A level Biology Paper 2 Revision, Exams of Biology

Download A level Biology Paper 2 Revision and more Exams Biology in PDF only on Docsity! A level Biology Paper 2 Revision Role of producers in an ecosystem - Perform photosynthesis and produce sugar and oxygen It also regulates carbon Role of consumers in an ecosystem - animals, eat plants or other consumers Role of decomposers/saprobionts - - release enzyme onto dead plants/dead animals/animal waste (organic matter) - breaking them down to obtain biological molecules How do organisms get the energy they need? - by breaking down food molecules gradually and capturing their chemical energy Main Source = Glucose Stored as Starch in plants and Glycogen in animals How does energy move through an ecosystem? - Energy moves through an ecosystem when one organism eats another in the trophic level. EXAM QUESTION: PHOTOSYNTHESIS Heat stress decreases the light-dependent reaction of photosynthesis. Explain why this leads to a decrease in the light-independent reaction. - 1. No ATP; 2. No reduced NADP; A decrease in the activity of the enzyme rubisco would limit the rate of photosynthesis. Explain why. - 1. Less carbon dioxide reacts with RuBP; 2. Less GP; Where precisely is rubisco found in a cell? - Stroma of a cholorplast EXAM QUESTION: PHOTOSYNTHESIS The scientists concluded that heat stress reduces the activity of rubisco in plant leaves by affecting rubisco activase. Use all the information to evaluate their conclusion. - 1. Rubisco activity increases with temperature 2. (Rubisco) activase activity decreases at high temperatures 3. Graphs suggest activase does not affect activity of rubisco There are different types of gene mutation. box Put a X in the box next to the statement which describes incorrectly the effect of the mutation in an exon of a gene. - An inversion will result in a change in the number of DNA bases. X Describe how alterations to tumour suppressor genes can lead to the development of tumours. - 1. Increased methylation of tumour suppressor - Glucose = respiration, store as starch, make cellulose - Amino Acids = make proteins e.g. enzymes Why do consumers (animals) need biological molecules? - - Glucose = respiration, store as glycogen - Amino Acids = make proteins e.g. enzymes - Fatty Acid & Glycerol = make triglyceride as energy store and insulation/protection, make phospholipid for membranes What does a Pyramid of Biomass represent? - The biomass of the organisms at each stage in a food chain. What is biomass? - mass of living tissue (based on dry mass, water excluded) Name 4 components of the structure of a chloroplast? - has a double membrane (outer and inner) contains discs called thylakoids (contain chlorophyll) a stack of thylakoids = granum thylakoids are surrounded by a fluid material called stroma Where does the light dependent reaction take place? - on thylakoids, makes ATP and reduced NADP Where does the light independent reaction take place? - in stroma, uses the ATP and reduced NADP to make glucose What are the limiting factors for photosynthesis? - Light and CO2 and Temperature Effect of limiting Light on the calvin cycle? - RuBP decreases - being converted into GP but not being reformed from TP (no ATP) GP increases - not converted into TP (no ATP/reduced NADP) but is being formed from RuBP