GLOBAL WARMING The sun radiates energy and is absorbed by the earth which re-emits infra-red radiation. Gases that stop infrared radiation escaping from the earth are greenhouse gases. This keeps the earth warm enough for life and is called the greenhouse effect....
CARBON CYCLE The circulation of carbon Carbon dioxide levels have been rising, suggesting the cycle isn’t in balance due to mainly combustion of fossil fuels and deforestation. Coal is a fossil fuel formed from trees fallen into anaerobic conditions millions of years...
MAINTAINING THE BALANCE Biofuels – fuels directly from biomass which are burnt to release energy, producing carbon dioxide. Because the amount of carbon dioxide released when burnt is the same removed by photosynthesis, plants are carbon neutral so have no net...
ENZYME ACTIVITY Temperature has a direct effect on enzyme activity – at low temperatures enzyme activity is low because substrate and enzyme don’t collide often. This increases with temperature until optimum temperature is reached. Any higher than the optimum...
SPECIATION Speciation is the formation of a new species. Species = A group of organisms with similar morphology, physiology and behaviour which can interbreed and are reproductively isolated from other species. For a new species to arise, a group of individuals has to...
EVOLUTION Evolution is a change in allele frequency in a population of organisms over time. Natural selection Many organisms are unable to move to new habitats and will only survive if they can adapt to new conditions – there is a struggle for existence. Organisms...
VALIDATING SCIENCE In order to test theories, data needs to be collected to prove or disprove it. Scientists within the scientific community accept evolution as there is evidence to make it reliable and valid. Scientists validate data in 3 ways: Scientific journals –...
CALCULATIONS Percentage increase = bigger – smaller / original x 100
INVESTIGATING POPULATIONS Looking at the abundance and distribution of a species in an area Abundance = number of individuals of one species in a particular area. Distribution = a particular species within the area being investigated Random sampling: Choose an area to...
ENERGY TRANSFER Energy is transferred in an ecosystem. Autotrophs make their own food, heterotrophs cannot so eat to gain energy. Primary consumers (herbivores) eat plants (autotrophs). Secondary consumers (carnivores) eat secondary consumers and are sometimes the top...
CLIMATE CHANGE Climate change is supported by evidence from temperature records, pollen grains in peat bogs and tree rings. Temperature records Some go back 2 or 3 centuries – long-term data can be recorded with thermometers. Pollen analysis Pollen grains are...
ON THE WILD SIDE PHOTOSYNTHESIS Producers (autotrophs) make their own food by photosynthesis 6CO2 + 6H20 à 602 + CH12O6 (in the presence of light and chlorophyll) Photolysis is used, the process of splitting water using light energy Photosynthesis stores energy as...
CHLOROPLASTS Photosynthesis occurs in the chloroplasts (small, flattened organelles). Thylakoid membranes: A system of interconnected, flattened fluid filled sacs. Proteins including photosynthetic pigments and electron carriers are in the membrane and are involved in...
LIGHT DEPENDENT REACTIONS In the thylakoid membrane ADP + Phosphate à ATP Produce reduced NADP, ATP and waste oxygen Light energy provided by sun Light absorbed by chlorophyll pigment in chloroplasts Light energy excites electrons in the chlorophyll so they get...
LIGHT INDEPENDENT REACTIONS In the stroma Also called the Calvin Cycle ATP à ADP + Phosphate RuBP combines with carbon dioxide from the air to form an unstable 6C compound The enzyme RUBISCO catalyses the break down of the unstable 6C compound into two molecules of a...
PHOTOSYNTHESIS KEY WORDS Phospohorylation: Adding phosphate to a molecule (ADP is phosphorylated into ATP) Photophosphorylation: Adding of a phosphate molecule using light Photolysis: Splitting of a molecule using light Hydrolysis: Splitting of a molecule using water...
ATP (ADENOSINE TRIPOSPHATE) Immediate source of energy in cells Respiration: energy released from glucose is used to make ATP Carries energy around the cell where it is needed ATP is synthesised from ADP and inorganic phosphate using energy ATP diffuses to the part of...
ECOSYSTEMS The biosphere is the part of the earth inhabited by living organisms. Ecosystems exist in the biosphere, and within ecosystems, there can be different habitats, each with its own distinct conditions. A community of organisms live in ecosystems because they...
SUCCESSION = The process by which an ecosystem changes over time – the biotic conditions change as the abiotic conditions change. A pioneer species is the first plant to colonise the bare ground. Only the species that can cope with the extreme conditions will grow and...