Y9 Biology Revision Booklet PDF

Y9 assessment revision booklet  Biology Classification Species: a group of organisms that can reproduce to produce fertile offspring Living things are classified depending on their structure...

Y9 assessment revision booklet  Biology Classification Species: a group of organisms that can reproduce to produce fertile offspring Living things are classified depending on their structure and characteristics (features they share) by Carl Linnaeus, who developed the binomial system. This classification system: Helps us understand how living things are related Helps us recognise biodiversity (variety of different species) Used universally, so scientists can communicate without confusion The binomial system- names of organisms with Latin words. 1st word is the genus, 2nd word is the species. Ex. humans are homo sapiens. We belong to the homo genus and the sapiens species. (Note: Pupils do not need to know the binomial names of organisms- apart from homo sapiens) Taxonomy- Organisms are classified according to this hierarchy. Funny mnemonic to help with memorising the order- Development of Classification Organisms share features because descend from a common ancestor. Improvements in microscopes allow evidence of internal structures to be more developed, which increases our understanding of internal processes. DNA sequencing allowed us to classify organisms using a more scientific approach. The more similar the sequence, the more closely related 2 species are. Three Domain System Carl Woese developed the three-domain system to classify organisms as: Archaea (primitive bacteria) Bacteria (true bacteria) Eukaryota (protists, fungi, plants and animals) Evolutionary trees Represent relationships between a set of organisms. The tips represent different species and where branches join represents a common ancestor. Another example of evolutionary trees. The lemur is the first primate to evolve. The chimpanzee is most closely related to the human.  Food Chains and Food Webs Keyword Definition A community of organisms & non-living components of an area and their Ecosystem interactions. Community All of the populations (of different species) in a habitat. Habitat Where an organism lives. Interdependence One species depends on others (ex. for food). Stable A community where all the species and environmental factors are in balance, so community population sizes remain fairly constant. Organisms (in an ecosystem) are organised into levels. Producer: Plants and algae, which photosynthesise. Primary consumer: Herbivores, which eat producers. Secondary consumer: Carnivores, which eat primary consumers. Tertiary consumer: Carnivores. They eat secondary consumers. Within a community energy is transferred as one organism consumes (eats) another. Feeding relationships within a community can be represented by food chains. The arrows in a food chain (what is eaten by what) show the direction of energy flow when one organism consumes another. The trophic level describes which role they play within the food chain  Biotic and abiotic factors Biotic factors: Living factors that can affect a community. availability of food (organisms will die if they have no prey, thus, population would decrease) new predators arriving (new predators will kill more prey, thus, population would decrease) new pathogens (disease can kill large numbers of a population, this will also negatively affect any predators of that organism) one species out-competing another (Animals compete for- food, territory, mates and shelter. Plants compete for- water, sunlight, space and minerals) Abiotic factors: Non-living factors which can affect a community. light intensity (less photosynthesis for green plants, thus, producers and primary consumers would decrease) temperature (limits photosynthesis) moisture levels (limits photosynthesis) soil pH and mineral content (limits plant growth- producers could decrease in numbers) wind intensity and direction (affects seed dispersion, with little or no wind, seeds can’t be dispersed from parent plant, leading to more competition for space) carbon dioxide levels for plants (limits photosynthesis) oxygen levels for aquatic animals (limits respiration in aquatic animals) Sampling Quantitative data on the distribution and abundance of organisms can be obtained by: random sampling with quadrats sampling along a transect Quadrat: Square frame of known area. Used to determine the distribution or abundance of plants / slow moving animals in a given area. Abundance: How many living organisms there are. Distribution: How they are spread out. Random sampling 1. Divide the area into a grid using tape measures. Generate random numbers (using random number generator): avoids bias. 2. Use pairs of the random numbers as co-ordinates to place the quadrats in the field. 3. Use a large number of quadrats to be representative of the area and to improve reliability of the results. 4. Count the numbers of samples in each quadrat. 5. Find the mean number of samples in each quadrat. 6. Multiply the mean number of samples in 1 quadrat by the total number of quadrats that would fit into the field. Transects A transect is a line across a habitat or part of a habitat. It can be as simple as a string or rope placed in a line on the ground. The number of organisms of each species can be observed and recorded at regular intervals along the transect. Transects are used to investigate how distribution changes across an environment. Steps place a tape measure across field place quadrats next to the tape count the number of plants in the quadrat repeat every 2 metres/ regular intervals  Chemistry Law of conservation of mass The law of conservation of mass states: No atoms are lost or made during chemical reaction Mass of the products equals the mass of reactants This means that chemical reactions can be represented by symbol equations which are balanced in terms of the numbers of atoms of each element involved on both sides of the equation. Balancing equations A(s) + B(aq) → C(aq) + D(g) + E(l) Balanced symbol equations include state symbols. State symbols Solid (s) Liquid (l) Aqueous solution (aq) Gas (g) Aqueous is not a state of matter Counting atoms Chemical formula can give you information about a substance: Total number of atoms in a molecule. The total number of each atom in a molecule. The rules for balancing equations: 1) Determine number of atoms for each element. 2) Pick an element that is not equal on both sides of the equation. 3) Add a coefficient in front of the formula with that element and adjust your counts. 4) Continue adding coefficients to get the same number of atoms of each element on each side.  Development of atom The model of the atom changed as new evidence was discovered. John Dalton Atoms were thought to be tiny spheres that could not be divided. First subatomic particle to be discovered was the electron which is negatively charged. Led to the plum pudding model of the atom. J.J Thompson- Plum pudding model It is a ball of positive charge with electrons embedded in the ball of positive charge. No empty space in the atom Mass spread throughout Rutherford (with assistants: Geiger and Marsden) Alpha particles scattering experiment - firing alpha particles at very thin sheets of gold foil. Following their work, a new model of the atom, called the ‘nuclear’ model was suggested. Results and conclusion of the alpha particle scattering experiment Result 1: Most alpha particles passed straight through the gold foil Conclusion: The mass of the atom is concentrated in the nucleus Conclusion: Most of the atom is empty space Result 2: Some alpha particles were deflected Conclusion: The atom has a small positively charged nucleus The plum pudding model does not explain the results of the alpha particle scattering experiment as it shows the whole atom as a ball of positive charge with no empty space. Therefore, the experiment led to the plum pudding model of the atom being replaced with the nuclear model of the atom. Nuclear model (Rutherford) Positive charge concentrated at the centre Electrons outside the nucleus Most of the atom is empty space Mass is concentrated at the centre Niels Bohr suggested: Electrons orbit the nucleus Electrons are at specific distances from the nucleus Later experiments Positive charge of any nucleus could be subdivided into a whole number of smaller particles, each particles having the same amount of positive charge (protons) The second particle to be discovered is proton. James Chadwick Provided the evidence to show the existence of neutrons within the nucleus. Discovery of subatomic particles: Date of discovery Subatomic particle 1897 Electron 1920 Proton 1932 Neutron Development of the periodic table The modern periodic table: The periodic table is arranged in order of atomic number (proton number). Elements are arranged in groups and periods. Groups are vertical columns. Periods are horizontal rows. Transition metals are located between group 2 and 3. The group number indicates the number of electrons atoms have in their outer shell. The period number indicates the number of electron shells an atom has. Elements in a group have similar properties because they all contain the same number of electrons in the outer shell. Electrons are responsible for chemical reactions. The table is called a periodic table because similar properties occur at regular intervals. The early periodic table John Newlands and his periodic table Ordered his table in order of atomic weights Realised similar properties occurred every eighth element – law of octaves Had more than one element in a box Noble gases are missing as they were not discovered Disadvantages Did not leave gaps Had many dissimilar elements in a column. E.g. Iron and oxygen are in the same column. Dmitri Mendeleev and his periodic table Ordered his table in order of atomic weights, but not always strictly – i.e. in some places he changed the order based on atomic weights. E.g. He changed Te and I around. Left gaps for elements that he thought had not been discovered yet. Noble gases are missing as they were not discovered Reasons why Mendeleev’s periodic table was accepted Predicted properties of undiscovered elements Elements with properties predicted by Mendeleev were discovered Elements were discovered which fitted into the gaps so elements with similar properties could be placed together. Atoms into ions Atoms into ions When atoms react, they take part in bonding which gives them a stable arrangement of electrons (full outer shell) like the noble gases in group 0. Ions are charged particles. They are made when electrons are lost or gained from an atom. Atoms lose or gain electrons to form a stable electronic structure. Metals: Metals lose electrons from their outer shell forming positive ions. The number of electrons lost depends on the group they are in: Group 1 metals loses 1 electron forming +1 ion Group 2 metals loses 2 electrons forming +2 ion Group 3 metals loses 3 electrons forming +3 ion Non - metals: Non-metals gain electrons in their outer shell forming negative ions. The number of electrons gained depends on the group they are in: Group 6 metals gain 2 electrons forming -2 ion Group 7 metals gain 1 electron forming -1 ion Negatively charged ions have the end of the element name replaced with –ide.  Physics Energy transfer Forms of energy Type of energy Description Examples Kinetic energy Energy of a moving object. An athlete sprinting on a track Thermal/heat energy Energy associated with heat. Hot cup of tea Light Energy Also called radiant energy. Light bulbs, Bunsen flame Gravitational Energy stored in objects which are above the Bungee jumper, a book potential energy ground and can fall. falling Chemical energy Energy stored in chemicals, food and fuel. Food, batteries, burning things Sound energy Energy released by vibrating objects that Talking, tv, radio cause sound to be produced. Elastic Potential energy Energy stored in objects which are stretched or Rubber band, wind-up toy compressed. Electrical energy Any object which involves the use or lightning production of electricity. Nuclear potential Energy stored inside the nucleus of atoms. Nuclear bombs, power Energy stations Magnetic potential Energy stored in a magnetic field. Fridge magnets, compasses, Energy maglev trains Law of conservation of energy: Energy cannot be created or destroyed. Energy can only be transferred from one form to another. Examples of Energy Changes- 1. An object projecting upwards: Kinetic energy (KE) is transferred into gravitational potential energy (GPE) at the highest point, then transferred back to KE as it falls to the ground. 2. A moving object hitting an obstacle: KE is transferred to heat and sound energy when it hits the obstacle. (Sometimes, some of the KE is transferred to the obstacle, causing it to move away.) 3. An object accelerated by a constant force: Chemical / thermal / electrical energy can be used to accelerate the object. It is then converted into KE. 4. A vehicle slowing down: KE of the movement is transferred to sound / thermal energy. 5. An electric kettle bringing water to a boil: Electrical energy into thermal energy (heats the water). A ‘system’ is an object / group of objects. Energy transfers in systems can happen if there’s a change in the way the energy is stored. Example: Energy is transferred by the following ways Mechanical work Electrical work Heating Radiation (Energy transferred as a wave ex. infrared radiation) Energy Dissipation: When there is a change in a system, energy is transferred and some of that is dissipated (wasted / lost to surroundings) Energy resources Non-renewable resource is a source of energy that cannot be replenished as it is used. Fossil Fuels (Coal, Oil & Natural Gas): Chemical store of energy. Nuclear Power: Energy from the structure of the atoms. Using fossil fuels a. Fossil fuel is burnt, turning water into steam. b. Steam rises past turbines and causes them to spin. c. The turbines spin generators to generate electricity. d. Transformers increase the voltage of electricity as it enters the National Grid. e. Transformers decrease the voltage of electricity as it enters homes. Advantages and disadvantages of fossil fuels: Advantages Disadvantages Readily available Will eventually run out Relatively easy to produce energy from them Increasing fuel costs Release CO (greenhouse gas) when burnt 2 Using nuclear power: The process of a nuclear fission power reactor (they do not need to know this but can briefly go over how this process works) Advantages and disadvantages of nuclear power Advantages Disadvantages No release of carbon dioxide (CO ) – greenhouse Non-renewable source – will eventually run out 2 gas Expensive to commission and decommission No release of sulphur dioxide (SO ) – acid rain 2 power stations 1 kg of uranium produces millions times more energy Hazardous radioactive waste produced than 1 kg of coal Danger of release of radioactive materials into the environment Renewable resource is a source of energy that can be replenished as it is used. Biomass: Living / dead material that can be burned as fuel. Energy from the Sun is converted to plant matter (photosynthesis) and that converted to animal matter (eating). Geothermal: Energy from the radioactivity of rocks. Hydro Electric Power: Water is carried to high places, through the water cycle, which occurs due to the Sun’s energy. Solar: Sun’s heat (infra-red) is used to heat water. Or, solar cells convert sunlight to electricity. Tidal: Energy from the gravitational pull of the moon. Wind: Movement of air, air moves from a higher to lower pressure. Caused by air being unevenly heated by the Sun. Waves: Wind blowing on sea, wind’s energy comes from the Sun. Energy from plants Biofuels are fuels made from plant materials. These include biodiesel, made from plant oils, and bioethanol, made by fermenting sugar and wheat. Advantages and disadvantages of biofuel Advantages Disadvantages Uses land that could be used to Renewable source. grow food. Less carbon emissions. When burned, they release as much carbon as they absorb during growth, although some carbon dioxide will be Needs a lot of labour. released during production, eg by the tractor. Bioethanol cannot be used in Reduce our reliance on fossil fuels. cars without modifying the engine. Energy from the wind Advantages and disadvantages of wind power Advantages Disadvantages Renewable source Expensive to build Cheap to run (no fuel costs) Visual pollution (spoils the view) No polluting gases produced Noise pollution (very noisy) Unreliable (depends on the strength of the wind) Energy from falling water Energy in the gravitational store of a body of water held above sea level can be used as the water is allowed to run down pipes containing turbines. There are two ways of doing this: Tidal The Moon's gravitational pull lifts the level of the seas twice a day and this is the force that gives us tidal power. At high tide, the sea is trapped behind a barrage/dam. The water is allowed to run out through pipes that lead back to the sea. As the water runs through the pipes it spins turbines that are linked to generators. Hydroelectric 1. Water is held behind a dam in a lake or reservoir high up a mountain. 2. Rivers or rainfall fills the reservoir. 3. When energy is needed, the water is allowed to run down through pipes to another lake lower down the mountain. 4. As the water runs through the pipes it spins turbines that are linked to generators. 5. The water can be pumped back up during the night when electricity is cheaper. Advantages and disadvantages of water power Advantages Disadvantages Renewable source Visual pollution (spoils the view) Cheap to run (no fuel costs) Damage to the estuary habitats No polluting gases produced Damage to valley habitats by flooding Very reliable Can block access to ports for shipping Can be switched on when Trapped and rotting vegetation can produce greenhouse gases such as needed methane Energy from the sun All our energy comes from the Sun. Advantages and disadvantages of solar power Advantages Disadvantages Renewable source Solar cells are not very efficient It costs a lot of money to make Cheap to run (no fuel costs) them more efficient No polluting gases produced Unreliable as it is not always sunny Solar cells can generate electricity at the top of mountains when there is no connection to the National Grid  Density Density is the amount of mass in a given volume: Mass is the amount of matter in a substance Volume is how much space an object occupies o Solids have the greatest density as there are more particles in the same volume o Gases have the least density as there a fewer particles in the same volume The equation for density is: Where: ρ – density m – mass V – volume Density may have the units kg/m or g/cm 3 3 Mass can be given in g or kg Volume can be given in cm or m 3 3 REGULAR SOLID: Objects that have definite shape Method: 1. Measure the mass by putting it on a balance 2. Determine the volume of the object by measuring the sides with a ruler and multiplying them together. V=lxwxh 3. Calculate density using the formula: Density = mass÷volume Irregular shapes have sides and angles of any length and size. Method: 1. Measure the mass of the irregular object by using a balance. 2. Fill a displacement can/Eureka can with water 3. Water level with spout 4. Place object in water 5. Collect displaced water 6. Use a measuring cylinder to determine the volume of displaced water. Volume of water displaced = volume of irregular object 7. Calculate density using the formula: density = mass ÷ volume