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06/05/2017 B4 The Processes of Life OCR Additional Science M Barker Shirebrook Academy 06/05/2017 B4.1 How do Chemical Reactions take place in living things? Photosynthesis Introduction 06/05/2017 Basically, photosynthesis is the process through which a plant makes large food molecules using carbon dioxide and water and it happens in plants as well as some micro organisms: That’s a nice plant. I’m going to put it in the sun and give it lots of water and air… CO2 H2O Respiration Introduction I enjoy taking samples using quadrats. In order to do this, I need energy. Where does this energy come from? All living things, including plants, get their energy from respiration. Respiration is basically the process of breaking down the large food molecules that were probably originally made in plants. 06/05/2017 Enzyme use in nature 06/05/2017 Enzymes are proteins that speed up chemical uses. Here are two important natural uses for them: Cells use glucose to generate energy – this process is called “respiration”. Respiration happens in mitochodria and is catalysed by enzymes. Photosynthesis is catalysed by enzymes in the cells. Enzymes 06/05/2017 Enzymes are biological catalysts. They help the reactions that occur in our bodies by controlling the rate of reaction. An enzyme is basically a protein molecule made up of long chains of amino acids. Cells make enzymes according to the instructions carried in their genes. The enzyme’s shape helps another molecule “fit” into it: Enzyme This shape can be destroyed by high temperatures or the wrong pH: Substrate The “Active Site” Active site Enzyme Substrate 06/05/2017 Enzymes 06/05/2017 Enzymes work best in certain conditions: Enzymes are denatured beyond 40OC Enzyme activity 400C Temp Could be protease (found in the stomach) Could be amylase (found in the intestine) pH Enzymes are used in industry to bring about reactions at normal temperatures and pressures that would otherwise be expensive. However, most enzymes are denatured at high temperatures and can be costly to produce. pH B4.2 How do Plants make food? 06/05/2017 06/05/2017 Photosynthesis – the 4 things you need SUNLIGHT Gives the plant energy CHLOROPHYLL WATER Travels up from the roots CARBON DIOXIDE Enters the leaf through small holes on the underneath The green stuff where the chemical reactions happen Photosynthesis equations Carbon dioxide + _____ Sunlight Chlorophyll 06/05/2017 glucose + _____ Sunlight 6CO2 + 6H20 Chlorophyll C6H12O6 + 6O2 The GLUCOSE produced by photosynthesis is used by the plant for _______ (through ____________). It is stored in the plant as ___________. Words – respiration, starch, water, oxygen, energy What is the glucose used for? 06/05/2017 1) Glucose (sugar) can be used to make long chains of insoluble starch… Glucose molecules Starch molecule 2) Glucose can be used to make cellulose for cell walls… Glucose molecules Cellulose 3) Glucose can be combined with nitrates to make proteins (for growth)… Glucose molecules Proteins Glucose can also be used for respiration, either by the plant or by what eats it! A Typical Plant Cell: 06/05/2017 Cell wall – made of cellulose which strengthens the cell Cell membrane – controls what comes in and out Large vacuole – contains sap and helps support the cell Chloroplasts – contains chlorophyll and enzymes for photosynthesis reactions Nucleus – controls what the cell does and stores genetic info for making proteins Cytoplasm – Chemical reactions happen here 2 common nutrients… Nitrates: Used to make proteins Lack of it leads to stunted growth Magnesium: Used to make chlorophyll Lack of it leads to yellow leaves 06/05/2017 Diffusion 06/05/2017 Diffusion is when something travels from an area of high concentration to an area of low concentration. For example, consider the scent from a hamburger… The “scent particles” from this hamburger are in high concentration here: Eventually they will “diffuse” out into this area of low concentration: Carbon dioxide and oxygen pass in and out of leaves by diffusion. Diffusion Summary 06/05/2017 Diffusion is when particles spread from an area of high concentration to an area of ___ concentration. The particles move along a “concentration _____” and this process takes no _____ (it’s a “passive” process”). Diffusion can be accelerated by increasing the _______ of the particles, which makes them move _______. Words – faster, low, gradient, temperature, energy Osmosis 06/05/2017 Osmosis is a “special kind of ___________”. It’s when water diffuses from a __________ area to a less concentrated area through a partially permeable _________ (i.e. one that allows water to move through but not anything else): Water Sugar solution In this example the water molecules will move from left to right (along the concentration ______) and gradually _____ the sugar solution. Plants use osmosis to take in water through their roots. Words – membrane, concentrated, dilute, diffusion, gradient Potato cells 06/05/2017 Strong sugar solution Medium sugar solution Weak sugar solution Active Transport 06/05/2017 In diffusion substances moved along a concentration gradient. In active transport, substances move against this gradient: Outside cell Inside cell Cell membrane This process takes ______ and this comes from ___________. It enables cells to take in substances even though there are in very small __________. Root hair cells take in ______ using active transport. Words – concentration, energy, respiration, nutrients 06/05/2017 Diffusion and Active Transport in plants Mineral More concentrated Carbon dioxide diffuses into the leaf through holes in the bottom surface. Less concentrated …while plant nutrients are taken in by root hair cells using active transport. Encouraging Photosynthesis 06/05/2017 Using knowledge of limiting factors, explain how plant growth is encouraged in a greenhouse: Limiting Photosynthesis What factors could limit the rate of photosynthesis? 1. Temperature – the best temperature is about 300C – anything above 400C will slow photosynthesis right down 2. CO2 – if there is more carbon dioxide photosynthesis will happen quicker 3. Light – if there is more light photosynthesis happens faster 06/05/2017 06/05/2017 Drawing graphs of these factors 1. Temperature Photosynthesis is controlled by enzymes – these are destroyed at temperatures above 400C 2. Carbon dioxide Photosynthesis increases at first but is then limited by a lack of increase in temp or light 3. Light Photosynthesis increases at first but is then limited by a lack of increase in temp or CO2 Fieldwork techniques Using quadrats 06/05/2017 Recording light levels Fieldwork techniques also involve using a key to identify plants. B4.3 How do living organisms obtain energy? 06/05/2017 06/05/2017 Uses for energy from respiration Animals and plants have many uses for the energy they generate from respiration: 1) To perform the life processes, such as moving, _____ etc 2) To build up body _______ 3) To maintain a constant body ___________ (warm-blooded mammals only) 4) To build up sugars, ________ and other nutrients in plants 5) Active __________ Words – nitrates, tissue, proteins, transport, growing Synthesis 06/05/2017 “Synthesis” means “making large molecules out of small ones”. Two examples: 1) Glucose (sugar) can be used to make long chains of insoluble starch… Glucose molecules Starch molecule 2) Glucose can be combined with nitrates to make proteins (for growth)… Glucose molecules Proteins Respiration Introduction I enjoy taking samples using quadrats. In order to do this, I need energy. Where does this energy come from? Our energy comes from a process called respiration, which basically involves turning food and oxygen into energy and this reaction is controlled by enzymes. 06/05/2017 (Aerobic) Respiration 06/05/2017 All living organisms have to move, _____, reproduce etc. Each of these life processes needs ENERGY. ___________ is the process our bodies use to produce this energy: Glucose + oxygen water + carbon dioxide + ENERGY The glucose we need comes from ______ and the oxygen from _________. Water and carbon dioxide are breathed out. The MAIN product of this equation is _________. Respiration happens in _________ in cells. Words – breathing, energy, grow, respiration, food, mitochondria Muscles and exercise 06/05/2017 When we exercise our muscles are supplied with more oxygen and glucose, increasing the rate of respiration. Muscles store glucose as glycogen which can then be converted back into glucose during exercise. Anaerobic respiration 06/05/2017 Unlike aerobic respiration, anaerobic respiration is when energy is provided WITHOUT needing _________: Glucose lactic acid + a bit of energy This happens when the body can’t provide oxygen quick enough for __________ respiration to take place. Anaerobic respiration produces energy much _______ than aerobic respiration but only produces 1/20th as much. Anaerobic respiration can also take place in other low-oxygen conditions, such as plant roots in _________ soil or bacteria in ________ wounds. Words – oxygen, aerobic, quicker, puncture, waterlogged Making Ethanol Ethanol is an important chemical. Many countries are increasing the amount of ethanol put into their petrol supplies: 06/05/2017 Ford Escape E85 – runs on 85% ethanol Ethanol is another product of anaerobic respiration in plant cells and some micro organisms: Sugar ethanol + carbon dioxide + energy Bacteria 06/05/2017 Consider a bacteria cell in more detail: Bacteria – containing cytoplasm and a membrane surrounded by a cell wall. The genes are NOT in a distinct nucleus. The cell contains a number of features, including: 1) Chromosomal DNA, containing the genetic info of the cell 2) Plasmid DNA, containing extra information such as defence mechanisms 3) Flagella, which helps the cell move The Structure of Bacteria 06/05/2017 Bacteria also have plasmids (circular strands of DNA) that can be copied and move between different bacteria. This means that resistance to antibiotics can be passed on without the need for reproduction. Respiration in Cells 06/05/2017 Notice that plant and animal cells (and bacteria) have many features that help respiration: 1) Cytoplasm where enzymes are made 2) Nucleus – carries genetic info for making enzymes 3) Cell Membrane – controls what comes in and out 4) Mitochondria – contain enzymes for respiration reactions In bacteria cells, this job is done by circular DNA Using Anaerobic Respiration 06/05/2017 Anaerobic respiration in micro organisms is used to make fuels through: 1) Manure or other waste that can be used to release methane (biogas) 2) Corn or sugar cane that can be broken down in a fermenter to produce alcohols like bio-ethanol. Anaerobic respiration is also used in fermentation to make bread and alcohol.