. When these bonds break, the energy is released and goes into the surroundings, usually causing the temperature to rise.

Question 118

Describe the process of an endothermic reaction

Answer 118

Chemical reactions that absorb energy are called endothermic. In an endothermic reaction, energy is taken from the surroundings and the products have more energy than the reactants. Since energy is being removed from the surroundings, endothermic reactions will often cause the temperature of the surroundings to drop.

Question 119

Application of endothermic reactions

Answer 119

An application of endothermic reactions include cold packs. Cold packs reduce swellings and numb pain caused by injuries. They usually contain ammonium nitrate, which undergoes an endothermic reaction when the inner bag is broken. This allows the salt to dissolve in water,absorbing the thermal energy of the water in the process. This cools the water and makes the bag feel cold.

Question 120

Application of exothermic reactions

Answer 120

No heat is not needed to burn coal , rather burning coal produces heat. But for the burning reaction to start it needs a small boost of energy(activation energy) to start; once started it sustains itself and continues to produce heat up to the end. That is why it is called exothermic

Question 121

How is a chemical bond formed and broken

Answer 121

To form the chemical bond, energy from reaction is released to the surrounding resulting increase of temperature of surrounding. To break the chemical bond, energy from surrounding is absorbed resulting decrease of temperature of surrounding.

Question 122

How does fossilisation occur?

Answer 122

An organism dies and is quickly covered by sediment. Over time, the sediment turns into rock. The remains of the organism turn into a fossil. The fossil is flattened by layers of rock. The rock is folded and eroded and the fossil can be seen on the surface.

Question 123

Mnemonic for waves in em spectrum

Answer 123

``` Red Mice Invade Voracious Ultraviolet X-ray Goats ```

Question 124

Define reproduction Define characteristic Define adaptation Define species

Answer 124

The biological process by which new individual organisms offspring are produced from their parents Feature defined by a standard of points or identified features Any feature of a living organism that makes it better able to survive in its environment. A group of organisms that are able to reproduce together, making offspring that can also reproduce.

Question 125

``` Define chemical formula Define atom Define element Define molecule Define compound ```

Answer 125

A set of chemical symbols showing the elements present in a compound and how many there are for each element in the form of subscripts. The smallest particle of an element that has all of the chemical properties of that element. An element is a substance that is made of only one type of atom; it cannot be decomposed. It is represented by a single shape or two of the same shape joined together. Two or more atoms that are joined by a chemical bond. A chemical substance formed from two or more elements, with a fixed ratio determining the composition

Question 126

Difference between transverse and longitudinal waves Define neuron Define pathogen Define ecology

Answer 126

Transverse waves cause the medium to move perpendicular to the direction of the wave. Longitudinal waves cause the medium to move parallel to the direction of the wave. A long thin cell that transmits messages in the body, also known as a nerve cell Microbes that cause diseases are called pathogens Study of the relations of organisms to one another and to their surroundings.

Question 127

Define sphere interactions Define isotope Define radioactive

Answer 127

The processes that move matter and energy from one sphere to another are called sphere interactions. Atoms of the same element that have same number of protons but different number of neutrons. A substance containing unstable atoms, which can spontaneously decay (break down) and emit nuclear radiation, either alpha or beta particles or gamma rays.

Question 128

Different types of boundaries

Answer 128

Transform: This is a plate boundary where two plates move horizontally, in the opposite direction. Divergent: This is a plate boundary where two plates move away from each other. Convergent: This is a plate boundary where two plates move closer together.

Question 129

Define doppler effect Define nebulae Define electromagnetic spectrum Define space probe

Answer 129

An change in the frequency of waves as the source and observer move towards (or away from) each other. Large clouds of gas and dust in space, which either form the raw material for new stars, or are produced when a star explodes. The range of wavelengths or frequencies over which electromagnetic radiation extends. A probe is a spacecraft that travels through space to collect scientific information. Probes do not have astronauts.

Question 130

Define salt

Answer 130

any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation