Additional Science (Route 2): Unit 5 Flashcards
Draw and label a human cell
What are the functions of these parts of a cell?
Nucleus
Cytoplasm
Cell membrane
Nucleus – contains DNA and controls the activities of the cell
Cytoplasm – where most of the chemical reactions occur
Cell membrane – controls the passage of substances in and out of the cell
What are the functions of these parts of a cell?
Mitochondria
Ribosomes
Mitochondria – where energy is released from respiration
Ribosomes – where protein synthesis occurs
Draw and label a plant cell
What are the functions of these parts of a cell?
Cell wall
Chloroplasts
Permanent vacuole
Cell wall – strengthens the cell
Chloroplasts – absorb light energy to make food via photosynthesis
Vacuole – filled with cell sap and provides a store of water
What do the vacuoles of plant cells contain?
Cell sap
What controls the chemical reactions inside cells?
Enzymes
What is diffusion and where does it happen?
Diffusion is the net spreading out of particles of a gas (or substance in a solution) from [high] to [low]
Diffusion occurs in the lungs – this is how oxygen is moves into the blood
What affects the rate of diffusion?
Temperature and the [concentration] difference effects the rate of diffusion
What is osmosis and where does it occur?
Water often moves via osmosis – the water particles move from a net [high] to a [low] across a partially permeable membrane
Osmosis occurs in the root hair cells
What happens to a plant cell if you put it in highly salty water?
In salty water there is a [low] of water – this means water moves out of the cell (from [high] to [low]) and the cell will shrink and become flaccid
What happens to a plant cell if you put it in pure water?
In pure water there is a [high] of water resulting in water moving into the cell (from [high] to [low]) and the cell will fill of water and become turgid
Draw a picture of a red blood cell and explain how it is specialised
Draw a picture of a nerve cell and explain how it is specialised
Draw a picture of a cilia cell and explain how it is specialised
Draw a picture of a root hair cell and explain how it is specialised
Draw a picture of a guard cell and explain how it is specialised
Draw a picture of villi in the small intestine and explain how it is specialised
What is the equation for photosynthesis?
Light
6CO2 + 6H2O → C6H12O6 + 602
Why is energy needed for photosynthesis and how does a plant obtain this energy?
Energy is needed to convert carbon dioxide and water into sugar (glucose)
The energy is light energy – this is trapped by the chlorophyll in the chloroplasts
What can affect the rate of photosynthesis?
Temperature
Carbon dioxide levels
Light intensity
What is a limiting factor and what can these be in photosynthesis?
A limiting factor is anything, which prevents a process from continuing to increase
In photosynthesis there are: -
Low temperature
Shortage of CO2
Shortage of light
What is the glucose produced by photosynthesis used for?
Used for respiration
Stored as starch
How do plants store glucose?
Insoluble starch
What minerals do plants need for healthy growth?
Nitrates and magnesium are needed for healthy growth of a plant
Why do plants need nitrates and magnesium?
Nitrates – needed to produce amino acids (used to form proteins)
Magnesium – for chlorophyll production
How can you tell if a plant is deficient in the following?
Nitrates
Magnesium
Nitrates – stunted growth (no proteins)
Magnesium – yellow leaves (no chlorophyll)
What is the energy source for most communities of living organisms?
Radiation from the Sun
What do plants compete for?
What do animals compete for?
Plants – light; water; nutrients (from soil)
Animals – food; mates; territory
Where is DNA carried in most cells?
In the nucleus
What is a quadrat and how is it used?
A quadrat is a square frame enclosing a known area (e.g. 1m2) to measure the numbers of organisms in an area
What are transects and how are they used?
Transects are lines to identify how distributed across an area an organism is
*Collect data along line / use quadrats
What are bacteria?
Bacteria are single-celled microorganisms (which lack a nucleus)
What are yeast?
Yeast are single celled organisms
What are tissues, organs and organ systems?
Similar cells are organized into tissues (cells which work together to complete a certain function)
Organs are a group of different tissues working to perform a function
Organ systems are organs which work together to complete a function
What are the main parts of the digestive system?
Draw and label an atom
What are the masses and charges of these parts of an atom?
Proton
Neutron
Electron
Protons = +ve
(mass 1)
Neutrons = neutral
(mass 1)
Electrons = -ve
(mass 1/2000th)
Why do atoms usually have no overall electrical charge?
Atoms usually have no overall charge because they have equal numbers of protons (+ve) and electrons (-ve), which cancel one another out
All atoms of a particular element (e.g. carbon) all have the same number of what?
Protons
What are the following numbers called?
a = relative atomic mass
b = atomic number
What do the numbers tell you about the atom?
a = relative atomic mass – the number of protons and neutrons in the atom
b = atomic number – the number of protons (usually the same as the number of electrons)
What is an alloy and why are they used?
Give some examples
Alloys are mixtures of metals with other elements, e.g. iron + carbon → steel
They have a combination of properties, e.g. bronze, brass, steel etc…
What is a smart alloy and why are they used (shape-memory)?
Give some examples
Smart alloys can return to their original shape after being deformed – e.g. glasses and braces
What do these terms means: -
Element
Compound
Mixture
Element – pure substance with only 1 type of atom (e.g. gold)
Compound – 2 or more elements chemically bound (e.g. carbon dioxide)
Mixture – more than 1 element or compound not chemically bound (e.g. air)
What are the symbols for the following atoms: -
Oxygen, Nitrogen, Chlorine, Hydrogen, Sodium, Copper, Potassium, Helium, Calcium, Zinc, Iron, and Carbon
Oxygen (O), Nitrogen (N), Chlorine (Cl), Hydrogen (H), Sodium (Na),
Copper (Cu), Potassium (K), Helium (He), Calcium (Ca), Zinc (Zn), Iron (Fe), and
Carbon (C)
What happens to atoms when they chemically react to form a compound?
They share, give away, or take electrons
What are the names of these compounds, and which atoms are found in them?
H2O
CaCO3
H2SO4
HCl
CO2
Water (H2O)
Calcium carbonate (CaCO3)
Sulfuric acid (H2SO4)
Hydrochloric acid (HCl)
Carbon dioxide (CO2)
What is an isotope?
An isotope is an atom with a different amount of neutrons
Use the periodic table to draw the electron structure of the following: -
Neon
Calcium
Sodium
How can you tell which group these atoms are in?
The number of electrons in the outer shell is the same as their group number
How many electrons can occupy the 1st and 2nd shell (energy level) of an atom?
2 in the 1st shell and 8 in the 2nd shell
The electron structure of sodium can be represented as 2,8,1 – what does this mean?
Represent these atoms: -
Fluorine
Oxygen
Potassium
Magnesium
2,8,1 means 2 electrons in the 1st shell, 8 electrons in the 2nd shell and 1 electron in the 3rd shell
Fluorine = 2,7
Oxygen = 2,6
Potassium = 2,8,8,1
Magnesium = 2,8,2
Define these terms: -
Element
Compound
Mixture
Element – a pure substance made from 1 type of atom only
Compound – 2 or more elements chemically bound
Mixture – 2 or more elements or compounds mixed together which are not chemically bound
What happens to the electrons of 2 atoms when they chemically react?
During a chemical reaction electrons are either given away, taken, or shared
What is an ion?
How are +ve ions formed?
How are -ve ions formed?
An ion is an atom with a charge
+ve ions have lost electrons
-ve ions have gained electrons
Explain how the following atoms become ions (will they be +ve or –ve)?
Potassium
Magnesium
Chlorine
Oxygen
Potassium – loses 1 electron (K+)
Magnesium – loses 2 electrons (Mg2+)
Chlorine – gains 1 electron (Cl-)
Oxygen – gains 2 electrons (O2-)
Use diagrams to show how these atoms for ionic bonds: -
Sodium + Chlorine
Describe and use a diagram to show the structure of ionic compounds
Ionic compounds have a giant structure – they are bonded to 6 other ions by electrostatic bonds
What are the melting and boiling points of ionic compounds like?
Why is this?
Ionic compounds have high melting points and boiling points – to melt them you have to supply enough energy to break the 6 bonds attached to each ion
What happens to the electrons when atoms form ionic bonds and covalent bonds?
Which is the strongest?
Ionic bonds – 1 atom loses electrons and another gains electrons
Covalent bonds – electrons are shared
An individual covalent bond is stronger than an ionic bond
Use diagrams to show how the following compounds are formed: -
Hydrogen
Oxygen
Hydrogen Chloride
Use a diagram to show how water is formed
What are the melting and boiling points of covalent compounds like?
Explain why this is
Covalent compounds have low melting and boiling points (are often gases) are there is no attraction between the molecules
How are the elements of the periodic table arranged?
What are the rows called?
What are the columns called?
Elements are arranged in order of atomic number
Rows are called periods
Columns are called groups
Which 2 elements would be out of order in the periodic table if they were arranged by atomic mass instead of atomic number?
Potassium and Argon
Why do elements in the same group have similar properties?
Elements in the same group have similar properties as they all have the same number of electrons in their outer shell
What do these symbols mean?
(s)
(l)
(g)
(aq)
(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous
What are the symbols for these compounds?
Calcium carbonate
Sodium chloride
Hydrochloric acid
Calcium carbonate – CaCO3
Sodium chloride – NaCl
Hydrochloric acid - HCl
Why do covalent compounds not conduct electricity when dissolved?
Covalent compounds do not conduct because they do no break down into ions
Give the names of 3 covalent compounds which have giant ionic structures?
What is the structure of each like?
Diamond – 4 carbon-carbon covalent bonds
Graphite – 3 carbon-carbon covalent bonds
Silicon dioxide – 2 double silicon-oxygen covalent bonds
Why does graphite conduct electricity?
Graphite conducts electricity because it is only bonded 3x (meaning there is a delocalised electron to pass the charge)
Explain why ionic compounds have a giant structure
Ionic compounds have giant structures because the ions keep their charge and attract up to 6 other ions – forming a giant lattice
What does monatomic mean and why are noble gases monatomic?
Monatomic means an atom which only exists on its own (does not react)
Noble gases are monatomic as they have a full shell and are un-reactive
What does diatomic mean and why are elements such as the halogens, hydrogen and oxygen diatomic?
Diatomic – atoms in pairs, e.g. H2 and O2
Halogens will form diatomic molecules because they covalently bond with each other, forming pairs
What is the bonding in metals like?
The bonding in metals creates delocalised electrons (free to move and pass on electrical current)
Why do metals conduct electricity?
The bonding in metals creates delocalised electrons (free to move and pass on electrical current)
Why do ionic compounds conduct electricity when they are dissolved / molten?
Ionic compounds conduct electricity when dissolved or molten because they remain as ions (which will pass a current)
What are the symbols for these compounds?
Sulfuric acid
Sodium hydroxide
Nitric acid
Sulfuric acid = H2SO4
Sodium hydroxide = NaOH
Nitric acid = HNO3
Use diagrams to show how magnesium oxide forms ionic bonds
Use diagrams to show how calcium chloride forms ionic bonds
Use diagrams to show how methane (CH4) is formed
Use diagrams to show how ammonia (NH3) is formed
What are the symbols for these compounds?
Magnesium oxide
Ammonia
Methane
Magnesium oxide = MgO
Ammonia = NH3
Methane = CH4
Which group of the periodic table do not form ions?
Explain why this is
Noble gases do not form ions as they already have a full outer shell
What are the names of the following groups in the periodic table?
Group 1
Group 2
Middle metals
Group 7
Group 0
Group 1 = alkali metals
Group 2 = alkaline Earth metals
Middle metals = transition metals
Group 7 = halogens
Group 0 = Nobel gases
What are nano-materials and what are they used for?
Nano-materials (1-100nm) are very small (one nano-metre = one-thousand-millionth of a metre)
They are used for self-cleaning coats on glass etc…
What are smart materials and what are they used for?
Smart materials return to their original shape, e.g. metals which can be stretched and then return to their original shape (metals used in braces / spectacles)
What is a macromolecule?
Give some examples
Macromolecules – are formed by giant covalent bonds, e.g. diamond, graphite, silicon dioxide etc…
What is the bonding like in diamonds?
Each carbon atom forms 4 covalent carbon-carbon bonds with the carbons around them creating a giant structure and makes them very hard
What is the bonding like in graphite?
Each carbon forms 3 covalent carbon-carbon bonds with the carbons around them creating a sea of delocalised electrons which will pass an electrical current
What is meant by thermosetting plastic?
Thermosetting – sets when heated and will not melt again, e.g. a kettle
What is meant by thermosoftening plastic?
Thermosoftening – will melt when heated, and can be re-shaped
How is LD polythene and HD polythene made?
LD polythene – heating ethene to 200oC under high pressure
HD polythene – heating ethene to a lower temperature and pressure with a catalysts
What is polymerisation
Polymerisation is when small molecules are joined to make longer, more useful molecules (e.g. ethane makes poly(ethane))
Give 6 uses of polymers
New packaging, waterproof coatings, dental-polymers, hydrogels, smart materials (shape memory polymers)
What are the two types of polymer and how does this affect their properties?
Low density (LD) polymers (often flexible)
High density (HD) polymers (often more rigid)
E.g. LD polythene for plastic bags and HD polythene for water tanks
Why are metals easily shaped?
Metals are easily shaped because the atoms are closely arranged and can slide past one another
How can you calculate atomic mass?
Add the relative atomic masses of the elements within the compound
How can you calculate empirical formula?
Empirical formula (the simplest possible compound) – divide each element by its mass
Divide each result by the smallest result
Round the numbers up to find out the number of each element
How can you calculate percentage yield?
Percentage yield – work out the masses for each compound
Divide the mass of one compound by the mass you have been given
Divide the other compounds by this result
What is relative atomic mass based on?
Relative atomic mass used on a comparison of the mass with 12C isotope
What is a mole and how can the mass of a mole of an element be worked out?
The relative formula mass of a substance (grams) is known as one mole of that substance
How can you calculate the percentage of an element in a compound?
(mass of element ¸ mass of compound) x 100
Give 3 reasons why a reaction may not give the theoretical yield
The reaction may not go to completion because it is reversible
Some of the produce may be lost when it is separated from the reaction mixture
Some of the reactants may react in ways different to the expected reaction
What is theoretical yield?
The maximum yield that could be obtained if all atoms reacted
Why are yields always less than 100%?
Some product / reactant always gets lost along the way
What is a reversible reaction?
Give an example
A reversible reaction is not a permanent reaction and will break back down into the reactants (e.g. the Haber process)
What is equilibrium?
Equilibrium is reached when the reactions occur at exactly the same rate in both directions
What is the Haber process used to manufacture and what is the equation?
Ammonia
N2 + 3H2 → 2NH3
What are the raw materials used for in the Haber process, and where can these be obtained?
Nitrogen – from the air
Hydrogen – from natural gas / water
What are the conditions needed for the Haber process?
Temperature
Pressure
Catalyst
Temperature = 450°C
Pressure = 200atm
Catalyst = iron
What happens to the unused nitrogen and hydrogen?
Unused nitrogen and hydrogen are recycled
During the Haber process how is the ammonia removed?
It is liquefied
How can the relative amounts of substances in a reversible reaction be altered?
Changing the temperature / pressure
How does increasing the temperature affect a reversible reaction?
Increasing the temperature increases the amount of the endothermic side of the reaction
How does decreasing the temperature affect a reversible reaction?
Decreasing the temperature increases the amount of the exothermic side of the reaction (however it also slows it down)
How does increasing the pressure affect a reversible reaction?
Increasing the pressure increases the side of the reaction with the lowest volume
How does decreasing the pressure affect a reversible reaction?
Decreasing the pressure increases the side of the reaction with the highest volume
Why may it be important to companies to understand the conditions of a reversible reaction?
Why may it be important to companies to understand the conditions of a reversible reaction?
What type of salts are made from the following?
Hydrochloric acid
Sulfuric acid
Nitric acid
Hydrochloric acid – chlorides
Sulfuric acid – sulfates
Nitric acid – nitrates
What is the equation for working out speed?
Speed (m/s) = distance (m) / time (s)
What is the equation for working out acceleration?
Acceleration (m/s2) = change in velocity (m/s) / time taken (s)
What is the equation for working out weight?
Weight (N) = mass (kg) x gravity (N/kg)
What is the equation for working out force?
Force (N) = mass (kg) x acceleration (m/s2)
What is the equation for working out work done?
Work done (J) = force (N) x distance (m)
What is the equation for working out momentum?
Momentum (kg m/s) = mass (kg) x velocity (m/s)
What do the parts of the distance-time graph tell you about movement?
a-b = moving
b-c = stopped
c-d = moving quicker (than at a-b as line is steeper)
What do the parts of the velocity-time graph tell you about movement?
a-b = accelerating quickly
b-c = steady speed
c-d = decelerating
d-e = stopped (steady speed)
e-f = accelerating quickly
f-g = steady speed
g-h = decelerating
How can you work out the distance traveled from a velocity-time graph?
Work out the area beneath the graph
When are the forces of an object balanced?
When it is still or travelling at a steady speed
What do unbalanced forces do to the movement of an object?
It will cause the object to speed up / slow down
What is the force of gravity on Earth?
10N/kg (9.8N/kg)
What is the equation for working out power?
Power (P) = work done (or energy transferred) (E) / time take (s)
What is the equation for working out gravitational potential energy?
Gravitational potential energy (Ep) = mass (kg) x gravity (N/kg) x height (m)
How is work done to an elastic object stored?
Via elastic potential energy (shape is changed)
What is Hooke’s law?
Extension of an elastic object is directly proportional to force
Force (N) = spring constant (k) x extension (m)
F = k x e
How would you draw out an example of Hooke’s law in practice?
What happens to extension of an object if the force becomes too great?
The directly proportional extension of the object in relation to the force stops…
When stopping a car what can affect the thinking time?
Drugs and alcohol
Distractions
Tiredness
When stopping a car what can affect the breaking distance?
Speed
Mass of vehicle
Tyres
Brakes
Road surface
Weather
Why do falling objects reach terminal velocity?
The weight remains constant with gravity causing the object to accelerate
Air resistance is small to begin with, but as the object speeds up it increases
Eventually the air resistance will equal the weight (as this does not change)
Once the forces are balanced there can be no change in speed – terminal velocity
What is resultant force and when is the resultant force on an object zero?
The overall force in one direction – this is zero when the object is stationary
What can be described as a fluid?
What happens to the frictional forces as an object accelerates through a solid
Gases and liquids
Frictional forces increase as the speed increases, but eventually reach terminal velocity
What is momentum and what affects it?
Momentum is how quickly each kg of the object is moving – objects with great momentum are harder to stop
Momentum is affected by mass and velocity
What is the equation for working out kinetic energy?
Kinetic energy (J) = ½ mass (kg) x speed2 (m/s)
Ek = ½ mv2
All objects with elastic potential energy are all able to do what?
Return to their original shape
During a collision or explosion between objects, what happens to the momentum?
The momentum in a collision or explosion is conserved
What safety features do you find in cars to help reduce the affect of momentum during a crash?
Cars are designed to convert kinetic energy safely in a crash via: -
Seatbelts
Crumple zones
Air bags
Side impact bars
In a car crash safety features are designed to what?
Increase the time taken to slow the passenger(s) down
How are static charges produced?
Rubbing an object to remove electrons (negative charges)
Objects which gain electrons become negatively charged
Objects which lose electrons become positively charged
When objects collect a static charge, which type of charge moves?
Negative charges only (the electrons can be moved, but the protons are held in the nucleus (not moving))
How does a photocopier use static charges?
Drum of the photocopier has positive charge
When light falls onto the drum it loses its charge – light shines through white bits, so only the black bits of the paper to copy remain charged
Ink is negatively charged so it is attracted to the positive parts of the drum
This is transferred to the paper
How does a smoke precipitator use static charges?
Dust and ash pass through a negatively charged grid and pick up a negative charge
Dust is then attracted to positively charged plates which are shaken and removed at intervals
How can spray-painting use static?
Paint is positively charged – these paint particles repel each other to create a fine mist
Objects being sprayed are negatively charged so the paint is attracted to it
When can static electricity be dangerous?
Static can be dangerous when flammable gases / liquids are used which a spark could ignite
E.g. petrol stations or operating theatres
How can the dangers of static electricity be reduced?
The dangers can be reduced by ‘earthing’ objects to prevent sparks from forming
What happens when 2 like charges are put together?
What happens when 2 opposite charges are put together?
Like charges repel
Opposite charges attract
What is an earth cable and what is it used for?
Earth cables must be good conductors (e.g. copper) to provide the electrons with an easy route to the ground
Why can a build-up in static charges cause a spark?
If the charge on an isolated object is great enough there may be a large enough potential difference between the object and the ground to spark (electrons jump the gap)
What are the symbols for the following: -
Switch
Cell
Battery
What are the symbols for the following: -
LDR
Diode
Resistor
What are the symbols for the following: -
Fuse
Lamp
Variable resistor
What are the symbols for the following: -
Voltmeter
Ammeter
Thermistor
What component does this current/voltage graph represent?
A resistor at a constant temperature
What component does this current/voltage graph represent?
A filament lamp
What component does this current/voltage graph represent?
A diode
What is the equation for working out potential difference?
Potential difference (V) = current (A) x resistance (Ω)
What is the equation for working out resistance?
Resistance (Ω) = potential difference (V) ÷ current (A)
Explain the shape of the voltage / current graph for a filament lamp
As the voltage is increased the current increases
As the voltage is increased the filament gets hot, exciting the particles making it harder for the electrons to flow through (therefore reducing the current increase)
Why does an increase in temperature reduce the current?
The heat excites the metal particles vibrating them more – this makes it harder for the electrons to flow through, therefore reducing the current
What is a diode and how does current flow through it?
A diode is a component which only allows energy to flow through in one direction
What is a LDR, how does current flow through it and where may it be used?
LDR (light dependent resistors) are affected by light – the resistance decreases as the light increases
These are useful for streetlights
What is a thermistor, how does current flow through it and where may it be used?
Thermistors are resistors which are affected by temperature – the resistance decreases as the temperature increases (this can be used in fridges)
How does resistance affect the current?
The higher the resistance the lower the current
How can you work out the total resistance in a circuit?
To work out the resistance in a circuit add up the resistance of all the individual components
What are the rules for current in a series circuit?
Series circuit – current is the same
What are the rules for the potential difference in a series circuit?
Series circuit – voltage is shared between components (adds up to the total voltage of the battery)
What are the rules for current in a parallel circuit?
Parallel circuit – current is shared between the different branches
What are the rules for potential difference in a parallel circuit?
Parallel circuit – voltage is the same in each branch (the same as the battery)
