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Revision session 3
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Multiple choice 1 What is the major site of aerobic respiration in cells? a)The nucleus. b)The flagellum. c)The mitochondria. d)The Golgi apparatus. Which of the following statements about aerobic and anaerobic respiration is correct? a) During anaerobic respiration more energy is extracted from fuel molecules than during aerobic metabolism. b) Both processes occur in the cytoplasm and compete for fuel substances with each other. c) Only cells living in oxygen-free environments use anaerobic respiration, all other organisms rely on aerobic respiration alone. d) The end products from anaerobic respiration are more toxic to cells than the end products of aerobic respiration.
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Multiple choice 1 What is the major site of aerobic respiration in cells? a)The nucleus. b)The flagellum. c)The mitochondria. d)The Golgi apparatus. Which of the following statements about aerobic and anaerobic respiration is correct? a) During anaerobic respiration more energy is extracted from fuel molecules than during aerobic metabolism. b) Both processes occur in the cytoplasm and compete for fuel substances with each other. c) Only cells living in oxygen-free environments use anaerobic respiration, all other organisms rely on aerobic respiration alone. d) The end products from anaerobic respiration are more toxic to cells than the end products of aerobic respiration.
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Short answer 2004 35a & b Cells use a range of structures and processes to regulate their metabolism and interact with their environment. (a) Give two reasons why all organisms need each of the following (i) DNA (ii) enzymes (b)ATP is an important molecule for energy flow in living organisms. List four functions that ATP performs in cells.
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Short answer 2004 35a & b Cells use a range of structures and processes to regulate their metabolism and interact with their environment. (a) Give two reasons why all organisms need each of the following (i) DNA Blueprint for cellular control/structure/ Pass heredity material to the next generation (just heredity OK)/store genetic material/ Protein synthesis 1 mark each to maximum of 2 (ii) enzymes Regulate cellular reactions/ Accelerate/catalyse cellular reactions/lower activation energy/ Produce energy from organic compounds/ Synthesize new compounds 1 mark each to maximum of 2 (b)ATP is an important molecule for energy flow in living organisms. List four functions that ATP performs in cells. Movement of organelles/exocytosis/endocytosis/pinocytosis Maintenance of the cellCell divisionActive transport Storage of energyTransportable form of energy Rechargeable Packaging energy convenientlyTransmitting messages (nerve cells) Building complex molecules/photosynthesis/protein synthesis/lipid synthesis 1 mark/line, maximum 4
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Short answer 2004 35c c) Although all animals need oxygen to survive, some can withstand a lack of oxygen for long periods (i)Name the metabolic process for obtaining energy from the breakdown of organic compounds in the absence of oxygen. (ii)Compare the amount of ATP produced from glucose in the presence and absence of oxygen. (iii)Name the end products from the breakdown of glucose in the presence of oxygen in a mammal. (iv) Name the end products from the breakdown of glucose in the absence of oxygen in a mammal
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Short answer 2004 35c c) Although all animals need oxygen to survive, some can withstand a lack of oxygen for long periods i) Name the metabolic process for obtaining energy from the breakdown of organic compounds in the absence of oxygen. Anaerobic respiration ii) Compare the amount of A TP produced from glucose in the presence and absence of oxygen. 36 or 38 ATP with oxygen, 2 ATP without (or more ATP with oxygen) iii) Name the end products from the breakdown of glucose in the presence of oxygen in a mammal. Carbon dioxide and water (must be both for mark) iv) Name the end products from the breakdown of glucose in the absence of oxygen in a mammal Lactate or lactic acid (if carbon dioxide mentioned, no mark. If energy mentioned, OK
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Short answer 2004 35d Photosynthesis is the basis of almost every ecosystem on earth. (i)Define photosynthesis. (ii)List the raw materials of photosynthesis (iii)What is the function of chloroplasts? (iv)What are the products of photosynthesis?
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Short answer 2004 35d Photosynthesis is the basis of almost every ecosystem on earth. (i)Define photosynthesis. The process by which organic compounds/sugars/carbohydrates (food NOT acceptable) are synthesized from inorganic compounds using solar energy/Light (solar) energy converted to chemical energy OR Word equation OR Formula equation (doesn’t need to be balanced) (ii)List the raw materials of photosynthesis Carbon dioxide and water (chlorophyll and light NOT accepted) (iii)What is the function of chloroplasts? Chloroplasts are the site of photosynthesis OR organelle converting carbon dioxide and water to organic compounds using solar energy OR contains chlorophyll and absorbs light or solar energy (iv)What are the products of photosynthesis? Oxygen, and organic compounds/sugars/carbohydrates/glucose/starch
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Short answer 2004 35e Some photosynthetic and heterotrophic organisms live in a mutualistic relationship. This is a type of relationship from which both organisms benefit. An example of this is found in many hard corals. The coral animals harbour small, single-celled photosynthetic algae within their cells. (i)Suggest two processes of the coral animal that are assisted by materials obtained from the photosynthetic algae. (ii) Suggest two benefits that the photosynthetic algae obtain from living inside the cells of the coral animal.
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Short answer 2004 35e Some photosynthetic and heterotrophic organisms live in a mutualistic relationship. This is a type of relationship from which both organisms benefit. An example of this is found in many hard corals. The coral animals harbour small, single-celled photosynthetic algae within their cells. i) Suggest two processes of the coral animal that are assisted by materials obtained from the photosynthetic algae. Respiration/Oxygen assists respiration Feeding/nutrition/Organic compounds food)/Growth/Consumption (ii) Suggest two benefits that the photosynthetic algae obtain from living inside the cells of the coral animal. Shelter/Protection/Stable environment Carbon dioxide Nitrogen compounds (cellular wastes)
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Extended answer 2000 36d Compare the processes of anaerobic respiration and aerobic respiration in terms of sites where they occur in the cell, requirements, products (including wastes) and the circumstances under which they occur.
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Extended answer 2000 36d Compare the processes of anaerobic respiration and aerobic respiration in terms of sites where they occur in the cell, requirements, products (including wastes) and the circumstances under which they occur. anaerobicaerobic SiteCytoplasmCytoplasm and mitochondria RequirementsGlucose, ADPGlucose + oxygen, ADP ProductsLactic acid (animals) CO 2 and alcohol (plants) 2 ATP CO 2, water, 36 – 38 ATP heat CircumstancesAnaerobic conditions – low oxygen Many microbes Aerobic conditions – high oxygen Most multicellular organisms
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Extended answers 2006 37(a) Photosynthesis is not the only form of primary production. Some single- celled organisms produce organic molecules from carbon dioxide using energy stored in molecules such as hydrogen sulphide (H 2 S). This is called chemosynthesis. A word equation for chemosynthesis is: Carbon dioxide + water + oxygen + hydrogen sulphide 4 organic compounds + sulphuric acid Compare and contrast chemosynthesis and photosynthesis, focusing on (i) the raw materials, (ii) the source of energy transferred to carbon products, and (iii) the ecological implications of the two forms of production of organic molecules from carbon dioxide.
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Extended answers 2006 37(a) Photosynthesis is not the only form of primary production. Some single-celled organisms produce organic molecules from carbon dioxide using energy stored in molecules such as hydrogen sulphide (H 2 S). This is called chemosynthesis. A word equation for chemosynthesis is: Carbon dioxide + water + oxygen + hydrogen sulphide 4 organic compounds + sulphuric acid Compare and contrast chemosynthesis and photosynthesis, focusing on (i) the raw materials, (ii) the source of energy transferred to carbon products, and (iii) the ecological implications of the two forms of production of organic molecules from carbon dioxide. Raw materials for photosynthesis are CO 2 and water* Raw materials for chemosynthesis are CO 2, water, O 2 and H 2 S Energy for photosynthesis comes from sunlight* Energy for chemosynthesis comes from chemical bonds in H 2 S Products from photosynthesis are organic compounds and O 2 * Photosynthesis releases O 2 into the atmosphere and makes respiration possible Chemosynthesis uses O 2 and does not release it Chemosynthesis cannot exist without some photosynthetic organisms elsewhere Chemosynthesis produces sulphuric acid, therefore, chemosynthetic organisms must be acid tolerant or possibly in water so the acid is diluted and removed Photosynthesis requires sunlight and is restricted to sunlit habitats Chemosynthesis can occur in dark habitats providing other inputs are available OR chemosynthesis can sustain communities in habitats without light Both processes convert inorganic materials to organic compounds and are primary producers Chemosynthesis only occurs in special environments, as they need H 2 S Both processes remove CO 2 which is important in the carbon cycle/decrease global warming * If word equation for photosynthesis given, allocate marks according to points above.
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Energy transfers Energy transfer occurs in all cellular activities. For each of the following processes involving energy transfer, explain how each functions in the cell and give an example. Explain how ATP is involved in each example you choose. Aerobic RespirationAnaerobic respiration Photosynthesis
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Anaerobic respiration Occurs in the cytoplasm Does not need oxygen Involves 2 processes – glycolysis and fermentation Glycolysis Glucose is broken down into 2 pyruvate (pyruvic acid) molecules Reactions use 2 ATP Reactions make 4 ATP Net ATP = 2/glucose molecule In animals Pyruvate is converted to lactic acid In plants and fungi Pyruvate is converted to ethanol and carbon dioxide ATP is the end product – used to capture energy of reactions
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Aerobic respiration Occurs in the mitochondrion Needs oxygen Involves Transition reaction, Krebs cycle and Electron transport chain Involves many reactions and enzymes Produces 36 ATP Waste products are carbon dioxide and water ATP is the end product – used to capture energy of reactions
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Photosynthesis Uses light energy to convert inorganic molecules to organic molecules Occurs in the chloroplasts of plant cells and some protists and the cytoplasm of cyanobacteria Occurs as a series of reactions, involving many different enzymes Involves light dependent and light independent reactions (the Light and Dark reactions) ATP is used to transfer energy from the light reactions to the dark reactions Net equation: carbon dioxide + water + solar energy glucose + oxygen + water
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Photosynthesis Discuss the effect of each of the following factors on the rate of photosynthesis in a living plant: carbon dioxide light intensity temperaturewater conservation
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Photosynthesis Discuss the effect of each of the following factors on the rate of photosynthesis in a living plant: carbon dioxide light intensity temperaturewater conservation As stoma close to reduce water loss, carbon dioxide levels fall and photosynthesis decreases
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DNA Deoxyribonucleic acid or DNA has been described as the chemical basis of heredity. Discuss present-day concepts regarding its: chemical nature and physical structuremode of duplication relationship to protein synthesis
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Why is DNA important It can be inherited (passed on in cell divisions) It can easily be copied with a high degree of accuracy It controls which proteins are made
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Structure of DNA DNA is a coiled double helix made up of nucleotides on a sugar phosphate backbone
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DNA is made of nucleotides
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DNA replication Occurs in interphase – before mitosis starts One set of enzymes split the strands Another set of enzymes join new nucleotides to each strand Nucleotides match up by the base pairing rule (C – G, A – T) The end result is two identical strands, joined at a point called the centromere
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DNA controls protein synthesis
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