AQA A LEVEL BIOLOGY

• LDR is the distance between two points
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• AQA A Level Biology::AQA Biology AS-Level::3.1 - Biological Molecules::3.1 - Exam Questions Why is (control) used? - as a control - to show effect of x - to show that x does not affect results - to show that only y causes the change - may be used as baseline value to investigate effect of treatments
• AQA A Level Biology::AQA Biology AS-Level::3.1 - Biological Molecules::3.1 - Exam Questions Why is a representative sample important? - more reliable mean
• AQA A Level Biology::AQA Biology AS-Level::3.2 - Cells::3.2 - Exam Questions Mitosis is important in the life of an organism. State reasons why. [4] MS 1. Growth / increase in cell number; 2. Replace cells / repair tissue / organs / body; 3. Genetically identical cells; 4. Asexual reproduction / cloning;
• AQA A Level Biology::AQA Biology AS-Level::3.1 - Biological Molecules::3.1 - Exam Questions A decrease in temperature decreases the kinetic energy of molecules in a solution. Explain how a decrease in temperature decreases the rate of an enzyme-controlled reaction. MS [2] molecules moving less/slower;reduces chance of collision (between enzyme and substrate)/of enzyme-substrate complexes being formed;
• AQA A Level Biology::AQA Biology AS-Level::3.2 - Cells::3.2.1 - Cell Structure Explain why an electron microscope shows more detail of cell structure than a light microscope [2] electron microscope has a greater resolving power / objects closer together can be distinguishedelectron (beams) have a shorter wavelength;
• AQA A Level Biology::AQA Biology AS-Level::3.3 Organisms exchange substances with their environment::3.3 - Exam Questions Abdominal pumping increases the efficiency of gas exchange between the tracheoles and muscle tissue of the insect. Explain why. ( 2 marks) More air / oxygen enters / air / oxygen enters quickly / quicker; (So) maintains / greater diffusion or concentration gradient;
• AQA A Level Biology::AQA Biology AS-Level::3.1 - Biological Molecules::3.1.6 - ATP Recall the uses of ATP. [6] provides energy for - synthesis of macromolecules - muscle contraction - active transport - secretion Phosphate Released: - phosphorylation of molecules - can active other key bio molecules
• AQA A Level Biology::AQA Biology AS-Level::3.1 - Biological Molecules::3.1 - Exam Questions What are the 3 aspects to consider when choosing a temperature for an experiment? - sufficient kinetic energy - does not denature proteins - optimum
• AQA A Level Biology::AQA Biology AS-Level::3.2 - Cells::3.2.1 - Cell Structure Explain the function of the golgi apparatus + vesicles Packages and mods proteins (e.g adding a carbohydrate to it)Vesicles transport proteins + lipids out of the cell to the CS membrane (using exocytosis)
• AQA A Level Biology::AQA Biology AS-Level::3.2 - Cells::3.2.1 - Cell Structure How are photomicrographs formed using a TEM? e- gun produces a beam of e- -> focused on specimen by electromagnet.beam passes through specimen, denser areas are absorbed causing dark spots.
• AQA A Level Biology::AQA Biology AS-Level::3.2 - Cells::3.2.1 - Cell Structure How are SEM images created? e- beam is directed from abovee- beams are scattered which are analysed by a computer to build a 3-D image.
• AQA A Level Biology::AQA Biology AS-Level::3.2 - Cells::3.2.1 - Cell Structure what are the functions of glycoproteins? [2] - act as recognition sites - help cells attach to one another + form tissues (e.g lymphocytes can recognise an organism's own cells)
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Cryospheric water is the water locked up on the Earth's surface as ice.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Briefly explain what the hydrosphere is The layer of water at or near the Earth's surface. It includes all liquid and frozen surface waters, groundwater held in soil & rock and atmospheric water vapour.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle What is terrestrial water? The water in groundwater, soil moisture, lakes, wetland and rivers
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Complete the following: All water - Oceans: 97% - Fresh water 3% Fresh water - Ice caps and glaciers 79% - Groundwater 20% - Easily accessible surface freshwater 1% Easily accessible surface freshwater - Lakes 52% - Soil moisture 38% - Atmospheric water vapour 1% - Water within living organisms 1% - Rivers 1%
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle The lithosphere consists of water stored in the crust and upper mantle
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Sea ice forms when...? Why does it not raise sea level? Water in the oceans is cooled to temperatures below freezing. It does not raise sea level because it is formed from ocean water.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Where do ice sheets form? In area where snow that falls in winter does not melt entirely over the summer.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle How do ice sheets form? Over thousands of years, layers of snow pile up into thick masses of ice. This grows thicker and denser over time, causing the snow to become compressed.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Ice caps are thick layers of ice that are smaller than 50,0002.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Ice caps are usually found in mountainous areas.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Alpine glaciers are thick masses of ice found in deep valleys or upland hollows. They are important in the Himalays specifically in that they form a unique reservoir which supports perennial rivers. This leads to an important source of water for millions of people in South Asian countries such as India
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle State the four classes that terrestrial water falls under: Surface water Groundwater Soil water Biological water
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Surface water is the free-flowing water of rivers as the well as water of ponds and lakes
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Rivers make up how much of all water in terms of surface area? 1,000,000 kms or 0.0002 %
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle True or false: the majority of lakes in the world are salt water False: They are mostly freshwater
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle In which Hemisphere are there more lakes? Northern, particularly in Canada
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle What is a wetland? An area of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing where there is a dominance by vegetation.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Explain a wetland in simple terms Area where water covers the soil and present or near the surface at all times during the year
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Why are wetlands so biodiverse? They can support aquatic and terrestrial species. Prolonged presence of water creates conditions that favour the growth of specially adapted plants and promotes wetland-specific soils.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Groundwater is... water that collects underground in the pore spaces of rock.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle What is the water table? The depth at which soil pore spaces or fractures and voids in r ock become completely saturated with water.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Why is the amount of groundwater decreasing? Extensive extraction for use of irrigating agricultural land.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle What is 'soil water'? Water held together with air in the unsaturated upper weathered layers of the Earth.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Finish this sentence Soil moisture is a key variable in controlling the exchange of water and heat energy between the land surface and the atmospher through evaporation and transpiration
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle What is biological water? Water stored in all biomass.
• AQA A Level Biology::AQA Biology A2 Level::AA - Essays::ALEVEL GEO::1.2 The water cycle Suggest why the atmosphere is very dry in the poles but very humid in the tropics. Cold air struggles to hold much water vapour. Comparatively, hot air carries a lot of water vapour.